Thursday, August 22, 2019

Therizinosaurs in the Lori matrix

Next up are therizinosaurs.  These are one of the best analyzed clades because I incorporated all of Zanno's (2010) characters, which is by far the largest and most recent analysis of the group until the Lori paper was published.  The topology is-

Falcarius is the most basal taxon shown of course, but Martharaptor was pruned a posteriori and can fall out anywhere in Therizinosauria outside the Alxasaurus plus Segnosaurus clade.  I tried including Thecocoelurus, but the Lori matrix is pretty terrible when it comes to scoring single vertebrae-

Thecocoelurus                       ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ???????(01)0? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ???1?????? ?????????? ?????2???? ?????????? ?????????? ?????????? ?????????? ???????0?? ?????????? ?????????? ?????????? ?????1???? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ??0??????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ??????????

Jianchangosaurus fell out in the same place as its original description, with Cau's (2018) placement in Alvarezsauroidea taking 18 more steps so is very unlikely.  Mine is the only published matrix besides Senter (2011) and its derivatives to use information from the second Beipaiosaurus specimen, and incorporated photos from Zanno and the new paper on the holotype skull elements too.

Beipiaosaurus inexpectus holotype (IVPP V11559) cervical vertebra in dorsal view (courtesy of Zanno).
Zanno also provided photos of Alxasaurus and Enigmosaurus, and its depressing how much of the former is lost.  Enigmosaurus rather famously was shown by Zanno to not resemble Barsbold's original illustration that was the only reference picture known for over two decades.  Placing Enigmosaurus closer to Segnosaurus than Neimongosaurus or Erliansaurus as in Zanno's tree takes 4 more steps.  Forcing Enigmosaurus and Erlikosaurus to be sister taxa to simulate the synonymy mentioned by Barsbold (1983) takes 4 steps, so seems unlikely.  The duo moves between Nanshiungosaurus and the Segnosaurus plus Nothronychus clade.  We were the first analysis to include "Chilantaisaurus" zheziangensis, which emerged in a polytomy with Alxasaurus, Enigmosaurus and therizinosaurids.

Alxasaurus elesitaiensis holotype (IVPP V88402a) chevrons in right lateral view (natural order reversed) (courtesy of Zanno).
As was the case with Archaeornithomimus? bissektensis, we didn't include the possible chimaera of Bissekty Therizinosauria as an OTU, unlike Sues and Averianov (2015).  But if you do want to experiment with it, here's the scorings.  It emerges in a polytomy in the Suzhousaurus plus Therizinosaurus clade of therizinosaurids.  Btw, Archaeornithomimus? bissektensis does fall out most parsimoniously sister to A. asiaticus when all Bissekty material is used.

'Bissekty-Therizinosauroidea'       ????1??0?? ????1????? ?????1???? ?1???????? ?????{01}1000 ?01??????? 00???????? 2??21?0??? ???????00{123} {12}00(01)2011?? ??0???0(01)00 ??11????{12}? ?{01}0?100??? ?????????? ?1{01}?0????? ??0?0???{012}0 000(01)?010?? ?????????? ?????????? ?????0{12}?00 1?0???0??0 ??0??{01}0??? 0?1??????? ????0?1?0? {01}0?1???{01}?? ??0??????? ?????????? ?????????0 ???001??00 ??00?01?1? 10???????? ?????????1 ???0?????? ???1?????? ??????0??1 0???1(12)???? ????0???1? ????0?011? ???0????0? ???0{12}0???? ????????0? 0?0????1?? ?????????? ??010101?1 ??0?0(01)???? ?????{01}010? ???100???? ????????11 1010?????? ??0??0???? ?????????? ?????????? ??????0??? ??00?????? ?00??????? ?????????? ???????0-- -??00??010 ?????????? ??????-??? ???-010??1 0100????00 10?1?00??? ???0?00??? ?????????? ????0????? ???000???? ?0???-???? ?????????? ?????001??

Enigmosaurus mongoliensis holotype (IGM 100/84) synsacrum and ilium in ventral view (courtesy of Zanno).
Next is Therizinosauridae itself, which we refined Zhang et al.'s (2001) definition of to include type species.  Therizinosaurids first split into a clade of Erliansaurus, Neimongosaurus, Suzhousaurus and Therizinosaurus.  Forcing the former two to be outside a clade of Suzhousaurus, Therizinosaurus and the taxa below, as in Zanno's tree, takes 5 more steps.  Notably, we did not include the hindlimb IGM 100/45 in the Therizinosaurus OTU since there's no overlap and its not even particularly large.  But here's the Therizinosaurus OTU including the hindlimb.  Using this version of Therizinosaurus leaves the tree basically the same but destabilizes it somewhat in that Therizinosaurus and Erlikosaurus can now go in multiple positions within Therizinosauridae, and the Nanchao embryos are in a trichotomy with the Suzhousaurus clade and the Nothronychus clade.  Is this an indication the hindlimb produces homoplasy and so might not belong to Therizinosaurus?

Therizinosaurus                     ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ????????01 0110021000 01?0001100 00001110?? ?????????? ?????????? ?????????? ???0???010 1?0000000? 0?1??1???? ?????????? ?????????? 000??0???? ??????3??1 ?????????0 ???00????? 0?1?0?1??? ?????0???? ?????????1 ?????????? ?????0???? ?????????? ?????????? 1011010101 100100??1? ????{12}?00?? 00?12110?? 101??????? 0????0?111 00?010???? ????????1? ?????????? ????100111 1101110??? ?????????? ????????1? ?1???????? ?????????1 ???0?????? ?000?????? ?????0???1 ?????????? ?????????? ?????????? ?????????? ?????0???? ??????-00? ?00-000001 0?0100??0? 10000???0{01} ?{01}?0000??0 {01}0???????? ????????00 ?00?????0- -??11-???? ?????????? ???1?0???0
Segnosaurus galbinensis paratype (IGM 100/83) cervical neural arch in right lateral view (courtesy of Zanno).
Now comes the Nanchao therizinosaur embryos, those described by Kundrat et al. inside dendroolithid eggs.  While including such young specimens might be seen as risky, my ontogenetically conservative scoring method with state N seems to have worked fine here.  They fall out where you'd expect a Santonian-Campanian therizinosaur to do so.  Following that is Nanshiungosaurus brevispinus, which Senter et al. (2012) recovered as the next most derived therizinosaur after Alxasaurus.  Forcing it into this basal position takes 4 steps.  Nanshiungosaurus? bohlini was included but pruned a posteriori since it can go anywhere in the Segnosaurus plus Nothronychus clade.  Forcing Nanshiungosaurus monophyly is just a single step longer though, while forcing bohlini to be sister to the contemporaneous Suzhousaurus takes 2 steps.

