Saturday, March 12, 2022

Theropod Database Update March 2022 with SVP 2021 thoughts

And after a few months we're back.  This update incorporates taxa named since last time and also incorporates many of the theropod abstracts from SVP 2021.

Two new ceratosaurs were added, Guemesia and Berthasaura.  The latter is interesting in just how similar to tetanurines, and coelurosaurs and ornithomimosaurs/oviraptorosaurs in particular, the supposed noasaurid is.  Besides the obvious dentary similarities to e.g. Microvenator and highly pneumatic lacrimal, the typical ceratosaurian cervical postzygodiapophyseal lamina is reduced, the brevis fossa is reduced, and like Elaphrosaurus the femoral medial epicondyle is reduced and the fibular crest is separate from the proximal tibial condyles.  The authors recover it as the most basal noasaurid, but this seems unlikely given the Aptian-Albian age.

Among basal tetanurines, Iberospinus and "Maip" were added, each formerly in the Database as a questionable referred specimen of Suchosaurus? girardi and Megaraptoridae indet..  Dynamoterror was updated based on Yun's paper and the SVP abstract on the new specimen.  I've incorporated Paul et al.'s new Tyrannosaurus species as synonyms, but haven't gone into any detail examining the issue yet.

Left ilium of Ornitholestes hermanni holotype AMNH 619 showing plesiomorphic characters not present in pennaraptorans- highly convex supracetabular crest and deep brevis fossa (courtesy of the AMNH).

Ornitholestes
was famously recovered as an oviraptorosaur by Chapelle et al. (2021), but while their CT scanning is amazing and I can't wait for the resulting paper, I'm skeptical of that phylogenetic placement.  For one, some of their proposed synapomorphies are slightly closer to the oviraptorosaurian condition than neutral, but defining the state this loosely would result in other taxa also exhibiting the condition.  The supposedly pendant paroccipital processes for instance are slightly downturned, but not nearly as much as oviraptorosaurs' and e.g. Allosaurus has a more extreme condition.  They don't count as either short/deep or downturned using standard TWiG scoring or the Lori matrix.  The other issue is that the postcranium is so plesiomorphic that basically all pennaraptoran characters become convergences between oviraptorosaurs and paravians, which might be true, but does keep an oviraptorosaurian Ornitholestes at 18 steps longer than the shortest trees in the Lori matrix even with the new data from CT scans.  However, that data did lead to Ornitholestes moving crownward to be sister to Maniraptoriformes instead of the most basal maniraptoromorph.

"Fukuivenator" just got a huge redescription (Hattori et al., 2021), with excellent CT scans in every view.  They corrected most of what the original description got wrong (which was even more than I thought), and surprise(!) the weirdly large premaxilla WAS the other maxilla all along.  Note while they agreed with my reinterpretation of pedal phalangeal assignments, their materials list incorrectly says supposed IV-2 is actually III-2 and supposed III-1 is actually II-2, which besides just being wrong anatomically and contradicting their own figures would leave us with an extra III-2 and no III-1.  They list three "Withdrawn elements: left pterygoid; posterior caudal vertebra; left ischium" without comment, but Hattori (pers. comm. 3-4-2022) indicates the pterygoid and ischium cannot be identified in the existing materials and that the caudal is theropodan but not part of the holotypic block.  The Lori paper recovered "Fukuivenator" as the most basal alvarezsauroid but found it could be a therizinosaur with just two steps.  Hattori et al. actually recovered the latter topology, but scoring the new data in the Lori matrix leaves it sister to Ornitholestes just outside Maniraptoriformes instead.

Nqwebasaurus had new cranial material described by Radermacher et al. (2021), but they still found it in basal Ornithomimosauria using Choiniere's TWiG matrix.  Adding the new data to the Lori analysis resolved it as sister to the alvarezsauroid-therizinosaur clade, but details on the prootic and other elements in the eventual description could change things.  Pelecanimimus' postcrania were finally described by Cuesta et al. (2022), and incorporating this data moved it to Ornithomimosauria as in the consensus.  But it moves back to Alvarezsauroidea in only five steps (which moves Nqwebasaurus back there too), so it's more important than ever to get the skull (and braincase in particular) described.

Khulsanurus is a recently described alvarezsauroid (Averianov and Lopatin, 2021), but the element described as a distal pubis seems too small to be this bone, and differs from theropod pubes in the posteromedial flange and anteroposteriorly deep apron.  Considering its size and shape, this is more likely to be a proximal dorsal rib. Another new taxon is the parvicursorine Ondogurvel alifanovi described by Averianov and Loptatin (2022).  They reported it differs from Parvicursor "by the dorsally arcuate supraacetabular crest of the ilium, by the tibia less curved labially in transverse plane, by less expanded proximal part of the fibula, and by a relatively shorter pedal phalanx II-1."  While these differences are real, the femur was said to be "almost identical with the femur in Parvicursor" and the two emerge as sister taxa if entered into the Lori matrix.  As they are from the same formation and Parvicursor is a juvenile with a tibia 62% of the size of Ondogurvel, it is hypothesized here that the taxa are synonymous and the shorter pedal phalanx and fused metatarsus are ontogenetic differences while the others could be individual variation (tibial curvature is known to vary in Microraptor, for instance).  Averianov and Lopatin added Ondogurvel to a TWiG analysis and used implied weighting to recover it sister to Albinykus, but in their earlier Parvicursor redescription noted this was done because equal weighting led to large polytomies in Parvicursorinae.  Thus it does not strongly argue against synonymy with Parvicursor.  More material of the Bissekty alvarezsaurid were just described by Averianov and Sues (2022 online), which they name Dzharaonyx.  As with other Bissekty taxa, remains are isolated so may represent more than one taxon.  In this case, each referred ulna differs in that "The round facet for the aponeurosis tubercle of the radius is clearly present in the mature specimen ZIN PH 2020/16 but is absent in the juvenile ZIN PH 2021/16", and manual ungual I examples differ in that "In two specimens (ZIN PH 2445/16 and 2446/16), the collateral grooves are enclosed by notches whereas they pass through ventral foramina on the third specimen (ZIN PH 2618/16)."  While these could be individual variation, they could also indicate different taxa.

Holotype of Shuvuuia deserti IGM 100/975. Courtesy of the AMNH.

Eudromaeosaurs have gotten quite a bit of recent attention, with "Vectiraptor" from England and lots of new data on Mongolian taxa.  "Airakoraptor" was officially named Kuru (Napoli et al., 2021; Ruebenstahl et al., 2021), and again I express my displeasure for giving any taxon a genus name that is already a word because it's terrible for finding mentions in the literature or online.  Just call it "Kururaptor"- that word didn't exist before, so it would be very easy to search for every reference to it.  The Kuru talk and paper also clarified what's been a confusing issue, that supposed Velociraptor ulna IGM 100/981 was called that due to a clerical error, and is actually part of partial skeleton IGM 100/3503.  Although called Velociraptor sp. by those works, I would say it falls within the range of variation of Tsaagan.  Another Mongolian eudromaeosaur issue is the new long-snouted species of Velociraptor based on IGM 100/982, which has been hinted at since Kundrat (2004) and will be finalized once Powers' (2020) thesis chapter is turned into a paper.  What might not be as obvious is that the specimen is responsible for a good portion of what we thought was described V. mongoliensis anatomy thanks to Norell and Makovicky (1999), especially the manus.  This makes description of fighting dinosaurs V. mongoliensis skeleton IGM 100/25 even more important.

The new Crato bird pes Kaririavis was described by Carvalho et al. (2021 online).  It's weird in mixing euornithine characters like a plantarily displaced third metatarsal and hypotarsus with primitive characters like no distal fusion and a low intercondylar eminence.  The authors added it to O'Connor's bird analysis and stated it emerged in a large ornithuromorph polytomy with Piscivoravis, Yanornis, Yixianornis, Songlingornis, Iteravis, Gansus, hongshanornithids, Apsaravis, Ichthyornis, hesperornithines and neognaths in a reported 15 MPTs of 1247 steps.  However their supplementary info shows "the 15 Most Parsimonious Trees (MPTs) resulted in present phylogenetic analysis", but in all of these Kaririavis is the sister taxon to Ichthyornis.  Running the matrix actually results in 1104 shorter trees of 1246 steps where Kaririavis can go anywhere in Ornithothoraces except Hesperornithes+Aves and Schizoouridae sensu Wang et al., including trees where it is an enantiornithine.  Just to make it more complicated, Carvalho et al. claim that "35 characters [were] treated as ordered" when their included NEXUS file leaves all characters unordered by default, and when those characters (identified from the Mengciusornis analysis this was taken from) are ordered, 720 MPTs of 1274 steps are found where Kaririavis is the basalmost euornithine in each one.  When added to the Lori analysis Kaririavis can equally easily fall out as an enantiornithine or a neognath, and with a single extra step can be sister to all other euornithines with a plantarily displaced third metatarsal.  But the matrix isn't great at handling isolated metatarsi, so I'm not too confidant about any specific placement and just keep it as Ornithothoraces incertae sedis for now.

Sacrum of Bambiraptor feinbergi holotype AMNH 30556 in ventral view, anterior to left. Courtesy of the AMNH.

Two new enantiornithines were named- "Brevirostruavis" and Beiguornis.  The latter's description sadly lacks a measurements table, but the photos are better quality than usual for this kind of paper.  As for "Brevirostruavis", it was presented as a short-beaked bird with long ceratobranchials, but when reconstructed the beak isn't all that short, and no data is ever given as to shorter ceratobranchial length in other Jehol enantiornithines.  This seems to be a trend with Jehol enantiornithines, where the splashy headline is a supposed weird characteristic that doesn't end up having great evidence- horned Dapingfangornis, predatory-beaked Boluochia, Cathayornis caudatus with lots of unfused caudal vertebrae, tiny Liaoxiornis, Chiappeavis with a weird large premaxilla, heterodactyl Dalingheornis. etc..  I think that once Jehol enantiornithines are examined statistically with taphonomy and ontogeny in mind (e.g the huge changes in sternal ossification and thus shape throughout growth), a large number of genera are going to be sunk.

