‘Pennaraptora’ — avoid this junior synonym

A new volume published by the AMNH
(eds. Pittman and Xu 2020), is all about the the putative clade, ‘Pennaraptora’ (Fig. 1). According to the preface, “Pennaraptora comprises birds themselves as well as the pennaceous feathered dromaeosaurids, troodontids, scansoriopterygids, and oviraptorosaurians.”

Here
in the large reptile tree (LRT, 1727+ taxa; subset Fig. 2) scansoriopterygids are birds, not oviraptorosaurian sisters. Oviraptorosaurians are terminal taxa in a larger clade that includes therizinosaurs and the CNJ79 specimen of Compsognathus and that clade is the sister clade of the Compsognathus holotype, struthiomimids and tyrannosaurids (Fig. 2). The last common ancestor of all these clades in the LRT is Aorun zhaoi (Choiniere et al. 2013; IVPP V15709, Late Jurassic 161mya).

So this multipart study on ‘Pennaraptorans’ is off to several bad starts. Neither ‘Aorun‘, nor ‘Tyrannoraptora’ (see below) are mentioned in the text. Several taxa have been omitted from this clade, including the last common ancestor.

Only two generic taxa and “their last common ancestor (LCA)”
should be enough to define a clade. Look what bad things can happen when you use four suprageneric taxa (Fig. 1). Don’t let in generic taxa that do not belong and omit generic taxa that do belong. Even so, and surprisingly, all taxa employed here are clade members. Unfortunately the clades and a few taxa are a little mixed up due to taxon exclusion.

Figure 1. Cladogram of the Pennaraptora from Pittman and Xu eds. 2020. Color overlays added to show clades in the LRT (Fig. 2).

Figure 1. Cladogram of the Pennaraptora from Pittman and Xu eds. 2020. Color overlays added to show clades in the LRT (Fig. 2).

Foth et al. defined Pennaraptora in 2014.
“Pennaraptora is a clade defined as the most recent common ancestor of Oviraptor philoceratops, Deinonychus antirrhopus, and Passer domesticus (the house sparrow), and all descendants thereof,”  Again, this definition only needs the first two taxa. Passer nests within “all descendants thereof”. Even so, this is a definition we can work with (Fig. 2).

Figure 2. Subset of the LRT focusing on Pennaraptora 2014 = Tyrannoraptora 1999. Here Khaan and Velociraptor substitute for Oviraptor and Deinonychus.

Figure 2. Subset of the LRT focusing on Pennaraptora 2014 = Tyrannoraptora 1999. Here Khaan and Velociraptor substitute for Oviraptor and Deinonychus.

In the LRT ‘Pennaraptora’
is almost a junior synonym of Compsognathidae (Cope 1871; Fig. 2) because two specimens of Compsognathus are basalmost taxa. However, Aorun is the last common ancestor taxon. It was originally considered the oldest known coelurosaurian theropod and a juvenile.

Figure 3. Aorun compared to several other theropods to scale.

Figure 3. Aorun compared to several other theropods to scale.

Figure 4. Aorun skull in situ and slightly restored. This is the basalmost tyrannoraptor.

Figure 4. Aorun skull in situ and slightly restored. This is the basalmost tyrannoraptor in the LRT.

According to Wikipedia, Aorun is now considered a member of
the Tyrannoraptora (Sereno 1999) defined as, “Tyrannosaurus, Passer their last common ancestor [Aorun] and all of its descendants.” So Pennaraptora (2014) is a junior synonym of Tyrannoraptora (1999). The two define the same clade in the LRT and share a last common ancestor.

Coelurosauria (von Huene 1914 is defined as theropods closer to birds than to carnosaurs. In the LRT Tyrannoraptora is also a junior synonym for Coelurosauria.


References
Bidar AL, Demay L and Thomel G 1972b. Compsognathus corallestris,
une nouvelle espèce de dinosaurien théropode du Portlandien de Canjuers (Sud-Est de la France). Annales du Muséum d’Histoire Naturelle de Nice 1:9-40.
Choiniere JN, Clark JM, Forster CM, Norella MA, Eberth DA, Erickson GM, Chu H and Xu X 2013. 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. online. doi:10.1080/14772019.2013.781067
Cope ED 1871. On the homologies of some of the cranial bones of the Reptilia, and on the systematic arrangement of the class. Proceedings of the American Association for the Advancement of Science 19:194-247
Foth C, Tischlinger H and Rauhut OWM 2014. New specimen of Archaeopteryx provides insights into the evolution of pennaceous feathers. Nature. 511 (7507): 79–82.
Huene F v 1914. Über de Zweistämmigkeit der Dinosaurier, mit Beiträgen zer Kenntnis einiger Schädel. Sep.-Abd. Neuen Jahrb. für Mineralogie Beil.-Bd.37:577–589. Pls. vii-xii.
Ostrom JH 1978. The osteology of Compsognathus longipes. Zitteliana 4: 73–118.
Peyer K 2006. A reconsideration of Compsognathus from the upper Tithonian of Canjuers, southeastern France, Journal of Vertebrate Paleontology, 26:4, 879-896.
Pittman M and Xu X eds. 2020.
Pennaraptoran theropod dinosaurs. Past progress and new Frontiers. Bulletin of the American Museum of Natural History 440; 353pp. 58 figures, 46 tables.
Wagner JA 1859. Über einige im lithographischen Schiefer neu aufgefundene Schildkröten und Saurier. Gelehrte Anzeigen der Bayerischen Akademie der Wissenschaften 49: 553.