Segnosaurus itself (which Zanno also provided photos of) pairs with ex-Alectrosaurus forelimb AMNH 6368, which has only previously been analyzed by Zanno (2006) where it pairs with Erliansaurus.  Forcing that here compared to other taxa she included results in trees 3 steps longer.  Erlikosaurus groups with the Nothronychus species in a trichotomy where it can be sister to either species.  Forcing Nothronychus monophyly takes only a single step, but note that no proposed Nothronychus characters involve elements that can be compared to Erlikosaurus (humerus and pes).  Forcing Erlikosaurus to group with Therizinosaurus as in Senter et al. requires only a single step, with Erlikosaurus moving to the Therizinosaurus clade.

Next time, oviraptorosaurs...

References-  Barsbold, 1983. Carnivorous dinosaurs from the Cretaceous of Mongolia. Transactions of the Joint Soviet-Mongolian Palaeontological Expedition. 19, 117 pp.

Zhang, Xu, Sereno, Kwang and Tan, 2001. A long-necked therizinosauroid dinosaur from the Upper Cretaceous Iren Dabasu Formation of Nei Mongol, People’s Republic of China. Vertebrata PalAsiatica. 39(4), 282-290.

Zanno, 2006. The pectoral girle and forelimb of the primitive therizinosauroid Falcarius utahensis (Theropoda, Maniraptora): Analyzing evolutionary trends within Therizinosauroidea. Journal of Vertebrate Paleontology. 26(3), 636-650.

Zanno, 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology. 8(4), 503-543.

Senter, 2011. Using creation science to demonstrate evolution 2: Morphological continuity within Dinosauria. Journal of Evolutionary Biology. 24(10), 2197-2216.

Senter, Kirkland, DeBlieux, Madsen and Toth, 2012. New dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the evolution of the dromaeosaurid tail. PLoS ONE. 7(5), e36790.

Sues and Averianov, 2015. Therizinosauroidea (Dinosauria: Theropoda) from the Upper Cretaceous of Uzbekistan. Cretaceous Research. 59, 155-178.

Cau, 2018. The assembly of the avian body plan: A 160-million-year long process. Bollettino della Società Paleontologica Italiana. 57(1), 1-25.

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. DOI: 10.7717/peerj.7247 

Monday, August 19, 2019

Alvarezsaurs in the Lori matrix

This time our topology is-

I provide a new definition for Alvarezsauroidea that adds Therizinosaurus as an external specifier since I find it most parsimonious for Therizinosauria to be its sister group, and uses Alvarezsaurus as the internal specifier unlike Sereno's that uses Shuvuuia- (Alvarezsaurus calvoi < - Ornithomimus velox, Therizinosaurus cheloniformis, Passer domesticus) .  Alvarezsauroids have had a controversial phylogenetic placement, with the Lori matrix recovering them as basal maniraptorans sister to therizinosaurs.  Yet they can be outside therizinosaurs plus pennaraptorans in 3 steps, become arctometatarsalians in 4 steps (can bring therizinosaurs or not), non-maniraptoriforms in 6 steps (they bring therizinosaurs), closer to pennaraptorans than therizinosaurs in 6 steps, paravians in 11 steps (therizinosaurs move with), closer to Compsognathus than to birds in 15 steps, closer to birds than deinonychosaurs in 27 steps, and closer to Archaeopteryx and other birds than to dromaeosaurids and troodontids in 30 steps.

Fukuivenator is an odd taxon, recovered here as the basalmost alvarezsauroid.  But it can be a therizinosaurian in only two steps, and outside Maniraptoriformes in 4 steps (it emerges in Coeluridae).  One thing I don't think it is is a dromaeosaurid, as that takes 27 more steps, and getting it into Paraves or Pennaraptora requires 11 and 7 steps respectively.  Still, I wouldn't be surprised to see this taxon work its way around the base of Maniraptoriformes once an osteology comes out.

Shuvuuia deserti IGM 100/975 axial elements in ventral view and pelvis in dorsal view (courtesy AMNH).
Nqwebasaurus was recently redescribed by Sereno (2017), which I incorporated into its scorings.  Choiniere et al. (2012) recovered it in Ornithomimosauria, but note most of the characters they list to support that are also said to be present in alvarezsauroids.  Even they could place it in Alvarezsauroidea with only 4 steps.  The Lori matrix needs 6 steps to place it in Ornithomimosauria, which I think is higher partially due to it finding Pelecanimimus to be an alvarezsauroid too.  So similarities between the two like their teeth being in a common groove and maxillary teeth being confined to the anterior third of the bone are no longer ornithomimosaur-like.  As recently noted by Cerroni et al. (2019), this makes more sense biogeographically as well.  Oh, and note that the Lori matrix found Afromimus to be a ceratosaur as in that paper.  In any case, Nqwebasaurus takes 10 steps to move to Compsognathidae, and 7 steps to move sister to Pennaraptora.

As for Pelecanimimus itself, it seems plausibly alvarezsauroid if you think about it.  The skull is famously similar to Shuvuuia, the posterior tympanic recess is in the otic recess, ossified sterna are otherwise unknown for ornithomimosaurs, the long manual digit I was always out of place compared to Harpymimus, and Europe makes more sense for otherwise Gondwanan clades in the Cretaceous.  Now if only someone would release Perez-Moreno's thesis describing it in detail...

Shuvuuia deserti IGM 100/975 pectoral and forelimb elements. Note the tiny phalanx from digit II or III at the bottom (courtesy AMNH).
Patagonykus and Bonapartenykus are usually closer to parvicursorines than Alvarezsaurus and Achillesaurus, but the Lori matrix found them just outside Alvarezsauridae instead.  Interestingly, Xu et al. (2018) recovered the same results.  It takes 3 steps to move Patagonykus closer to parvicursorines, and 4 steps to join Alvarezsaurus and Patagonykus to the exclusion of parvicursorines as in Alifanov and Barsbold (2009).  Xu et al. recover these in 5 and 7 steps respectively, and the most recent version of Longrich and Currie's alvarezsaurid matrix (Lu et al., 2018) recovers a basal Patagonykus and a basal Parvicursorinae in 3 steps each.