Finally, we have the euornithines of which the new taxa are O'Connor et al.'s (2021, 2021 online) "Meemannavis" and "Brevidentavis".  The former was found in a huge polytomy by O'Connor et al. in equally weighted strict consensus trees (note the trees in their figure are majority rule and implied weighting), but sister to Archaeorhynchus in the Lori analysis, which seems plausible.  I think this recent trend (also seen in the Ondogurvel paper, Parvicursor redescription and just this week the Dzharaonyx paper) to present implied weighting trees as a solution to a big polytomy is misleading.  As the new Musivavis paper shows (Wang et al., 2022- Fig. 14), weighting can give different results from the unweighted trees we've been using for decades and different strengths of weighting can give different topologies from each other.  The alvarezsaurid papers used a k value of 3, O'Connor et al. used a k value of 12, and none of them even try to justify their choice.  Thus instead of giving defensible cladograms, we get trees generated from arbitrarily skewing the data.  In any case, "Brevidentavis" was presented at SVP at "Brachydontornis" which also made it into a few parts of the resulting paper.  Creisler (DML, 2021) revealed "Brevidentavis" is the intended final name, and the paper will presumably be fixed once it gets out of Early View and the taxa are official.

References- Norell and Makovicky, 1999. Important features of the dromaeosaurid skeleton II: Information from newly collected specimens of Velociraptor mongoliensis. American Museum Novitates. 3282, 45 pp.

Kundrat, 2004. Two morphotypes of the Velociraptor neurocranium. ICVM-7 Abstracts. Journal of Morphology. 260(3), 305.

Powers, 2020. The evolution of snout shape in eudromaeosaurians and its ecological significance. Masters thesis, University of Alberta. 437 pp.

Averianov and Lopatin, 2021 online. The second taxon of alvarezsaurid theropod dinosaurs from the Late Cretaceous Khulsan locality in Gobi Desert, Mongolia. Historical Biology. Latest Articles. DOI: 10.1080/08912963.2021.2000976

Carvalho, Agnolin, Rozadilla, Novas, Ferreira Gomes Andrade and Xavier-Neto, 2021 online. A new ornithuromorph bird from the Lower Cretaceous of South America. Journal of Vertebrate Paleontology. e1988623. DOI: 10.1080/02724634.2021.1988623

Chapelle, Norell, Ford, Hendrickx, Radermacher, Balanoff, Zanno and Choiniere, 2021. A CT-based revised description and phylogenetic analysis of the skull of the basal maniraptoran Ornitholestes hermanni Osborn 1903. The Society of Vertebrate Paleontology Virtual Meeting Conference Program, 81st Annual Meeting. 81.

Hattori, Kawabe, Imai, Shibata, Miyata, Xu and Azuma, 2021. Osteology of Fukuivenator paradoxus: A bizarre maniraptoran theropod from the Early Cretaceous of Fukui, Japan. Memoir of the Fukui Prefectural Dinosaur Museum. 20, 1-82.

Napoli, Ruebenstahl, Bhullar, Turner and Norell, 2021. A new dromaeosaurid (Dinosauria: Coelurosauria) from Khulsan, central Mongolia. American Museum Novitates. 3982, 47 pp.

O'Connor, Lamanna, Harris, Hu, Bailleul, Wang and You, 2021. First avian skulls from the Lower Cretaceous Xiagou Formation, Gansu, China. The Society of Vertebrate Paleontology Virtual Meeting Conference Program, 81st Annual Meeting. 196.

O'Connor, Stidham, Harris, Lamanna, Bailleul, Hu, Wang and You, 2021 online. Avian skulls represent a diverse ornithuromorph fauna from the Lower Cretaceous Xiagou Formation, Gansu Province, China. Journal of Systematics and Evolution. Early View. DOI: 10.1111/jse.12823

Radermacher, Fernandez, de Klerk, Chapelle and Choiniere, 2021. Synchrotron μCT scanning reveals novel cranial anatomy of the enigmatic Early Cretaceous South African coelurosaur, Nqwebasaurus thwazi. The Society of Vertebrate Paleontology Virtual Meeting Conference Program, 81st Annual Meeting. 213-214.

Ruebenstahl, Napoli, Bhullar, Turner and Norell, 2021. Two new eudromaeosaurs from Khulsan (central Mongolia) reveal modern-like faunal predatory structure amoung non-avian dinosaurs. The Society of Vertebrate Paleontology Virtual Meeting Conference Program, 81st Annual Meeting. 222-223.

Averianov and Lopatin, 2022 online. A new alvarezsaurid theropod dinosaur from the Upper Cretaceous of Gobi Desert, Mongolia. Cretaceous Research. DOI: 10.1016/j.cretres.2022.105168

Averianov and Sues, 2022 online. New material and diagnosis of a new taxon of alvarezsaurid (Dinosauria, Theropoda) from the Upper Cretaceous Bissekty Formation of Uzbekistan. Journal of Vertebrate Paleontology. Latest Articles. e2036174. DOI: 10.1080/02724634.2021.2036174

Cuesta, Vidal, Ortega, Shibata and Sanz, 2022 (online 2021). Pelecanimimus (Theropoda: Ornithomimosauria) postcranial anatomy and the evolution of the specialized manus in Ornithomimosaurs and sternum in maniraptoriforms. Zoological Journal of the Linnean Society. 194(2), 553-591.

Wang, Cau, Luo, Kundrat, Wu, Ju, Guo, Liu and Ji, 2022. A new bohaiornithid-like bird from the Lower Cretaceous of China fills a gap in enantiornithine disparity. Journal of Paleontology. FirstView. DOI: 10.1017/jpa.2022.12

Monday, November 8, 2021

Neimengornis the chimaera, "Yuanchuavis" is another Pengornis and more - October 2021 Database update

It's time for another Database update.  The most extensive thing I did this month was update all of the links, largely due to the DML Archives being down but also affecting quite a few others.

The coelophysoid Pendraig was added.  If anyone has Warrener's 1983 thesis originally featuring the material, feel free to send a copy over.  I also researched the nomen nudum Sinosaurus "shawanensis" that was previously represented by one DML post by Olshevsky in 2002, based on my hard copy of The Jurassic System of China-

Olshevsky (DML, 2002) reported that within an incomplete set of pages he had, "On p. 9 and p. 17 the paper notes from the Lufeng Formation the species Sinosaurus shawanensis (Young) among a number of well-known dinosaur names."  He listed the reference as "Stratigraphy of China, Jurassic System, Summary, Chinese Academy of Geological Sciences, May 1979." and attributed the name to Anonymous, as there was no indication of the author in the pages he possessed.  While such a publication has never surfaced, an identical situation is present in Cheng (1985), a section of "The Jurassic System of China", volume 11 in the Stratigraphy of China series.  Perhaps Olshevsky's paper was a summary of this series printed prior to the series itself, which began in 1982.  In any case, Cheng lists "Sinosaurus shawanensis (Young)" alongside other taxa from his layer 5 of the Dark Red Beds of the Lufeng Formation (equivalent to layer 6 of Luo and Wu, 1994).  Notably this is the only species with the author listed in parentheses, which would normally indicate a species named shawanensis by Young was transferred to Sinosaurus by someone else, but while Young did name Sinosaurus triassicus neither he nor anyone else named a vertebrate species shawanensis (the only animals with that species name before 1985 are brachiopod Cryptospirifer shawanensis Jing et al., 1974 and small shelly fossil Phyllochites shawanensis Duan, 1983, neither from the Lufeng Formation).  Young (1951) did refer one tooth from Shawan to Sinosaurus (IVPP V279), but this was to S. triassicus and was from the Dull Purplish Beds, so doesn't match stratigraphically with Cheng's taxon.  As the holotype and most paratypes of S. triassicus are from the Dark Red Beds, I think Olshevsky was correct when he noted "Perhaps it is significant that Sinosaurus triassicus is not listed, which might mean that  Sinosaurus shawanensis is a synonym", as indeed S. triassicus is not listed by Cheng either.  Thus "shawanensis" is near certainly a typo for triassicus, but is still listed here as this can probably not be proven more than thirty years after the fact with the author dead. 
Note Molina-Perez and Larramendi (2019) represent Sinosaurus "shawanensis" with isolated dorsal vertebra IVPP V31, which was referred to Sinosaurus triassicus by Young (1948).  Yet its size and morphology are similar to mid dorsals of sauropodomorph skeleton IVPP V100, also referred to S. triassicus by Young (1951) in an example of that era's habit of combining sauropodomorph postcrania with jaws and teeth of carnivorous archosaurs.  Contra Molina-Perez and Larramendi, it was not "More recent than Sinosaurus triassicus", being from the Dark Red Beds as well, and has no connection to the name "shawanensis."

