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.

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.