One odd result is that the newly described Xiyunykus and Bannykus fall in Patagonykinae too.  Yet only 2 steps move them outside the Patagonykus plus Parvicursorinae clade, where they form a clade.  Another step breaks that up to place Xiyunykus more basal as in Xu et al..  Them being basal certainly fits better stratigraphically, and Xu et al. use several characters designed for alvarezsauroids that the Lori matrix didn't include yet.  Hopefully full osteologies will be published as well.

Mononykus olecranus cast YPM 56693 (of holotype) pes in plantar view (courtesy of Senter).
A patagonykine Achillesaurus as suggested by Agnolin et al. (2012) takes 7 additional steps in the Lori matrix where it instead emerges just closer to parvicursorines than Alvarezsaurus.  On the other hand, only a single step joins it with Alvarezsaurus as in Longrich and Currie (2009) and only 2 steps makes it just further from parvicursorines than Alvarezsaurus as in Xu et al. (2018).

Alnashetri is known from type hindlimb material, but now also from MPCA 377, a nearly complete specimen with interesting characters like flat and unfused sternal plates.  Makovicky et al. (2016) used this data to recover it as the sister group to Alvarezsauridae, and while the few published details left it more derived in the Lori tree, it can go to a more basal position with only two steps.  It should be interesting to compare to e.g. Bannykus once it is published.

Mononykus olecranus cast YPM 56693 (of holotype) (courtesy of Senter).
The arctometatarsal clade has a unique topology, but no other analysis has included nearly as many characters or all of these taxa, with Lu et al. omitting Albinykus and Ceratonykus among non-fragmentary specimens, and Xu et al. omitting the more recently described Qiupanykus.  Enforcing the Lori topology in Lu et al.'s matrix is only 5 steps longer, and doing so in Xu et al.'s matrix is only 6 steps longer.  On the other hand, Xu et al.'s topology is so unresolved at this level, the only difference in mine is placing the Albinykus plus Xixianykus clade basally near Albertonykus, which takes 5 steps to do in the Lori matrix.

It should be noted that Lu et al.'s illustrated topology (their Figure 3) is not their matrix's real result, as they did not fully analyze tree space.  Instead of 20 trees, there are 214 trees.  These differ in that Albertonykus, YPM 1049 and undescribed 41HIII-0104 can fall out anywhere more derived than Patagonykus, and that Parvicursor, the Tugriken Shireh taxon, Shuvuuia and Mononykus form an unresolved polytomy.  This leaves Linhenykus, Qiupanykus and Xixianykus unresolved between that polytomy and Patagonykus, which is perfectly compatible with the Lori topology.  This may also show that the small alvarezsauroid-specific matrix of Longrich and Currie is insufficient given all the new taxa described since 2009.  YPM 1049 was far too fragmentary to include (distal metatarsal III) but I tried testing undescribed Quipa specimen 41HIII-0104.  Didn't make it into the publication, but here's its scorings-

'41HIII0104'                        ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ???????-?? ?????????1 ?10??????? ?????????? ?????????? ???0?????? ????1????? ???1?????{01} ?????????? ?????????? ?????????? ????????0? ????????3? ?????????? ?????????? ?????????? ?????????? ?????????1 ?????????1 1????????? 1????????? ?????????? ?????????? ?????????? ???1?????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ????????0? ?????????? ?????????? ?????????? ?????????? ?????????? ???1?????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????{123}???? ?????????? ?????????? ?????????? ?????????? ?????????? ??1???0???

Tugriken Shireh parvicursorine (IGM 100/99) vertebrae and ilia in ventral view, forelimb and fibula in lower right (courtesy AMNH).
Interestingly, Agnolin et al., Xu et al. and the Lori analysis all recovered Albinykus sister to Xixianykus outside Parvicursorinae.  Wonder if that's a real signal?  Unfortunately, the only attempt to name this clade was Agnolin et al. who also recovered Ceratonykus in there and called it Ceratonykini.  Xu et al. place Ceratonykus closer to parvicursorines, while I found it more basal than either, sister to Qiupanykus which neither of the other studies used.  Forcing Ceratonykus sister to Albonykus plus Xixianykus takes 3 more steps in the Lori matrix.  Forcing Ceratonykus sister to Mononykus as in its original description (with or without Qiupanykus) takes 5 more steps.  As stated in the paper, we were the first analysis to include Hateg tibiotarsi Bradycneme and Heptasteornis.  While the former can fall into many positions in Maniraptora, the latter was resolved as an alvarezsaurid as proposed by Naish and Dyke (2004).  Note this used only the tibiotarsus and not alvarezsaurid-like distal femur FGGUB R.1957.  A single step moves Heptasteornis to Troodontidae.

We also provide an updated definition for Parvicursorinae (Mononykus olecranus + Parvicursor remotus), like Choiniere et al.'s (2010) but using species.   One accident of our definitional and discovery history is that all these newer arctometatarsal alvarezsaurids (Xixianykus, Albertonykus, Albinykus, Linhenykus, Qiupanykus, Ceratonykus, etc.) emerge outside the originally discovered and defined Parvicursorinae.  We could really use some clade defining taxa closer to Mononykus than Patagonykus, Alvarezsaurus or Achillesaurus.  In any case, I got a lot of experience with parvicursorine specimens, examining Shuvuuia and the Tugriken Shireh specimen IGM 100/99 in person, and having photos of high quality casts of Mononykus thanks to Senter.  I found the Tugriken Shireh taxon closer to Shuvuuia, but moving it closer to Parvicursor as in Longrich and Currie is just 1 step longer.

Tugriken Shireh parvicursorine (IGM 100/99) vertebrae and ilia in dorsal view, forelimb and fibula in lower right (courtesy AMNH).
Next time, therizinosaurs...

References-  Naish and Dyke, 2004. Heptasteornis was no ornithomimid, troodontid, dromaeosaurid or owl: The first alvarezsaurid (Dinosauria: Theropoda) from Europe. Neus Jahrbuch für Geologie und Paläontologie. 7, 385-401.