Speaking of Molina-Perez and Larramendi's book, I updated several nomina nuda based on data published in it.  It's a pretty impressive tome with excellent illustrations, although they are often of taxa based on fragments and thus almost entirely hypothetical.  One aspect of maintaining a list of taxa is where to draw the line between nomina nuda proposed as taxa (informally or incompletely) and nicknames.  Prior to the book, I had "Weenyonyx" as a nickname, but given its presence in the book's catalogue of spinosaurids I have now provided it with its own entry.  Baryonychine spinosaurids got retooled a bit due to new Wessex taxa Ceratosuchops and Riparovenator.  As a lumper my initial hunch was that they were individual variations of Baryonyx walkeri, but Barker et al. (2021) do an impressive job detailing all of the differences and similarities between these and 'Suchomimus' (Cristatusaurus on my site).  Based on the known anatomical data I don't think we can either synonymize the Wessex taxa or sink them into Baryonyx without also doing so to the Nigerian taxon and thus all baryonychines.  Interestingly, both Wessex taxa lack premaxillary crests unlike Cristatusaurus but they differ in the other characters in which Cristatusaurus and Suchomimus resemble each other more than Baryonyx - a less rounded anterodorsal margin to their premaxillae (also in Ceratosuchops but not Riparovenator); a comparatively larger second alveolus (also in Riparovenator but not Ceratosuchops).

I also finally moved Camarillasaurus to Spinosauridae, which was discovered back in 2019.  While Samathi et al. (2021 online) correctly reported the supposed cervical MPG-KPS24 was much too small top belong to the type, they still stated the preserved centrum articular surface was posterior.  Yet as the parapophysis is adjacent, this is a concave anterior articular surface.  Also, the labeled parapophyses in Sanchez-Hernandez and Benton's (2014) figure 3B are the neural arch peduncles and the supposed pneumatic foramen is merely a fossa.  The combination of large hypapophysis, concave to flat anterior articular surface and no dorsal pleurocoels suggests a basal alvarezsauroid, Mahakala relative, troodontid or pygostylian, so it is here assigned to Maniraptora.  The supposed coracoid strongly differs from ceratosaurian or megalosauroid theropods in being anterodistally expanded as in many paravians, having a thick lip on the lateral side of the posterior edge, and having a ventrally located foramen that is most likely damage.  The element is near certainly not a coracoid, although a proper identification would benefit from figures in multiple perspectives.

Maniraptoran anterior dorsal (MPG-KPC24) referred to Camarillasaurus cirugedae by Sanchez-Hernandez and Benton (2014; after Hernandez and Benton, 2014). As noted above, B is anterior view and 'parapophysis' in B is a neural arch peduncle.

Moving to paravians, I added Papiliovenator and also scored it in the Lori matrix where it emerged sister to Zanabazar.  Forcing it to be sister to Linhevenator or Philovenator from the same formation requires four more steps each.  I hope it gets a more detailed description in the future, as there are entire portions that are not illustrated and barely or not described by Pei et al. (2021)- manus, coracoid and proximal scapula, pelvis, etc..  

Holotype of Neimengornis rectusmim (IMMNH-PV00122) (after Wang et al., 2021). Note the different sizes of elements on each side of the specimen and other characters noted below that make this a chimaera.

Neimengornis was described by Wang et al. (2021) as a new genus of jeholornithiform, but this specimen appears to be a chimaera assembled from different individuals.  The right humerus, radius and ulna are 11%, 5% and 10% longer respectively than the left; right metacarpals I and II are 20% and 15% longer while III is 8% shorter than the left; on the right manus digit II with a larger distal articulation is given a small ungual while digit III has a large ungual matched with its more slender phalanx; there is a slender phalanx in the left manus that doesn't match any of the phalanges in the right manus; the left ilium is 84% the size of the right one with a blunter postacetabular process and less projected ischial peduncle; the right femur is 10% longer than the left, the right tarsometatarsus 13% longer, and pedal phalanges are mostly different in length between pedes.  Other probable indications are the differently shaped scapulae; arrangement of carpals in the left manus with the two small ones positioned alongside metacarpal I at the bases of metacarpals II and III; left distal astragalocalcaneum smaller than the right and seemingly disarticulated from the tibia; and retrices appearing as featureless narrow dark lines extending halfway down the tail.  With that in mind, the element identification listed above is based on Wang et al.'s interpretation of the skeleton as articulated, so the phalanges in particular are likely placed incorrectly and the left ?ulna could be a radius or tibiotarsus.  The right scapula, humeri (e.g. the short deltopectoral crest of the diagnosis) and ilia seem more similar to Sapeornis, although the skull, tail and furcula are Shenzhouraptor-grade, while the sacrum has an expanded but distally unfused last rib as in Confuciusornis and the right scapulocoracoid is more like confuciusornithiforms in the apparent fusion and short coracoid.  The radii, left ulna, tarsometatarsi and pubes all seem to be avialan, although the latter plausibly had their distal end modified to be shorter and pointed.  The right pes may be Sapeornis, which also has pedal ungual I largest and is similar in proportions.  Although the robust and straight metacarpal III and small ungual II might suggest the right manus is from a confuciusornithiform, phalanx I-1 doesn't extend past metacarpal II, digit II is much smaller and phalanx III-2 is the tiny one (unlike confuciusornithiforms and the manus in Dalianraptor where III-1 is), pointing to it being an artificial articulation of elements.  Thus we have a situation much like Dalianraptor.

Snout tip of Yuanchuavis kompsosoura (IVPP V27883). Note supposed fifth premaxillary tooth is upside down as shown in medial view (right) with protruding root appearing to be the tip in lateral view (left), so is probably a dentary tooth.  Also that the first tooth is displaced posteriorly from its alveolus as shown in medial view (after Wang et al., 2021).

Wang et al. (2021) described a supposed new taxon of pengornithid- Yuanchuavis kompsosaura based on IVPP V27883, a skeleton missing pectoral girdles and forelimbs.  Regarding its validity, the premaxilla is said to have five teeth but the medial view of the right premaxilla in figure S1B shows the last tooth is upside down so that the root protrudes ventrally as if it's a crown tip in lateral view, and so is probably a dentary tooth.  Similarly, the same figure shows the edentulous tip of the bone is exaggerated by the first tooth being displaced and artificially angled posteriorly.  The actual edentulous portion is only two FABLs long, similar to Pengornis, IVPP V18632 and Parapengornis (right premaxilla; first tooth displaced and loose in left element).  The supposedly short anterior and posterior lacrimal processes are similar to Parapengornis, IVPP V18632 and Pengornis except that the posterior process of the latter is longer as interpreted by O'Connor.  The large hypapophyses on dorsals one and two are difficult to evaluate in other Pengornis as anterior dorsals are usually disarticulated and oriented at odd angles when exposed at all.  Contra the authors, the dorsoventral depth of the dorsal central fossae (e.g. D5) are similar to IVPP V18632, Parapengornis and Chiappeavis.  Finally, the short anterodorsal pygostyle processes are also present in Parapengornis and Chiappeavis (eroded in Pengornis), while the elongate anteroventral process is also present in Parapengornis, partly exposed in Pengornis and probably hidden under caudal vertebrae in Chiappeavis.  Of the variable characters noted above for Parapengornis and Chaippeavis, the pygostyle/metatarsus ratio is intermediate (66%), metatarsal I is 42% the length of metatarsal II, and anterior cervicals are elongate, again showing no pattern and no distinct separated groups of ratios.  Thus like other Jiufotang pengornithids, Yuanchuavis is synonymized with Pengornis here.

Tail comparison of Pengornis specimens, left from Wang et al. (2021), right scaled to dorsal exposure of pygostyle length from Wang et al. (2021; top) and O'Connor et al. (2016; bottom).  Note the difference between the retrical arrangement and lengths is not nearly as great as Wang et al.'s figure would suggest, with the long central pair being known to be dimorphic in enantiornithines and confuciusornithiforms.

Finally, "Yuornis" was added without any controversy.  Interestingly, it was originally reported in an SVP abstract back in 2011 (Lu et al., 2011).  Speaking of SVP, I previously said I would comment on it in this entry, but I think it would be more useful next month.

References- Young, 1948. On two new saurischians from Lufeng, Yunnan. Bulletin of the Geological Society of China. 28, 75-90.

Young, 1951. The Lufeng saurischian fauna in China. Palaeontologica Sinica. C(13), 1-96.

Cheng, 1985. The Lufeng-Dafang Subregion. In Wang, Cheng and Wang (eds.). The Jurassic System of China. Stratigraphy of China. 11, 185-189.

Olshevsky, DML 2002. https://web.archive.org/web/20181215172409/http://dml.cmnh.org/2002Apr/msg00630.html

Lu, Xu, Zhang, Jia and Chang, 2011. A new gobipterygid bird from the Late Cretaceous Central China and its biogeographic implications. Journal of Vertebrate Paleontology. Program and Abstracts 2011, 147.

Sanchez-Hernandez and Benton, 2014 (online 2012). Filling the ceratosaur gap: A new ceratosaurian theropod from the Early Cretaceous of Spain. Acta Palaeontologica Polonica. 59(3), 581-600.

O'Connor, Wang, Zheng, Hu, Zhang and Zhou, 2016 (online 2015). An enantiornithine with a fan-shaped tail, and the evolution of the rectricial complex in early birds. Current Biology. 26(1), 114-119.

Molina-Perez and Larramendi, 2019. Dinosaur Facts and Figures: The Theropods and Other Dinosauriformes. Princeton University Press. 288 pp.

Barker, Hone, Naish, Cau, Lockwood, Foster, Clarkin, Schneider and Gostling, 2021. New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European origins of Spinosauridae. Scientific Reports. 11:19340.

Pei, Qin, Wen, Zhao, Wang, Liu, Guo, Liu, Ye, Wang, Yin, Dai and Xu, 2021 online. A new troodontid from the Upper Cretaceous Gobi basin of Inner Mongolia, China. Cretaceous Research. Journal Pre-proof. DOI: 10.1016/j.cretres.2021.105052 

Samathi, Sander and Chanthasit, 2021 online. A spinosaurid from Thailand (Sao Khua Formation, Early Cretaceous) and a reassessment of Camarillasaurus cirugedae from the Early Cretaceous of Spain. Historical Biology. Latest Articles. DOI: 10.1080/08912963.2021.1874372

Wang, Wang, Guo, Kang, Ma and Ju, 2021. A new jeholornithiform identified from the Early Cretaceous Jiufotang Formation in western Liaoning. Geological Bulletin of China. 40(9), 1419-1427. 

Wang, O'Connor, Zhao, Pan, Zheng, Wang and Zhou, 2021. An Early Cretaceous enantiornithine bird with a pintail. Current Biology. 31, 1-8.

Thursday, October 21, 2021

Identity of the mysterious "Luckyraptor" plus other new birds

Last year I noticed an entry for "Luckyraptor [Anonymous] 2007 [nomen nudum]" on Olshevsky's Dinosaur Genera List, but could not find a source for the name and George didn't remember either.  Turns out my Facebook contact Shahen remembered that it was an old DML post by Harris.  He only says "_Luckyraptor eastensis_ (it doesn't say anything about gen. or sp. nov., but I ain't heard of it anywhere else and assume it's new here!)" so I went to the source and requested a scan of the entry (Zhang, 2007).  Each taxon in Zhang's book gets a fossil photo, often bad restoration, Chinese description and notably poor English translation of said description.

As you can see, "Luckyraptor eastensis" is based on the Jixiangornis orientalis holotype, and indeed the latter's name translates to auspicious bird from the East.  So this was just a translation error that I would hesitate to even call a nomen nudum except the -raptor- versus -ornis difference is genuine and the popularity of Olshevsky's list has led to it to be listed across the internet.

 

Harris mentioned three other theropod nomina nuda in Zhang's book, one of which is Sinornithosaurus "zhaoi".  Turns out that's based on QM V1002 that was later briefly described as a Microraptor gui specimen by Xing et al. (2013).  I translate Zhang's Chinese text as-

"Sinornithosaurus zhaoi (New Species)

Theropod dinosaurs with more developed feathers. The skull is of moderate height, the neck is not very long, and the front jaw and beak are short. The teeth are not as sharp as Sinornithosaurus millenii, but they are thick and not degenerated. The forelimbs are correspondingly longer. The hind limbs are longer than the forelimbs, with three curved claws, and the body is feathered. The tail is very stiff and powerful. It is 45 cm long, three times the length of the dorsal vertebrae, and has a slender shaft. It is a type of theropod that feeds on small mammals. The species name is dedicated to the Chinese dinosaurologist Mr. Zhao Xijin.

Place of Origin: Beipiao, Liaoning

Age: Late Jurassic to Early Cretaceous"

However, its humerofemoral ratio (~86%) is actually shorter than the S. millenii holotype (~91%) and Microraptor teeth are typically less elongate than Sinornithosaurus'.  The slender ischium, short tibia, elongate pedal phalanx IV-4 and long leg remiges all support assigning QM V1002 to Microraptor instead of Sinornithosaurus and it is here considered a junior synonym of M. zhaoianus.  "zhaoi" and the following two taxa are nomina nuda as there is no "explicit fixation of a holotype, or syntypes" (ICZN Article 16.4.1).

Next we have "Jinzhouornis" "delicates".  My translation is-

"Jinzhouornis delicates (New Species)

The primitive bird whose individual is smaller than the petite Liaoxiornis, belongs to the Enantiornithes group. The head is short and round, the skull is relatively developed, and the jaw has teeth. The outer body is feathered, and the forelimbs have become wings. There are 3 curved finger claws, which are relatively developed, the sternal keel is prominent, the caudal vertebra have fused, and the tail is short. There are two Lycoptera fossils on the slab of Jinzhouornis delicates. There is a plant fossil in the middle. This fossil is the smallest bird fossil discovered in the Late Jurassic-Early Cretaceous Yixian Formation of western Liaoning, China, and it remains to be studied.

Place of Origin: Yixian County, Liaoning

Age: Early Cretaceous"

The generic assignment is odd because Jinzhouornis is a confuciusornithid (and indeed, a junior synonym of Confuciusornis), but this is stated to be an enantiornithine.  That identification seems to be correct, given the short fused premaxillae preserved left of the main skull, coracoid and humeral shape, tiny diamond-shaped sternum, and manus with short digit I and reduced ungual and seemingly long metacarpal III projecting past II.  In addition to the sternal anatomy, the poorly ossified ends of elements and stated small size strongly suggests a young age.  The description seems inaccurate in that the round head is probably due to beak elements overlapping the posterior cranium (contra the restoration), the manual unguals are not well developed or necessarily three in number, and the sternum shows no sign of a keel.  The other details are congruent with a juvenile enantiornithine, and this specimen is likely indeterminate as are most other juvenile enants (e.g. Liaoxiornis, Dalingheornis, GMV-2158 and 2159).

Finally, there's "Smallornis liaoningica", whose entry I translate as-

"Smallornis liaoningica (new species)  

The parietal bones are well developed, the posterior edge of the orbit is concave, the eye holes are large, the beak is long, and the fingers and claws are particularly curved. The forelimbs are covered with very delicate feathers, and the down feathers on the head are more beautifully decorated. Smallornis liaoningica is a very small arboreal bird.  

Place of Origin: Yixian County, Liaoning  

Age: Early Cretaceous"

 

This is most of a bird skeleton, only missing one of the hindlimbs below the knee.  Unfortunately the available image quality means that it can't be determined whether this is an enantiornithine or euornithine, although the coracoid structure shows it is ornithothoracine.  Obviously none of the listed characters are diagnostic past Pennaraptora or so, but I expect enough is preserved to make it valid compared to named Jehol taxa.  Until we have a better scan, I'd say leave it as Ornithuromorpha incertae sedis.

If anyone has further information like specimen numbers, provenance or higher quality scans for "delicates" or "Smallornis", feel free to share.

References- Zhang, 2007. The Fossils of China. China University of Geosciences Press. 502 pp.

Xing, Persons, Bell, Xu, Zhang, Miyashita, Wang and Currie, 2013. Piscivory in the feathered dinosaur Microraptor. Evolution. 67(8), 2441-2445.

Monday, September 27, 2021

"Megalosaurus" cloacinus and more - September 2021 Database Update

Hi everyone.  I realize it's been ten months since the last post, and that's because I've been prioritizing updating the Database over writing blogs.  As a compromise of sorts and to not force people to constantly check the Database updates page, I decided to try out posting when I update including features that could have made it into their own blog post.

One thing I've been doing is working my way through Skawiński et al.'s (2017) paper on Polish Triassic dinosaur reports, which in addition to unnamed fragments, also led to the creation of entries for two supposed Megalosaurus species.  silesiacus is a generic carnivorous archosauriform tooth too early to be dinosaurian, while cloacinus has been used for basically every carnivorous archosaur tooth from Rhaetian beds of Germany.  The interesting thing about the latter is that workers apparently forgot that it was based on lost teeth described by Quenstedt, not the SMNS tooth figured 47 years later by Huene.

"Zanclodon" silesiacus Jaekel, 1910
= Megalosaurus silesiacus (Jaekel, 1910) Kuhn, 1965
Early Anisian, Middle Triassic
Lower Gogolin Formation, Lower Muschelkalk, Poland
Holotype
- (University of Griefswalden/Göttinger coll.; lost?) tooth (24x12x5 mm)
Referred- ?(Geological Museum of the Polish Geological Institute-National Research Institute coll.) tooth (Skawiński, Ziegler, Czepiński, Szermański, Tałanda, Surmik and Niedźwiedzki, 2017)
?(Silesian University of Technology, Faculty of Mining and Geology coll.) tooth (37 mm) (Surmik and Brachaniec, 2013)
Comments
- Jaekel (1910) noted (translated) "a dinosaur tooth from the lower shell limestone of Upper Silesia, which would probably be the oldest known dinosaur tooth to date. It comes from the Chorzov strata of the lower shell limestone of Gogolin, Upper Silesia, and came to me through the kindness of engineer Fedder in Opole. The crown shown is 24 mm high, 12 mm wide and 5 mm thick, so it is quite strongly compressed and slightly curved backwards. Its edge is extremely finely serrated (Fig. 16 A). I call the form, which for the time being cannot be specified generically, Zanclodon silesiacus. The only difference between [phytosaur Mesorhinosuchus] and this tooth form lies in the fact that the former is somewhat thicker, somewhat less bent back, and that no notch can be detected on the edge."  He referred it to Megalosauridae, and Kuhn (1965) later referred it to the genus Megalosaurus.  Carrano et al. (2012) correctly noted "could be considered as Theropoda indet., but we cannot rule out the possibility that it represents a 'rauisuchian' archosaur."  Surmik and Brachaniec (2013) describe a tooth from Gogolin Quarry in which "a poor state of preservation makes it impossible to identification of the presence of edge serration, however it still shows a slightly curvature and specific both sides flattening" and identify it as seemingly archosaurian.  Skawiński et al. (2017) listed this and another tooth labeled as Megalosaurus silesiacus as other material of Zanclodon silesiacus.  The latter tooth is stated to be serrated mesially and distally with a density of 12 per 5 mm.  They describe the holotype tooth as "Probably lost" and "lost", and place all three teeth as Archosauromorpha indet..  They are more specifically referred to the Teyujagua plus archosauriform clade here given the recurvature and small serrations, as authors from Kuhn onward have noted plesiomorphic theropod teeth are difficult to distinguish from several clades of archosauriforms (e.g. erythrosuchids, euparkeriids) known from the Anisian.  The age is far too early for Megalosaurus or another neotheropod, and the presence of serrations is unlike Zanclodon, so neither genus is appropriate.  It should also be noted the three Gogolin teeth differ in shape with the Silesian University specimen less recurved and less tapered than the other two, while the Polish Geological Institute specimen is shorter than the holotype and less concave distally.  This could be positional variation, but given the lack of proposed synapomorphies could easily represent multiple taxa.
References
- Jaekel, 1910. Ueber einen neuen Belodonten aus dem Buntsandstein von Bernburg. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin. 5, 197-229.
Kuhn, 1965. Fossilium Catalogus 1: Animalia. Pars 109: Saurischia. Ysel Press. 94 pp.
Carrano, Benson and Sampson, 2012. The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology. 10(2), 211-300.
Surmik and Brachaniec, 2013. The large superpredators' teeth from Middle Triassic of Poland. Contemporary Trends in Geoscience. 2, 91-94.
Skawiński, Ziegler, Czepiński, Szermański, Tałanda, Surmik and Niedźwiedzki, 2017 (online 2016). A re-evaluation of the historical 'dinosaur' remains from the Middle-Upper Triassic of Poland. Historical Biology. 29(4), 442-472.