Alifanov and Barsbold, 2009. Ceratonykus oculatus gen. et sp. nov., a new dinosaur (?Theropoda, Alvarezsauria) from the Late Cretaceous of Mongolia. Paleontological Journal. 43(1), 94-106.

Longrich and Currie, 2009. Albertonykus borealis, a new alvarezsaur (Dinosauria: Theropoda) from the Early Maastrichtian of Alberta, Canada: Implications for the systematics and ecology of the Alvarezsauridae. Cretaceous Research. 30(1), 239-252.

Choiniere, Xu, Clark, Forster, Guo and Han, 2010. A basal alvarezsauroid theropod from the early Late Jurassic of Xinjiang, China. Science. 327, 571-574. 

Agnolin, Powell, Novas and Kundrat, 2012. New alvarezsaurid (Dinosauria, Theropoda) from uppermost Cretaceous of north-western Patagonia with associated eggs. Cretaceous Research. 35, 33-56.

Makovicky, Apesteguia and Gianechini, 2016. A new, almost complete specimen of Alnashetri cerropoliciensis (Dinosauria: Theropoda) impacts our understanding of alvarezsauroid evolution. XXX Jornadas Argentinas de Paleontologia de Vertebrados. Libro de resumenes, 74.

Sereno, 2017. Early Cretaceous ornithomimosaurs (Dinosauria: Coelurosauria) from Africa. Ameghiniana. 54, 576-616.

Lu, Xu, Chang, Jia, Zhang, Gao, Zhang, Zhang and Ding, 2018. A new alvarezsaurid dinosaur from the Late Cretaceous Qiupa Formation of Luanchuan, Henan Province, central China. China Geology. 1, 28-35.

Xu, Choiniere, Tan, Benson, Clark, Sullivan, Zhao, Han, Ma, He, Wang, Xing and Tan, 2018. Two Early Cretaceous fossils document transitional stages in alvarezsaurian dinosaur evolution. Current Biology. 28, 1-8. DOI: 10.1016/j.cub.2018.07.057

Cerroni, Agnolin, Egli and Novas, 2019. The phylogenetic position of Afromimus tenerensis Sereno, 2017 and its paleobiogeographical implications. Journal of African Earth Sciences. DOI: 10.1016/j.jafrearsci.2019.103572

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. DOI: 10.7717/peerj.7247

Saturday, August 10, 2019

Ornithomimosaurs in the Lori matrix

Next up is Ornithomimosauria.  The Theropod Database has been updated with new ornithomimosaur info too.  The published cladogram here is-

I included the Angeac taxon as an OTU, which had very few illustrated elements at the time of scoring- the cervical, tibia and distal metatarsus with a few other reported details like the toothless dentary.  It emerged as an ornithomimosaur but since then good views of the known material have been made public and it's pretty obviously a ceratosaur similar to Limusaurus or Elaphrosaurus.  This was always an easy possibility in the matrix, as it can move to Ceratosauria in the published matrix with only two steps.  After rescoring it for the more complete remains, the Angeac  taxon emerges in Ceratosauria sister to Deltadromeus.  Here's its new scorings

????????1? ?????????? ?????????? ?????????? ?????????? 0????????? ?????????? ???2??0??? ?????????- ????--???? ??0?0??10? ???{01}??0??0 000?1?1{01}0? ???????{01}01 ?01?02{01}0?{01} ?????????? ????????11 1000?0?110 1100??{12}?00 ?1?10?1000 1??0??001? ??0??000{01}0 ???001???? ???0?????? {01}?021??0?1 ?0?110???? ?000?0{012}0?? ??{01}0???1?? ?????0?002 ??1?0?0??0 ??100?0?0? ??????11{01}1 ?????????? 1??1??{23}??? ?????????? ????-22?00 1001??0??? ?????????? 0??0011??? ?2000????? ?0?????00? ?0?000??0? ????{12}???0? ????000??? ??0-?1???? 0?1?1{01}???? ??1-?????0 ?0?????0?? ??00010?0? ?00??????? 0???????00 ???011???? ??00?????? ??0???0??0 ??0??????? ?????????? ?????????? ????0??010 ?????????? ???000-?0? ?0?-01?00? ???1?0??{01}? ??0?1????? ?????????? ??000?-?1? 00???0?{01}?? ???000???- -??00-???? ??????0??0 0???????0?

When Angeac moves in the new matrix with added taxa, we get a little change where Harpymimus is more basal and the polytomy is resolved-

Btw, I published a list of phylogenetic definitions in the supplementary material, including the first to define Ornithomimosauria on the type species- (Ornithomimus velox < - Tyrannosaurus rex, Shuvuuia deserti, Therizinosaurus cheloniformis, Oviraptor philoceratops, Troodon formosus, Passer domesticus).

Ours is one of the few published studies using the new Deinocheirus skeletons, and unlike Lee et al. (2014) I recovered it basal to garudimimids and any other ornithomimosaurs except for Hexing.  It only takes 4 steps to move with other toothless ornithomimosaurs, so that's still quite possible.  What seems implausible is it being a garudimimid, as that takes 14 steps.  The supporting evidence for that in Lee et al.'s analysis was never great, and as shown in the Sciurumimus section the scoring in Choiniere's analysis is pretty bad.

This is the first time Hexing has been in an analysis besides the ornithomimosaur-only one in its original description, which did not include Deinocheirus.  It groups with Deinocheirus, which is funny because of the size difference, but there would have to be something to fill up that ghost lineage if Deinocheirus is so basal.

Shenzhousaurus and Harpymimus are next.  Kinnareemimus takes three steps to move to Ornithomimosauria in the old matrix, but only one step in the new matrix.  It emerges in a trichotomy with Shenzhousaurus and Harpymimus. An extra step moves it to Alvarezsauroidea, so that's still pretty uncertain.

Archaeornithomimus asiaticus paratype left femur in posterior view (AMNH 21800) (Courtesy AMNH).