 

Holotype tooth of "Zanclodon" silesiacus (University of Griefswalden/Göttinger coll.; lost?) in labial (A), basal section (B) and more apical section (C) (after Jaekel, 1910).

"Megalosaurus" cloacinus Quenstedt, 1858
= Plateosaurus cloacinus (Quenstedt, 1858) Huene, 1905
= Gresslyosaurus cloacinus (Quenstedt, 1858) Huene, 1932
= Pachysaurus cloacinus (Quenstedt, 1858) Huene, 1932
Rhaetian, Late Triassic
Exter Formation, Germany
Syntypes
- (lost) two teeth
Referred- ?(GPIT and SMNS coll.) many teeth (Huene, 1905)
?(SMNS 52457) tooth (~25x11x? mm) (Huene, 1905)
?(SMNS coll.) teeth (Roemer, 1870)
? seven teeth (Miller Endlich, 1870)
Norian-Rhaetian?, Late Triassic
'Lisów Breccia', Poland
?(University of Wroclaw coll.; lost) two teeth (Roemer, 1870)
Early Hettangian, Early Jurassic
Calcaire de Valognes, Manche, France
?(University of Caen coll.; destroyed) tooth (Rioult, 1978)
Comments- Quenstedt (1858) originally described (translated) "barb-shaped teeth, which are sharp and finely serrated on the concave side, but rounded and smooth on the convex side" with a large mesioapically placed wear facet that makes that edge look straight in side view.  He also figures a smaller tooth which has mesial serrations apically that transition to a rounded edge basally.  These teeth do not share any obvious synapomorphies and differ in elongation (height/FABL ~300% vs. 138%) and transverse thickness (42% vs. 75% of FABL), so may not belong to the same taxon.  Miller Endlich (1870) figured seven teeth from the type locality, stating (translated) they "are mostly flat teeth, slightly curved on one side, with fine serrations on the sharp inner edge. The convex side, the back, does not seem to be serrated, but it is not certain."  The figured teeth show a wide range of variation, with figure 13 in particular being stout and unrecurved with large serrations, similar to the Lucianosaurus paratype and similarly referrable to Archosauromorpha incertae sedis.  The other teeth have small serrations, with 14 and 18 being straight and 15-17 and 19 being recurved, with 14, 18 and 15 being progressively more transversely compressed.  As with the syntypes, these exhibit variation which could be positional or interspecific, and share no obvious characters that connect them to each other or the syntypes.  Roemer (1870) wrote (translated) "In the Stuttgart Museum I saw teeth from the bone breccia of Bebenhausen near Tubingen, which show the same fine serration of the side edges as the teeth described by Quenstedt, but are not curved in a sickle shape, but are straight. It is very likely that these latter teeth belong to the same dinosaur as the crooked teeth. With these straight teeth from Bebenhausen, the tooth shown in FIGS. 4 and 5 from the Lisów Breccia from Lubsza near Woźniki completely coincides. The double-edged tooth, which is very delicately and regularly notched at the edges, shows a more strongly curved (outer) and a less curved (inner) surface, both of which are smooth except for a very fine, irregular wrinkle. There is also a much smaller tooth of the same type from the same location."  The straight Bebenhausen teeth sound similar to Miller Endlich's figures 14 and 18, although the illustrated straight tooth from Lubsza differs from these in having an increased amount of mesiodistal expansion basally.  The Lubsza tooth also has this marked basal expansion labiolingually, and both types of root expansion are atypical of dinosaurs, suggesting this is some other type of vertebrate.  Dzik and Sulej (2007) suggested it "may have belonged to a phytosaur" without evidence but Skawiński et al. (2017) stated "phytosaur fossils have not been found in the upper Keuper strata in Silesia" and instead placed it in Archosauromorpha indet..  While this could merely mean phytosaurs were rare in that strata, phytosaur teeth don't seem to have expanded roots either (e.g. Nicrosaurus), and it could even be a fish tooth which often have these types of root expansion.  Huene (1905) listed the species as "Plateosaurus" cloacinus within Theropoda, stating it includes Rhaetian dentary "Zanclodon cambrensis".  In 1908 he places it in Plateosauridae within Theropoda and states (translated) "The originals can no longer be found. The Tübingen collection still has several teeth from Bebenhausen and Schloßlesmuehle, which can be reconciled well with [Quenstedt's] fig. 12 (l. c.), but are larger. The serrations are coarse and short, the mesial carina does not extend all the way to the base."  He illustrated a tooth in figure  274 as "From the Rhaetian Bonebed of Bebenhausen near Tübingen. Tooth in nat. Size. The tip is missing. Original in the natural history cabinet in Stuttgart."  Regarding cambrensis, Huene states "The teeth have the greatest resemblance to Plateosaurus cloacinus both in the whole shape and in the serrations. Whether it is really the same or just a very similar species, of course, cannot be decided with certainty given the scanty material", which is not explicit enough to evaluate given published details.  Huene later (1932) assigns cloacinus to Teratosauridae within Carnosauria, listed as both Pachysaurus cloacinus (pg. 6) and Gresslyosaurus cloacinus (pg. 72, 114).  Steel (1970) calls it Gresslyosaurus cloacinus within Plateosauridae.  Buffetaut et al. (1991) mentions "A tooth referred to Megalosaurus cloacinus Quenstedt, from the Lower Hettangian of the Calcaire de Valognes at Valognes (Manche), [which] has been mentioned by Rioult (1978a) as having been destroyed by an air raid on the University of Caen in 1944."  Without additional details, it can only be said that the timing suggests a neotheropod.  Carrano et al. (2012) incorrectly claimed SMNS 52457, apparently the tooth in Huene's (1908) figure 274, is "the holotype and only specimen" of cloacinus, when Huene stated it was only one of "Many teeth ... in the stone quarries of the Schoenbuch (e.g. Bebenhausen, Schloesslesmuehle), Wuerttemberg; in the university collection in Tubingen and in the natural history cabinet in Stuttgart", and that Quenstedt's originals were lost.  SMNS 52457 could be made into a neotype, but this must be done explicitly (ICZN Article 75.3) and so has not been accomplished yet.  Carrano et al. say the specimen "is a serrated, recurved tooth of the form typical for theropods. It is mesiodistally slender but does not show any diagnostic features and is therefore Theropoda indet", but other taxa with similar teeth lived in the Rhaetian (e.g. crocodylomorphs, Daemonosaurus), so is here placed in Archosauriformes indet..  Note Huene (1905, 1908) used "Plateosaurus" as a placeholder genus because until 1911 Plateosaurus was thought to have carnivorous teeth, and used "Pachysaurus" and "Gressylosaurus" in 1932 because until the 1980s more robust 'prosauropod' postcrania were still associated with carnivorous cranial elements, while Huene viewed megalosaurids as Jurassic carnosaurs.  Our modern consensus suggests a Rhaetian theropod is more likely to be coelophysoid or dilophosaur-grade than megalosaurian, but the genus is still used here as a placeholder as Megalosaurus teeth are more similar to cloacinus' syntypes and SMNS 52457 than prosauropod teeth.
References- Quenstedt, 1858. Der Jura. H. Laupp'schen. 842 pp.
Miller Endlich, 1870. Das Bonebed Württembergs. Druck Von Ludwig Friedrich Fues. 30 pp.
Roemer, 1870. Geologie von Oberschlesien. Robert Nischkowsky. 587 pp.
Huene, 1905. Uber die Trias-Dinosaurier Europas. Zeitschrift der Deutschen Geologischen Gesellschaft. 57, 345-349.
Huene, 1908. Die Dinosaurier der Europäischen Triasformation mit berücksichtigung der Ausseuropäischen vorkommnisse. Geologische und Palaeontologische Abhandlungen. Supplement 1(1), 1-419.
Huene, 1932. Die fossile Reptil-Ordnung Saurischia, ihre entwicklung und geschichte. Monographien zur Geologia und Palaeontologie. 1, 1-362.
Steel, 1970. Part 14. Saurischia. Handbuch der Paläoherpetologie. Gustav Fischer Verlag. 1-87.
Rioult, 1978. Inventaire des dinosauriens mésozoïques de Normandie. Ecosystèmes continentaux mésozoiques de Normandie (Livret-guide). Université de Caen. 26-29.
Buffetaut, Cuny and le Loeuff, 1991. French dinosaurs: The best record in Europe? Modern Geology. 16, 17-42.
Dzik and Sulej, 2007. A review of the early Late Triassic Krasiejów biota from Silesia, Poland. Palaeontologia Polonica. 64, 1-27.
Carrano, Benson and Sampson, 2012. The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology. 10(2), 211-300.
Skawiński, Ziegler, Czepiński, Szermański, Tałanda, Surmik and Niedźwiedzki, 2017 (online 2016). A re-evaluation of the historical 'dinosaur' remains from the Middle-Upper Triassic of Poland. Historical Biology. 29(4), 442-472.