While I didn't recover Deinocheirus by Garudimimus, I did get Beishanlong there as in Lee et al..  Also interesting is that Archaeornithomimus groups there.  That genus is known from a whole ton more specimens than suggested by Smith and Galton (1990), which I was able to examine at the AMNH.  There are whole boxes of tibiae, and metatarsals, and phalanges, that could really use a new osteology.  Where's Archaeornithomimus bissektensis you ask?  Its holotype femur went way too many places to include, lacking a unique combination of scores.  Sues and Averianov (2015) did assign a lot of Bissekty material to the taxon, but I didn't include any of the Bissekty isolated composite taxa in case they're chimaerical.  I still scored them though, so if anyone wants to experiment, the Bissekty Ornithomimosauria is-

???????0?? ?????????? ?????????? ?????????? ?????{01}0000 ?0???????? ?????????? ?????????? ?????????? ?????????? ??011010(01)0 ?011????0? 0?0??0???? ?????????? 10{01}0?2{01}00? ?01??0??{01}1 0??1?0???? ?0?0?0?00? ?????????? ?????01000 1100210000 1100000020 ?????????? ????0????? ???2?0?1?? 0???0????? ?00??0??0? ??00?????0 ???10??00? 1?1??????? ????0???0? ????????11 ?????????? ??010????? ??????0??? ?????2???? {01}???0?0?01 ??????10?? ???0?11??? ?210?????? 1??????00? 0????0?0?1 ????????0? ??1?000??? ?????0???? ??1??{01}001? ??1??00??0 10??????10 0(01)1000?0?0 ?????0???? 0???????0? ???1?????? ??0?0??0?? ??00?????? ?????????? ?????????? ?????????? ???00??010 ??0?-????? ??????-?00 ?00-010??1 -11100??00 ???????--? ???00?00?? 0?00?????? ?00?000100 0{01}0000???- -???{01}--??? ??-?0????? ?10?100??0

Archaeornithomimus? bissektensis holotype right femur (CCMGE 726/12457) (Courtesy of Averianov).

 The "Grusimimus" specimen GIN 960910KD ends up in Garudimimidae too, despite generally being seen as a potential juvenile Harpymimus.  Joining the two takes 4 steps, so is still quite possible.  I wonder if this really is an endemic Asian clade.  Interestingly, Arkansaurus (which we were able to score based on the new description) is a basal garudimimid here, but it can move either a node outside the garudimimid plus ornithomimid clade, or to Ornithomimidae or to Tyrannosauroidea (where it ends up similar to where Suskityrannus was placed by its authors) with one step.  The Lori matrix isn't that great with pedal characters yet.

We also provide a definition for Ornithomimidae using O. velox and not dependent on the controversial Deinocheirus- (Ornithomimus velox < - Garudimimus brevipes). At the base of Ornithomimidae, we have Nedcolbertia.  While an ornithomimosaurian Nedcolbertia's been recently proposed by Brownstein (2017) and Hunt and Quinn (2018), this is the first published analysis to find the result.  That being said, only 3 steps move it outside Maniraptoriformes, where it falls out by Zuolong and megaraptorans.  Guess there was some real signal keeping it outside Tyrannoraptora in Dal Sasso and Maganuvo's (2011) TWiG analysis.  Brusatte's redescription should shed light on Nedcolbertia's anatomy, as should the description of BYU 19114 from the Cedar Mountain Formation, said to be similar by Hunt and Quinn. 

Interestingly, Ornithomimus velox does not group with Dromiceiomimus (which includes O. edmontonicus here), but is instead down by Sinornithomimus.  The only character really grouping traditional Ornithomimus species together is metacarpal I being longer than metacarpal II, which was not a character in the Lori matrix but it still takes 3 steps to combine them.  Note Claessens and Loewen (2015) in their excellent redescription just assume Ornithomimus sensu lato is monophyletic based on the metacarpal length, and I don't think anyone's actually used O. velox as its own OTU before this.  It would be funny if Sinornithomimus ended up actually being the Chinese sister taxon to OrnithomimusAepyornithomimus is sister to this pair in the published matrix, but in a trichotomy with Ornithomimus, Sinornithomimus and more derived taxa in the new version (not shown).  It wasn't resolved in its original description's analysis using the Choiniere matrix, merely more derived than Archaeornithomimus.

Next is a novel clade of Tototlmimus and "Gallimimus" "mongoliensis", the first time the latter has been included in an analysis.  Only 3 steps are needed to move it sister to Gallimimus bullatus, and Tototlmimus follows.  Tototlmimus was poorly resolved in its initial analysis based on Kobayashi characters.  Another new clade follows- Rativates plus Kaiparowitz supposed O. velox specimen MNA Pl.1762A plus "Ornithomimus" sedens, the latter based only on the holotype.  Again, Rativates has only been analyzed once before in its initial description, using Choiniere's heavily misscored matrix, while sedens and the Kaiparowitz specimen have never been analyzed before.

Ornithomimosaur coracoids in right lateral and proximal views. Top left- Beishanlong (after Makovicky et al., 2010). Bottom left- Anserimimus (after Barsbold, 1988). Top right- Sinornithomimus (after Kobayashi, 2004). Bottom right- Gallimimus (after Kobayashi, 2004). Peach dot indicates coracoid tubercle, green line indicates lateral edge of infraglenoid buttress.

Here's probably a good place to say that ornithomimosaur phylogeny has suffered a similar fate to coelurosaur phylogeny lately because everyone reuses Kobayashi's characters and scores just like how everyone reuses TWiG characters and scores.  So everyone gets an Anserimimus plus Gallimimus clade, then an American clade of Struthiomimus and 'Ornithomimus'.  But the former clade is only based on two coracoid characters, both of which are flawed.   Above on the right we have Kobayashi's (2004) figure 88 from his thesis illustrating the characters.  Top right is Sinornithomimus and bottom right is Gallimimus.  The first character is "laterally offset infraglenoid buttress of the coracoid", represented by how much the green curve protrudes downward here.  A bit more in Gallimimus, but compare to the then unknown Beishanlong coracoid in the upper left.  It has a hugely protruding process but isn't a part of the Anserimimus plus Gallimimus clade.  It's not a commonly shown perspective, but is also found in Nqwebasaurus, Allosaurus, etc..   The second character is "biceps tubercle positioned more anterior to base of posterior process", which is the peach dot in the figure.  Here note that Beishanlong also has this anteriorly positioned, but more problematically Anserimimus in the lower left does not.  Maybe the drawing's wrong, but the rest of that figure seems accurate (e.g. the manus) and detailed unlike some of the more schematic ones in Barsbold's works (e.g. Adasaurus' pelvis).  Note that the more recent Xu et al. (2011) ornithomimosaur analysis that finds the Kobayashi arrangment misscores Beishanlong for both characters.  Instead, the Lori analysis (and my previous unpublished TWiG analysis incorporating Kobayashi's and other ornithimomid-relevent characters) recovers a Struthiomimus plus Gallimimus clade and an Anserimimus plus Dromiceiomimus clade.  Forcing my pairing of these four in Xu et al.'s matrix only adds 2 steps, but getting the standard Kobayashi arrangement of them in my matrix takes 8 steps, so here I think I really might be on to something.

Tyrannoraptoran femora in lateral and/or anterior views. Top left- Xiongguanlong (after Li et al., 2010). Top right- Alioramus (after Brusatte et al., 2012). Center- Timimus (after Benson et al., 2012). Bottom left- Archaeornithomimus (courtesy AMNH). Bottom right- Garudimimus in lateral view (after Kobayashi and Barsbold, 2005) and Gallimimus in anterior view (after Osmolska et al., 1972).  Peach indicates accessory trochanter in anterior view, green outline indicates accessory trochanter in lateral view.

Also in the Struthiomimus plus Gallimimus group, we get Timimus as the sister taxon to the latter genus.  But of course Timimus was reassigned to Tyrannosauroidea by Benson et al. (2012).  So what gives?  Well, if you look at Benson et al.'s reasoning for rejecting an ornithomimosaurian identification, they say "The morphology of the accessory trochanter and the relatively anteroposteriorly narrow lesser trochanter of NMV P186303 are similar to those of derived tyrannosauroids such as Xiongguanlong and tyrannosaurids. They are unlike the anteroposteriorly broad, ‘aliform’ lesser trochanter and prominent, triangular accessory trochanter of allosauroids, ornithomimosaurs ..."  "NMV P186303 lacks several features present in all ornithomimosaurs, such as the ‘aliform’ lesser trochanter and prominent accessory trochanter. In contrast, the lesser trochanter of some tyrannosauroids is anteroposteriorly narrower, and the accessory trochanter forms a transversely thickened region, similar to the condition in T. hermani (e.g., Tyrannosaurus)."  "T. hermani also possesses a proximomedially inclined (‘elevated’) femoral head, a synapomorphy of derived tyrannosauroids (e.g., Tyrannosaurus; Xiongguanlong), that is absent in ornithomimosaurs." 

First of all, Gallimimus has an elevated femoral head too (Osmolska et al., 1972: Plate XLVII).  Not as much as most tyrannosauroids', but neither does Timimus.  Of course tyrannosauroids have always been recognized as having aliform anterior trochanters as well, so this is a matter of degree.  Their figure 19B does look anteroposteriorly narrower (~49% of total femoral width; ~49% in Xiongguanlong, ~52% in Alioramus), unlike Archaeornithomimus (~69%).  But Garudimimus' ratio is ~50%.  Also note figure 19C, also labeled as lateral view, looks broader (~64%) and no doubt had a slightly more anterior angle to the photo.  Even ignoring Garudimimus, something that depends so heavily on exact angle of perspective, especially considering taphonomy and how theropod femoral heads phylogenetically vary in their anterior angle compared to the distal end (basal forms are famously more anteromedially directed), is not great evidence in my opinion.  What about that accessory trochanter?  I agree Timimus' is more tyrannosauroid in side view, but ironically because they're larger than at least Archaeornithomimus and Gallimimus (green highlight), contra Benson et al.'s statement.  And again some ornithomimosaurs like Garudimimus have large accoessory trochanters too.  Regarding transverse width, I can't see a difference between e.g. Alioramus and Gallimimus above (peach highlight).  I certainly wouldn't say Alioramus' is thicker.  So is Timimus a tyrannosauroid or an ornithomimosaur?  I don't think the evidence is great either way, and certainly no published analysis scores for these difficult to quantify degrees of trochanter size.  Honestly, the biostratigraphy makes me think it will ultimately be some coelurosaur convergent with both.  Maybe something like Aniksosaurus, also Gondwanan Early Cretaceous with a tall and narrow anterior trochanter.

Finally, Qiupalong joins the Anserimimus plus Dromiceiomimus clade. In its description, it grouped in the American clade, but that's the same Xu et al. (2011) analysis noted above that misscores Beishanlong as lacking the supposed Anserimimus plus Gallimimus characters.

So that's the Ornithomimosauria.  I think the Lori analysis does a good job here doing one of the things it's meant to- include a ton of taxa that have either never been analyzed or were only added singly and separately to existing analyses.  Another point I like to emphasize is the hidden instability of our consensus.  You might be thinking 'well your analysis seems very poorly supported if all of these tested changes only take 3 to 4 steps each'.  Yet you can rearrange the entire tree of Xu et al.'s (2011) ornithomimosaur analysis to my topology and it just needs 5 more steps in total.  And Brusatte et al.'s (2014) tree doesn't even find resolution between Harpymimus, Beishanlong, Garudimimus, Archaeornithomimus, Sinornithomimus and the derived clade.  Overall I'd say this is the best ornithomimosaur analysis published, in taxon number, character number and robusticity of results.

Next, alvarezsauroids...

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.

Barsbold, 1988. A new Late Cretaceous ornithomimid from the Mongolia People’s Republic. Journal of Paleontology. 1988(1), 122-125.

Smith and Galton, 1990. Osteology of Archaeornithomimus asiaticus (Upper Cretaceous, Iren Dabasu Formation, People's Republic of China). Journal of Vertebrate Paleontology. 10(2), 255-265.

Kobayashi, 2004. Asian ornithomimosaurs. PhD thesis. Southern Methodist University. 340 pp.

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.

Li, Norell, Gao, Smith and Makovicky, 2010. A longirostrine tyrannosauroid from the Early Cretaceous of China. Proceedings of the Royal Society B. 277(1679), 183-190.

Makovicky, Li, Gao, Lewin, Erickson and Norell, 2010. A giant ornithomimosaur from the Early Cretaceous of China. Proceedings of the Royal Society B. 277, 191-198.

Dal Sasso and Maganuco, 2011. Scipionyx samniticus (Theropoda: Compsognathidae) from the Lower Cretaceous of Italy: Osteology, ontogenetic assessment, phylogeny, soft tissue anatomy, taphonomy, and palaeobiology. Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano. 281 pp.

Xu, Kobayashi, Lu, Lee, Liu, Tanaka, Zhang, Jia and Zhang, 2011. A new ornithomimid dinosaur with North American affinities from the Late Cretaceous Qiupa Formation in Henan Province of China. Cretaceous Research. 32(2), 213-222.