Syntype teeth of "Megalosaurus" cloacinus (lost) in side and sectional views (after Quenstedt, 1858).

Other named specimens from the paper include the archosauromorph femur Zanclodon? "antiquus" based on a museum label, and neotheropod fibula Velocipes.  The latter was hilariously assigned to "Vertebrata, nomen dubium" by Rauhut and Hungerbuhler (2000), which is an example of a modern classification philosophy I dislike.  Nesbitt et al. (2007) is another egregious example, where a small subset of phylogenetically useful features are checked for, then a specimen is just thrown into whatever clade those features can narrow it to indet..  As opposed to then asking what differences exist between members of that clade and checking the specimen for them, like what Ezcurra and Brusatte (2011) did for Camposaurus.  I bet if someone did an in depth study, we would find differences between shuvosaurid and coelophysoid dorsals and caudals and thus be able to narrow down a lot of specimens currently sitting in Archosauria indet. for instance.

The other thing about Skawiński et al.'s Velocipes discussion that didn't fit into its Database entry is that they claim "It is worth noting that there is great variation in shape of proximal end of fibula of Coelophysis bauri in proximal view – some specimens are more rectangular and others more triangular, some bear flat medial surface, while in others it is strongly concave (compare von Huene 1915, fig. 51; Hutchinson 2002, fig. 2c; Spielmann et al. 2007a, fig. 6 H)."  But this is comparing Arroyo Seco AMNH 2745 with Padian's unnamed Petrified Forest coelophysoid (Ezcurra et al., 2021) with the Snyder Quarry coelophysoid, that are not necessarily conspecific.

Another set of specimens I've been adding/updating over the past several months are Triassic American records, with Arizona and the few bits from Utah complete, I'm currently getting through Texas.  That included Camp's material such as Spinosuchus (that is seemingly a Trilophosaurus species), and revising the Protoavis entry.  There's a lot of new detail in the latter such as the braincase being compatable with what we now know of non-averostran theropods, the skull roof matching Megalancosaurus, Paul's herrerasaurian characters no longer making sense, the coelophysoid proximal femur being robust and thus probably not juvenile, and commentary on the Kirkpatrick Quarry materials.

Protoavis texensis holotype proximal femur (TTU-P9200; top) in anterior view (after Chatterjee, 1991) compared to "Megapnosaurus" kayentakatae holotype (MNA.V.2623; bottom) (after Rowe, 1989). Note the muscle scars in the former typical of robust coelophysoids.

Speaking of coelophysoids, I finally gave up the battle for Bakker's original Neotheropoda concept and changed everything to the current consensus usages of Neotheropoda and Averostra.  Similarly, dilophosaurs are now closer to averostrans, but I note that this isn't as well supported as the consensus would have you believe, with Cau's matrix in the Saltriovenator paper changing to coelophysoid Dilophosaurus in only two steps and Nesbitt's matrix as altered by Ezcurra (and partially corrected by myself) needing only three steps.  However, Wang et al. (2016) needs a whopping eighteen more steps to place Dilophosaurus in Coelophysoidea, so that would be interesting to compare to Tykoski's (2005) thesis that took twenty additional steps to place Dilophosaurus closer to averostrans.  As part of the coelophysoid revision, Sarcosaurus was updated after Ezcurra et al. (2021).

New abelisaurid Kurupi was added.  An upcoming goal is to change Abelisauridae to the stem (away from Noasaurus and Ceratosaurus), and probably move Noasauridae outside Neoceratosauria.

New tetanurines are Ulughbegsaurus and "Cryptotyrannus", which had previously been referenced as both an ornithomimosaur and tyrannosauroid in the site.  I started to sort out and correct the eastern United States records for those groups now that I have the references instead of relying on Ford's list like I did for much of the original Tyrannosauroidea page, but there's more work to be done in that department.

I also added new unenlagiines Ypupiara and "Lopasaurus".  I found a quote in Bertini et al. (1993) seemingly referring to the latter in part- "tibia, a femur and metatarsals (all in the DNPM, Rio de Jineiro) which Price believed included at least two new genera and families [of coelurosaurs]." Intriguingly they also mention "a partial toothless dentary (with alveoli but lacking teeth) of a coelurosaur from Loc. 99" which sounds like Ypupiara, but unlike the latter is from a different locality than "Lopasaurus".

Finally, we have new birds that were added to the cladograms but not given entries yet.  Youornis is uncontroversial, but Yuanchuavis looks to just be another Pengornis but with typically dimorphic elongate retrices unlike the 'Chiappeavis' specimen.  Wasaibpanchi is a Malkani taxon that I don't think is identifiable as theropodan or as teeth from available photos, let alone as a valid taxon of enantiornithine.  But that requires going over Malkani's new 2021 paper, and the only thing I've incorporated from that so far is changing which sauropod taxa are valid and listing his new sauropod taxonomic groups and definitions.

See you in a month.

Additional References-  Rowe, 1989. A new species of the theropod dinosaur Syntarsus from the Early Jurassic Kayenta Formation of Arizona. Journal of Vertebrate Paleontology. 9(2), 125-136.

Chatterjee, 1991. Cranial anatomy and relationships of a new Triassic bird from Texas. Philosophical Transactions of the Royal Society of London Series B. 332(1265), 277-342.

Bertini, Marshall, Gayet and Brito, 1993. Vertebrate faunas from the Adamantina and Marília formations (Upper Bauru Group, Late Cretaceous, Brazil) in their stratigraphic and paleobiogeographic context. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen. 188(1), 71-101.

Rauhut and Hungerbuhler, 2000. A review of European Triassic theropods. Gaia 15, 75-88.

Tykoski, 2005. Anatomy, ontogeny and phylogeny of coelophysoid theropods. PhD Dissertation. University of Texas at Austin. 553 pp.

Nesbitt, Irmis and Parker, 2007. A critical re-evaluation of the Late Triassic dinosaur taxa of North America. Journal of Systematic Palaeontology. 5(2), 209-243. 

Ezcurra and Brusatte, 2011. Taxonomic and phylogenetic reassessment of the early neotheropod dinosaur Camposaurus arizonensis from the Late Triassic of North America. Palaeontology. 54(4), 763-772.

Wang, Stiegler, Amiot, Wang, Du, Clark and Xu, 2016. Extreme ontogenetic changes in a ceratosaurian theropod. Current Biology. 27(1), 144-148.

Ezcurra, Marsh, Irmis and Nesbitt, 2021. A revision of coelophysoid theropod specimens from Petrified Forest National Park, Arizona (U.S.A.), reveals a new species from the Upper Triassic Chinle Formation. 34 Jornadas Argentinas de Paleontologia de Vertebrados, Libro de Resumenes. R16.

Sunday, December 6, 2020

Antarctic Ichthyornis solved

So I've been doing some major updates to the Database for what will probably be a New Years upload, including the ornithuromorph section. One rather sad entry as it currently stands is the Antarctic Ichthyornis

I? sp. (Zinsmeister, 1985)
Late Cretaceous
Seymour Island, Antarctica
Reference
- Zinsmeister, 1985. 1985 Seymour Island expedition. Antarctic Journal of U.S. 20, 41-42. 

Now with Googling I found the original paper online, which allowed only a bit of improvement-

I? sp. (Zinsmeister, 1985)
Late Maastrictian, Late Cretaceous
Lopez de Bertodano Formation, Seymour Island, Antarctica

Material- several elements
Comments
- Zinsmeister (1985) states "several small bones tentatively identified as belonging to the Cretaceous bird Ichthyornis were discovered in the upper Cretaceous Lopez de Bertodano formation." 
Reference- Zinsmeister, 1985. 1985 Seymour Island expedition. Antarctic Journal of U.S. 20, 41-42.

So I saw that Zinsmeister worked with Chatterjee in the 80s, who found the Polarornis holotype in the same place two years before that.  I emailed Chatterjee about it, who replied-

"It was misidentified in the field. These were some shark teeth."

Mystery solved!  But can we do better?  Here's an Ichthyornis tooth-

Right eleventh dentary tooth of Ichthyornis dispar (YPM 1450) (after Field et al., 2018).

And here's the array of shark teeth from the Lopez de Bertodano Formation of Seymour Island (from a January 2011 expedition).  Can we find any easily confusable matches?

Chondrichthyan teeth from the Lopez de Bertodano Formation (scale 10 mm) (after Otero et al., 2014).

I think the circled 16 and 17 are pretty decent matches for a field identification, though much larger if compared directly.  Figures 6-17 are all identified as Odontaspidae indet., which covers any morphology similar to Ichthyornis.  Add in the fact that they were by far the most abundant teeth recovered (8 samples versus 1-3 for the other taxa), and I think we have a nice solution on our hands.

I wonder how many other weird records are out there that are based on initial misidentification but stay in the literature because nobody ever publishes a correction?


References- Otero, Gutstein, Vargas, Rubilar-Rogers, Yury-Yañez, Bastías and Ramírez, 2014. New chondrichthyans from the Upper Cretaceous (Campanian-Maastrichtian) of Seymour and James Ross islands, Antarctica. Journal of Paleontology. 88(3), 411-420.

Field, Hanson, Burnham, Wilson, Super, Ehret, Ebersole and Bhullar, 2018. Complete Ichthyornis skull illuminates mosaic assembly of the avian head. Nature. 557, 96-100.

Saturday, November 28, 2020

Is Falcatakely a bird?

So this week we got the description of the new Maevarano skull Falcatakely forsterae (O'Connor et al., 2020).  It's a pseudo-toucan, with a long, tall snout formed mostly by the maxilla unlike modern birds.  O'Connor et al. recover it as an enantiornithine using Brusatte et al.'s TWiG analysis and O'Connor's bird analysis.  Our problem is that we only have the anteroventral skull preserved, so no braincase, mandible or postcrania.  And being a Maastrichtian deposit in Africa, we don't have the most detailed coelurosaur record.  Add in the fact beaks are known to evolve fast on islands (as Madagascar was even back then) and we have a potential problem on our hands.

 

Follow your nose to the exciting topic of African coelurosaur diversity.  Reconstructed holotype skull of Falcatakely forsterae (UA 10015) (after O'Connor et al., 2020).

The Lori analysis places Falcatakely in two potential positions- a therizinosaurid or an omnivoropterygid.  The former doesn't make much sense biostratigraphically, but there is a Maevarano synsacrum of the correct size (FMNH PA 741) that was claimed to share characters with Sapeornis by O'Connor and Forster (2010).  So there's a possibility.  Forcing Falcatakely to be an enantiornithine as in O'Connor et al.'s analyses requires six more steps.  Most of the discordant characters relate to the beak, but the wide laterotemporal fenestra would be odd in an enantiornithine.  While I was writing this, Andrea Cau published a post on this topic and reported that he recovered Falcatakely as a noasaurid, which would be quite the phylogenetic jump, but it only takes three more steps in the Lori matrix, so is more parsimonious than the enantiornithine option.  It falls out as an elaphrosaurine, so could relate to e.g. Afromimus.  The non-beak contradictory characters here include a lack of antorbital fossa lacrimal foramen, long posterior lacrimal process and triradiate palatine, which seem more convincing to me.  Additional evidence against these latter two positions is the absence of small ceratosaur (Masiaksaurus is twice as big) or large enantiornithine (Maevarano elements are much smaller) postcrania.  Andrea reported (translated) "It takes 6 further steps to place it in Coelurosauria, and in that case it is a basal dromaeosaurid: interesting in that regard to note that Rahonavis , known from the same Formation, has also been hypothesized to be a basal dromaeosaurid. Can we rule out that Falcatakely is the (still unknown) skull of Rahonavis? The estimated dimensions of the two animals coincide."  Forcing Falcatakely to be Rahonavis only requires one more step, which is pretty impressive.  In their (amazing) osteology, Forster et al. (2020) refer an isolated dentary "found near the Rahonavis holotype (its precise location was not recorded during excavation)" which does not match Falcatakely's upper jaw, being upcurved and extensively toothed.  But it is similar to other unenlagiines like Buitreraptor and Austroraptor.  So much as we have two synsacrum types at this size, unenlagiine-like Rahonavis and Sapeornis-like, we have two cranial types, unenlagiine-like and Falcatakely which is Sapeornis-like in the combination of reduced maxillary dentition, triradiate palatine, modified/reduced antorbital fossa, anteriorly limited naris and strong postorbital-jugal articulation.

Referred dentary of Rahonavis ostromi (FMNH PA 740) as a transparent CT reconstruction (after Forster et al., 2020).

Thus my best guess is that Falcatakely is a basal avialan belonging to the same taxon as FMNH PA 741.  But this comes with a huge chunk of salt as it is so far removed temporally and geographically from potential comparable sister taxa.  Which is actually a common problem with this part of the tree, as shown by Balaur (= Elopteryx?), Hesperonychus, Imperobator and even Rahonavis itself.  We compare these Late Cretaceous taxa to our far more complete Early Cretaceous Jehol record and say Hesperonychus is sorta like Microraptor, Falcatakely is kind of like Sapeornis and Balaur is Jeholornis-grade, but North America, Africa and Europe had their own avialan fauna for 70 million years before them that we're basically unaware of.  If the only alvarezsauroid we had was Mononykus' holotype, could we place it correctly as a basal maniraptoran?  If the only oviraptorosaur we had was Citipati's skull, would we recover that correctly as the sister taxon of Paraves?  I think that's the position we find ourselves in with Falcatakely, and that future discoveries of African small theropods will lead to new interpretations.

 

References- O'Connor and Forster, 2010. A Late Cretaceous (Maastrichtian) avifauna from the Maevarano Formation, Madagascar. Journal of Vertebrate Paleontology. 30(4), 1178-1201.

Cau, 2020 online. theropoda.blogspot.com/2020/11/falcatakely-eterodossia-e-pluralismo.html

Forster, O'Connor, Chiappe and Turner, 2020. The osteology of the Late Cretaceous paravian Rahonavis ostromi from Madagascar. Palaeontologia Electronica. 23(2):a31.

O'Connor, Turner, Groenke, Felice, Rogers, Krause and Rahantarisoa, 2020. Late Cretaceous bird from Madagascar reveals unique development of beaks. Nature. DOI: 10.1038/s41586-020-2945-x

Friday, July 24, 2020

The Arguable Identity of Paraxenisaurus

Hi everyone.  In light of Cau's recent post on the supposed new Mexican deinocheirid "Paraxenisaurus normalensis" (Serrano-Brañas et al., 2020), I figured I'd check the taxon out to see what I thought.

The first thing you might note are the quotation marks surrounding its name, as this is yet another example of authors not including an lsid or reference to ZooBank in their electronic descriptions.  ICZN Article 8.5.3. states names published electronically must "be registered in the Official Register of Zoological Nomenclature (ZooBank) (see Article 78.2.4) and contain evidence in the work itself that such registration has occurred", and the pre-print is said to be in preparation for Volume 101 of Journal of South American Earth Sciences, cited as August 2020.  Thus it gets to join the ranks of "Thanos" and "Trierarchuncus"as theropods that will eventually be validly named this year.  But at least it's not stuck in the purgatory of twelve Scientific Reports Mesozoic theropods, which will never be physically published and thus will remain invalid unless outside action is taken.

One of the big takeaways from Cau's blogpost is that "I am doubtful about the possibility of referring these elements [the paratypes] to the same species of the holotype, since there are very few superimposable elements among the three specimens. Therefore, there is a risk that Paraxenisaurus , - understood as the sum of all three specimens - is a chimera."  After reading the paper, Andrea REALLY undersold this critique.  Here are the specimen materials lists, with the overlapping elements highlighted in matching colors-

(BENC 2/2-001; proposed holotype) proximal manual phalanx II-2 or III-3, partial astragalocalcaneum, partial metatarsal II, phalanx II-1 (115 mm), proximal phalanx II-2, partial metatarsal III, proximal phalanx III-3, distal metatarsal IV, phalanx IV-1 (104 mm), phalanx IV-3 (67 mm), phalanx IV-4 (45 mm), partial pedal ungual IV
(BENC 1/2-0054) distal metacarpal I, proximal phalanx I-1, partial manual ungual I, distal metacarpal II, distal phalanx II-2
(BENC 1/2-0091) several proximal caudal central fragments (66, 75, 76 mm), proximal metacarpal II, partial metacarpal III, distal femur (155 mm trans), distal metatarsal IV
(BENC 1/2-0092) several distal caudal vertebrae (70, 71 mm)
(BENC 30/2-001) pedal ungual II, pedal ungual III


As you can see, there's only one strict overlap, with BENC 1/2-0091 sharing a distal metatarsal IV with the proposed holotype, found ~14 kilometers away.  The paper lists no proposed apomorphies or unique combination of characters for distal metatarsal IV, and indeed the description states they preserve largely non-overlapping portions-

"In the holotype, the distal articular surface is fragmented (Figures 11a1 and 11a2); but in the referred specimen (BENC ½-0091), this surface is nicely preserved and has a non-ginglymoid outline (Figures 11b1 and 11b2). The medial condyle is mostly preserved in the holotype (Figure 11a3), but in the referred specimen it is completely broken (Figure 11b3). Conversely, the lateral condyle is broken in the holotype (Figure 11a4), but is well preserved in the referred specimen (Figure 11b4). Collateral ligament fossae are well developed on both condyles and have approximately the same size and depth (Figures 11a3 and 11b4). In cross-section, the shaft of metatarsal IV near the distal end is thicker dorsoventrally than wide."

Needless to say, metatarsal IV has a shaft which is deeper than wide in all ornithomimosaurs, and the preserved ligament fossae are on opposite sides in each specimen (medial in proposed holotype, lateral in 1/2-0091).  Below is a figure comparing the two Mexican specimens with Ornithomimus velox, with 1/2-0091 flipped so that all are comparable as left elements.  I don't see anything the "Paraxenisaurus" specimens have in common that could diagnose a taxon.

Left distal metatarsal IV of (left to right) intended "Paraxenisaurus normalensis" holotype BENC 2/2-001, intended "Paraxenisaurus normalensis" paratype BENC 1/2-0091 (right element flipped), and Ornithomomus velox holotype YPM 542 in (top to bottom) dorsal, lateral, ventral and medial views ("Paraxenisaurus" after Serrano-Brañas et al., 2020; Ornithomimus after Claessens and Loewen, 2016).

While no other elements are exactly matched, referred specimen BENC 30/2-001 does include pedal unguals II and III, while the intended holotype has pedal ungual IV.  These are again from different localities, although closer this time (~2.8 km), and this time we have characters listed in the diagnosis- 

"(9) distinctively broad and ventrally curved pedal unguals that angled downward with respect to the proximal articular surface and depending on the digit, the proximodorsal process becomes slightly enlarge and changes its position from nearly horizontal to mostly vertical, adopting a lipshaped appearance; and (10) pedal unguals with a rounded, large foramen on the medial side* and a deep ventral fossa that surrounds a strongly developed, ridge-like flexor tubercle."