Benson, Rich, Vickers-Rich and Hall, 2012. Theropod fauna from Southern Australia indicates high polar diversity and climate-driven dinosaur provinciality. PLoS ONE. 7(5), e37122.

Brusatte, Carr and Norell, 2012. The osteology of Alioramus, a gracile and long-snouted tyrannosaurid (Dinosauria: Theropoda) from the Late Cretaceous of Mongolia. Bulletin of the American Museum of Natural History. 366, 197 pp.

Brusatte, Lloyd, Wang and Norell, 2014. Gradual assembly of avian body plan culminated in rapid rates of evolution across the dinosaur-bird transition. Current Biology. 24(20), 2386-2392. DOI: 10.1016/j.cub.2014.08.034

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.

Claessens and Loewen, 2015. A redescription of Ornithomimus velox Marsh, 1890 (Dinosauria, Theropoda). Journal of Vertebrate Paleontology. e1034593 DOI: 10.1080/02724634.2015.1034593

Sues and Averianov, 2015. Ornithomimidae (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan. Cretaceous Research. 57, 90-110.

Brownstein, 2017. Redescription of Arundel Clay ornithomimosaur material and a reinterpretation of Nedcolbertia justinhofmanni as an "ostrich dinosaur": Biogeographic implications. PeerJ 5:e3110. DOI: 10.7717/peerj.3110

Hunt and Quinn, 2018. A new ornithomimosaur from the Lower Cretaceous Trinity Group of Arkansas, Journal of Vertebrate Paleontology. e1421209. DOI: 10.1080/02724634.2017.1421209

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. DOI: 10.7717/peerj.7247

Thursday, August 8, 2019

Basal coelurosaurs in the Lori matrix

Okay, I'm on vacation and one of those goals is to get these blog posts out about the results of the Hesperornithoides analysis of Hartman et al. (2019), and the Theropod Database updated again.  With that in mind, here's our first section.

Aristosuchus was analyzed, but is not in the cladogram.  We found it to be a coelurosaur closer to Aves than Megaraptora, excluded from Maniraptoriformes.  So it could be a basal tyrannosauroid or a compsognathid, or something in between. 

I was able to examine the Ornitholestes holotype at the AMNH twice, and get some nice photos I've been posting here over the years.  Besides taking 10 steps to move to Tyrannosauroidea, it takes 7 steps to move outside Tyrannoraptora, 13 steps to move to Maniraptora, and a whopping 30 steps to move to Dromaeosauridae.  Should be the nail in the coffin for that idea.

Sinocalliopteryx emerged basal to compsognathids, but moves to Compsognathidae in 4 steps and joins basal tyrannosauroids in 1 step.  Might be worth reexamining its relationship with Dilong.

Huaxiagnathus and Juravenator join to form a clade basal to compsognathids, but can join that family in a single step.  They take 7 steps to move closer to Dilong, so are probably not tyrannosauroids.

Archaeornithoides is a highly controversial taxon, which I was the first to include in a published analysis.  While it most parsimoniously is down here at the compsognathid-grade, only 1 step moves it to Paraves.  There it groups with Xiaotingia and Mei as a sinovenatorine instead of by any known Djadochta troodontids. 

Aniksosaurus emerged down here too, more crownward than its original description.  There, Martinez and Novas (2006) proposed Aniksosaurus was a coelurosaur outside Maniraptoriformes, the latter containing tyrannosaurids in their phylogeny.  While not included in a phylogenetic analysis, they did list three characters supporting this placement.  "Distal tibia with astragalar surface proportionally low" is also true in basal tyrannosauroids (Coelurus, Guanlong) and maniraptoromorphs (Aorun, Compsognathus, alvarezsauroids including Nqwebasaurus).  "Insertion of the M. caudifemoralis longus extensive and deep"  is plesiomorphic for maniraptoromorphs, also being found in Ornitholestes, Juravenator and all ornithomimosaurs.  Robust limb elements were stated to resemble carnosaurs and megalosauroids more than most coelurosaurs, specifically the humerus, ulna, femur, tibia and pes.  The humerus is also robust in compsognathids and alvarezsaurids, while the metatarsus is less robust than Ornitholestes, therizinosaurs or Deinocheirus.  However, any measure of basic robusticity such as femoral circumference should also account for size correlation as larger taxa are typically less gracile than smaller taxa.  Brusatte (2013:395) stated "it is unclear if it possesses any clear coelurosaurian characters" so did not include it in his TWiG analysis.  However, every analysis including Aniksosaurus has recovered it within Coelurosauria, and only unquantified appendicular robusticity has even been suggested to validly support a more rootward placement than Tyrannoraptora.  While I've previously suggested some alvarezsauroid-like characters (e.g. large presacral neural canals*, ventrally keeled proximal caudal centra, transversely broad manual ungual I*, laterally expanded brevis shelf*, distally projecting lateral femoral condyle), enforcing this result in the Hartman et al. matrix adds 9 steps.  However, the asterisked characters were not included, so it could potentially only be 6 steps longer.

Scipionyx gets a pretty traditional position with not much to say.

Tugulusaurus is a compsognathid here but is historically a very basal coelurosaur, and more recently an alvarezsauroid by Xu et al. (2018).  Check the Database for details, but basically I found basal placements were due to the same three characters, which probably converged in derived tyrannoraptorans and derived maniraptoromorphs.  The position in Alvarezsauroidea was based on four characters I didn't examine ("strong medial tab on metacarpal [I]"; "dorsolaterally and dorsomedially facing lateral and medial surfaces of phalanx [I]-1 that are shallowly concave"; "axial furrow along the flexor surface of phalanx [I]-1"; "partially enclosed ‘flexor notches’ on the medial and lateral surfaces of the proximal end of the ventral surface of manual ungual [I]-2"), while it takes 5 more steps to force as an alvarezsauroid in the Lori matrix.  Thus the true difference between a compsognathid and alvarezsauroid placement could be as low as a single step.

Sinosauropteryx is also fairly boring, but photos of NIGP 127587 sent by Senter show that some aspects of its figures in Currie and Chen (2001) aren't preserved in the actual material.

Santanaraptor gets another long entry, regarding the evidence for tyrannosauroid affinities.  Basically almost all of the claimed characters don't exist in Santanaraptor or are impossible to check based on published material and that sent by Bruno Campos. 

Haplocheirus was a surprise as a compsognathid.  I know I've seen it outside Alvarezsauroidea in more analyses than Lee and Worthy (2011).  Any of you readers remember which?  One interesting thing I noticed when moving this entry is that the supposedly autapomorphic dorsally expanded anterior dentary with enlarged teeth is present in all other compsognathids, but the character wasn't included in the Lori analysis.  That's always a good sign when it comes to a position's plausibility.

Compsognathus takes 8 steps to be maniraptoran, 13 to be tyrannosauroid and 15 to be outside Tyrannoraptora.  While I did not split the specimens as separate OTUs, they do differ in 16 characters, so I plan to in the future. 

Sciurumimus gets a HUGE section in the supplementary info of the Lori paper.  Rauhut asked us to justify its inclusion in the analysis when it's supposed to be a megalosauroid.  So I fully reexamined Rauhut et al.''s (2012) analyses of Sciurumimus in the various analyses and found misscorings in each (Smith et al., 2008; Benson et al., 2010; Choiniere et al., 2010) were responsible for keeping it away from Compsognathus.  So there's no mystery as to why Juravenator moved to a basal position when Sciurumimus was included but was a coelurosaur when it wasn't, it's just misscorings.

Skull of NGMC 2124.
NGMC 2124 is the Sinosauropteryx sp. of Ji and Ji (1997) and has never been included in an analysis before this.  It ends up closer to other compsognathids than Sinosauropteryx, but only takes 3 steps to group with the latter genus.  I examined this one in person when it was on display at the RTMP.

Finally, we have Aorun.  Xu et al. (2018) recently proposed this is the basalmost alvarezsauroid based on four unambiguous synapomorphies- dorsoventrally flattened internarial bar; collateral ligament fossae on metacarpal I absent; manual digit I bearing large ungual and all other unguals distinctly smaller; proximodistally oriented step-like ridge on anterior surface of tibia that braces astragalar ascending process.  We recovered Aorun as a compsognathid, and found it takes 17 more steps to move to Alvarezsauroidea.  This is similar to Cau's (2018) results, where Aorun and Compsognathus are both non-tyrannoraptoran coelurosaurs and can form a Compsognathidae with no extra steps, but it takes 9 extra steps to force an alvarezsauroid Aorun.  Notably, even Xu et al.'s matrix only needs 4 steps to move Aorun to Compsognathidae.  Of Xu et al.'s proposed alvarezsauroid characters, the flattened internarial bar was used by us and is shared with the controversially compsognathid HaplocheirusAorun actually seems to have a weak medial ligament pit on metacarpal I (Choiniere et al., 2013: Fig. 15A).  The ratio between manual ungual I and II lengths (1.28) in Aorun is not more than Sciurumimus (~1.29) or Sinosauropteryx (~1.79).  Finally, the ridge bracing the astragalar ascending process is primitive for maniraptoriforms and also present in Compsognathus and Tugulusaurus.  Thus a compsognathid identity is the best supported given proposed characters.

I was curious with Tugulusaurus, Haplocheirus and Aorun each recovered as alvarezsauroid by Xu et al. and compsognathid by me, is there some unseen connection between the clades?  Enforcing them to be more closely related to each other than to other groups takes 15 more steps, so apparently it's not a great hypothesis.  

Next, ornithomimosaurs...

References- Ji and Ji, 1997. Advances in the study of the avian Sinosauropteryx prima. Chinese Geology. 242, 30-32.

Currie and Chen, 2001. Anatomy of Sinosauropteryx prima from Liaoning, northeastern China. Canadian Journal of Earth Science. 38(12), 1705-1727.

Martínez and Novas, 2006. Aniksosaurus darwini gen. et sp. nov., a new coelurosaurian theropod from the early Late Cretaceous of central Patagonia, Argentina. Revista del Museo Argentino de Ciencias Naturales. 8(2), 243-259.

Smith, Makovicky, Agnolin, Ezcurra, Pais and Salisbury, 2008. A Megaraptor-like theropod (Dinosauria: Tetanurae) in Australia: Support for faunal exchange across eastern and western Gondwana in the Mid-Cretaceous. Proceedings of the Royal Society B. 275(1647), 2085-2093. DOI: 10.1098/rspb.2008.0504

Benson, Carrano and Brusatte, 2010. A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic. Naturwissenschaften. 97(1), 71-78. DOI: 10.1007/s00114-009-0614-x

Choiniere, Clark, Forster and Xu, 2010. A basal coelurosaur (Dinosauria: Theropoda) from the Late Jurassic (Oxfordian) of the Shishugou Formation in Wucaiwan, People's Republic of China. Journal of Vertebrate Paleontology. 30(6), 1773-1796. DOI: 10.1080/02724634.2010.520779

Lee and Worthy, 2011. Likelihood reinstates Archaeopteryx as a primitive bird. Biology Letters. 8(2), 299-303. DOI: 10.1098/rsbl.2011.0884

Rauhut, Foth, Tischlinger and Norell, 2012. Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany. Proceedings of the National Academy of Sciences. 109(29), 11746-11751.

Brusatte, 2013. The phylogeny of basal coelurosaurian theropods (Archosauria: Dinosauria) and patterns of morphological evolution during the dinosaur-bird transition. PhD thesis, Columbia University. 944 pp.

Choiniere, Clark, Forster, Norell, Eberth, Erickson, Chu and Xu, 2013 [physically published 2014]. A juvenile specimen of a new coelurosaur (Dinosauria: Theropoda) from the Middle-Late Jurassic Shishugou Formation of Xinjiang, People's Republic of China. Journal of Systematic Palaeontology. 12(2), 177-215.

Cau, 2018. The assembly of the avian body plan: A 160-million-year long process. Bollettino della Società Paleontologica Italiana. 57(1), 1-25. DOI: 10.4435/BSPI.2018.01

Xu, Choiniere, Tan, Benson, Clark, Sullivan, Zhao, Han, Ma, He, Wang, Xing and Tan, 2018. Two Early Cretaceous fossils document transitional stages in alvarezsaurian dinosaur evolution. Current Biology. 28, 1-8. DOI: 10.1016/j.cub.2018.07.057

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. DOI: 10.7717/peerj.7247