Pedal unguals of (left to right) intended "Paraxenisaurus normalensis" paratype BENC30/2-001 right digit II, right digit III and intended "Paraxenisaurus normalensis" holotype BENC 2/2-001 left digit IV in (top to bottom) right, left, proximal and dorsal views (after Serrano-Brañas et al., 2020).  Green lines point to supposedly natural median foramen

Ventral curvature is plesiomorphic, the unguals of BENC 30/2-001 are not broader than other ornithomimosaurs', and ventral angling with the proximal end held vertically is common in theropods and present in e.g. Garudimimus and Beishanlong.  The proximodorsal process "changing its position" is using a difference between 30/2-001's mostly horizontal processes and the intended holotype's more vertical process as character, which in itself presupposes they are the same taxon.  The ventral fossa surrounding a ridge-like flexor tubercle is also present in Harpymimus, Garudimimus, Beishanlong and large Dinosaur Park unguals (NMC 1349, RTMP 1967.19.145) and is not shown in the intended holotype but is claimed to be "partially broken."  This leaves the medial foramen, which might be a valid character in unguals III and IV (II is damaged in that area), but might also be taphonomic, as there are many other small circular areas of damage (e.g. center of proximal surface of ungual IV).  While the two unguals in 30/2-001 are similar to each other, that of the intended holotype is more strongly curved, has that smaller more dorsally angled proximodorsal process, is wider in proximal view, and lacks the expanded ventral half characteristic of ornithomimosaurs that is present in the other specimen.  But even if these two pedal unguals are correctly referred, they are all that's present in specimen BENC 30/2-001.  So they get us nowhere in determining caudal, manual (besides proximal manual phalanx II-2 or III-3) or femoral morphology.

The final issue I noticed was the emphasis on "Paraxenisaurus" having a first pedal digit.  This would ironically be unlike Deinocheirus, but plesiomorphically shared with Nedcolbertia, "Grusimimus", Garudimimus, Beishanlong, Archaeornithomimus and Sinornithomimus.  The character state is based on metatarsal II, where "a facet on the posterior surface of the distal quarter of this shaft, indicates the presence of an articulation area for metatarsal I." The figure shows a longitudinal groove extending down the posterior center of distal metatarsal II, which as anyone who has scored taxa for Clarke's bird matrix could tell you, is not how non-birds attach their hallux to the metatarsus.  Hattori (2016) for instance writes in Allosaurus "there is no attachment scar corresponding to the metatarsal I fossa on either medial or plantar aspect of MT II" and in Citipati "there is no obvious attachment scar of MT I on either medial or plantar aspect of MT II."  Serrano-Brañas et al. state "in Garudimimus brevipes ... the attachment site is also placed in the same area as in Paraxenisaurus normalensis", but the feature in Garudimimus is a raised scar with sharp medial demarcation from the shaft.  As Middleton (2003) recognized, this scar is for the m. gastrocnemius, specifically the m. gastrocnemius pars medialis (Carrano and Hutchinson, 2002), and I'll note it's present even in Gallimimus which lacks pedal digit I (Osmolska et al., 1972: Plate XLIX Fig. 1b).  "Paraxenisaurus"'s groove is then more likely to be the m. flexor digitorum longus II tendon, which "passed through the ventral groove in its respective metatarsal to insert serially on each of the pedal phalanges" in e.g. Tyrannosaurus (Carrano and Hutchinson, 2002).  


Left metatarsal II in ventral view of (left to right) intended "Paraxenisaurus normalensis" holotype BENC 2/2-001 (after Serrano-Brañas et al., 2020; yellow arrow points to supposed articulation for metatarsal I), Garudimimus brevipes holotype IGM 100/13 (after Kobayashi and Barsbold, 2005; line points to supposed articulation for metatarsal I), Gallimimus bullatus ZPAL MgD-I/94 (after Osmolska et al., 1972), and Tyrannosaurus rex FMNH PR2081 (after Brochu, 2003).


What exactly is "Paraxenisaurus"?  Comparison is hindered by the specimens being figured mixed together, and the figures are not in numerical order in the preprint, being shown in the order of- 1, 10-19, 2, 20-23, 3-9.  In addition, the scale bars vary within the same figure (e.g. phalanx IV-1 is proximally ~61 mm wide in figure 14a but ~93 mm wide in figure 14e) and the listed measurements are different yet (e.g. IV-1 is listed as 83 mm wide).  Thus any composite reconstruction is necessarily approximate.  The supposed manual element is too fragmentary to give much information, but it is of the appropriate size and shape to be a proximal pedal phalanx I-1.  This would make more sense preservationally since the other material preserved in the specimen is all from the tarsus and pes.  It's a shame the astragalocalcaneum is not described better or figured in more views, as the dorsal (= proximal?) perspective has many broken surfaces and edges, so that e.g. the small calcaneum might be preservational.  The fused proximal tarsals are like ceratosaurs, deinocheirids (Deinocheirus plus Hexing), alvarezsaurids and caenagnathids.  Having any sense of the ascending process morphology could tell us much.  Metatarsal II is not obviously deeper than wide, unlike ornithomimosaurs (except Harpymimus; unreported in deinocheirids), but like carcharodontosaurids, therizinosauroids, some oviraptorids and velociraptorines.  The proximal outline of metatarsal III would at first glance appear to be the strangest thing about this material, being reconstructed as strictly dorsoventrally oval unlike all(?) other theropods.  Tilting it and adding a posterior tapered tip results in a close match to Majungasaurus however (see figure below).  If it is an unreduced proximal metatarsal III, tyrannosauroids, most ornithomimosaurs, alvarezsauroids and pennaraptorans would be excluded.  Proximal phalanx II-2 lacks a proximoventral heel, so is not from a deinonychosaur.  The pedal phalanges are too elongate to be therizinosauroid, and the pedal ungual is too broad.  Phalanges are not as dorsoventrally compressed as Mapusaurus, and as noted above they lack the ventrolateral shelves found in ornithomimosaurs.  Abelisaurid phalanges seem similar however.  I wonder if we have a case like Camarillasaurus or probably Dandakosaurus involving misidentified elements making the specimen seem stranger than it really was, with so many edges of supposed metatarsal III dotted to indicate incompleteness that it could actually be metatarsal II or IV.  Certainly nothing connects this specimen with Deinocheirus.  As per the numerous errors illustrated by Hartman et al. (2019) nobody should trust Choiniere et al.'s scorings in any case.  The Lori matrix recovers "Paraxenisaurus" as a ceratosaur closest to Aucasaurus as far as taxa with well preserved feet are concerned, but also doesn't include characters particular to ceratosaurs and isn't great with pedal characters in general.  So I would place the specimen as Neotheropoda incertae sedis (or even indet.) pending a better description of the tarsus and of the real bone surfaces on supposed proximal metatarsal III. 

Pes of "Paraxenisaurus normalensis" holotype (center) in dorsal view compared to Majungasaurus crenatissimus composite (left) and Deinocheirus mirificus referred specimen IGM 100/127 (right).  Colored proximal view of "Paraxenisaurus" is after Serrano-Brañas et al., with reoriented metatarsal III as per my interpretation shown above that.  Note "Paraxenisaurus" elements were scaled using their scale bars, whereas scaling to listed measurements results in different proportions, so those should be seen as approximate.  "Paraxenisaurus" after Serrano-Brañas et al. (2020), Majungasaurus after Carrano (2007) and Deinocheirus after Lee et al. (2014).


References- Osmólska, Roniewicz and Barsbold, 1972. A new dinosaur, Gallimimus bullatus n. gen., n. sp. (Ornithomimidae) from the Upper Cretaceous of Mongolia. Palaeontologica Polonica. 27, 103-143.
Carrano and Hutchinson, 2002. Pelvic and hindlimb musculature of Tyrannosaurus rex (Dinosauria: Theropoda). Journal of Morphology. 253, 207-228.

Brochu, 2003. Osteology of Tyrannosaurus rex: Insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull. Society of Vertebrate Paleontology Memoir. 7, 138 pp.


Middleton, 2003. Morphology, evolution, and function of the avian hallux. PhD thesis, Brown University. 147 pp.

Carrano, 2007. The appendicular skeleton of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. In Sampson and Krause (eds.). Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. SVP Memoir 8, 164-179.

Lee, Barsbold, Currie, Kobayashi, Lee, Godefroit, Escuillie and Tsogtbaatar, 2014. Resolving the long-standing enigmas of a giant ornithomimosaur Deinocheirus mirificus. Nature. 515, 257-260.

Kobayashi and Barsbold, 2005. Reexamination of a primitive ornithomimosaur, Garudimimus brevipes Barsbold, 1981 (Dinosauria: Theropoda), from the Late Cretaceous of Mongolia. Canadian Journal of Earth Sciences. 42(9), 1501-1521.

Claessens and Loewen, 2016 (online 2015). A redescription of Ornithomimus velox Marsh, 1890 (Dinosauria, Theropoda). Journal of Vertebrate Paleontology. 36(1), e1034593.

Hattori, 2016. Evolution of the hallux in non-avian theropod dinosaurs. Journal of Vertebrate Paleontology. 36(4), e1116995.

Hartman, Mortimer, Wahl, Lomax, Lippincott and Lovelace, 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7:e7247.

Cau, 2020 online. http://theropoda.blogspot.com/2020/04/paraxenisaurus-un-deinocheiride.html


Serrano-Brañas, Espinosa-Chávez, Maccracken, Gutiérrez-Blando, de León-Dávila and Ventura, 2020. Paraxenisaurus normalensis, a large deinocheirid ornithomimosaur from the Cerro del Pueblo Formation (Upper Cretaceous), Coahuila, Mexico. Journal of South American Earth Sciences. 101, 102610.