wiki/Compsognathus
wiki/Tyrannoraptora
wiki/Aorun
wiki/Pennaraptora

Feathers and fangs: What is Hesperornithoides?

Answer:
Hesperornithoides miessleri (Figs. 1, 2; Late Jurassic, Wyoming, USA; Hartman et al. 2019; WYDICE-DML-001 (formerly WDC DML-001)) is the newest fanged anchiornithid theropod dinosaur to be described, compared and nested (Figs. 3, 4).

From the Hartman et al. abstract
“Limb proportions firmly establish Hesperornithoides as occupying a terrestrial, non-volant lifestyle. Our phylogenetic analysis emphasizes extensive taxonomic sampling and robust character construction, recovering the new taxon most parsimoniously as a troodontid close to Daliansaurus, Xixiasaurus, and Sinusonasus.” [see Figure 3, note: Xixiasaurus is not listed in their cladogram].

“All parsimonious results support the hypothesis that each early paravian clade was plesiomorphically flightless, raising the possibility that avian flight originated as late as the Late Jurassic or Early Cretaceous.” [this is an old hypothesis dating back to the discovery of Late Jurassic Archaeopteryx in the 1860s and it remains a well-established paradigm.]

Figure 1. Published reconstruction of Hesperornithes from Hartman et al. 2019, to scale with Caihong, a similar, though smaller, taxon and Sinusonasus, another sister based on very few bones, but look at that canine fang!

Figure 1. Published reconstruction of Hesperornithes from Hartman et al. 2019, to scale with Caihong, a similar, though smaller, taxon preserved with a complete set of bird-like feathers, and Sinusonasus, another sister based on very few bones, but look at that canine fang!

The cladogram by Hartman et al. 2017
(Fig. 3) is similar to one published by Lefevre et al. 2017 in nesting birds (Avialae) as outgroups to the Dromaeosauridae + Troodontidae, the opposite of the large reptile tree (LRT, 1540 taxa, subset Fig. 4).

Today
we’ll compare the Hartman et al. nesting (Fig. 3) to the one recovered by the LRT (Fig. 4).

Figure 2. Tentative restoration of the skull of Hesperornithes alongside to scale skull of Caihong. The maxillae are similar and both have a distinct fang.

Figure 2. Tentative restoration of the skull of Hesperornithes alongside to scale skull of Caihong. The maxillae are similar and both have a distinct fang.

The Hartman et al. cladogram
(Fig. 3) nested Hesperornithoides with Sinusonasus (IVPP V 11527, Xu and Wang 2004; Early Cretacaceous, Fig. 1), as in the LRT (Fig. 4).

The Hartman et al. cladogram included several taxa not previously included in LRT, 1540 taxa, subset Fig. 4), so I added five to the LRT.

  1. Hesperornithoides (Fig. 1) – sister to Sinusonasus in both cladograms
  2. Sinusonasus (Fig. 1) – sister to Hesperornithoides in both cladograms
  3. Daliansaurus (Fig. 5) – nearby outgroup taxon in both cladograms
  4. Alma (Fig. 6) – more distant outgroup taxon in both cladograms
  5. Protarchaeopteryx (Fig. 7) – primitive oviraptorid in both cladograms
Figure 3. Cladogram published by Hartman et al. 2019, colors added to more or less match those in the subset of the LRT (Fig. 4), a distinctly different topology. Here birds and troodontids/anchirornithids are polypheletic.

Figure 3. Cladogram published by Hartman et al. 2019, colors added to more or less match those in the subset of the LRT (Fig. 4), a distinctly different topology. Here birds and troodontids/anchirornithids are polypheletic.

Issues arise in the Hartman et al. cladogram

  1. Birds arise from the proximal outgroup, Oviraptorosauria
  2. Archaeopteryx is not in the lineage of modern and Cretaceous birds
  3. Anchiornithid troodontids are scattered about
  4. Balaur nests with birds
  5. Microraptors and basal tyrannosaurs nest with dromaeosaurids
  6. The outgroup taxon in figure 3 is: Compsognathus; in the SuppData: Dilophosaurus. Neither is a Triassic theropod.
  7. Running the .nex file results in thousands of MPTs (most parsimonious trees), even when pruned down to well-known, largely articulated taxa. Their phylogenetic analysis included 700 characters (and that means hundreds of less-than-complete taxa) tested against 501 taxa. Changing the outgroup taxon to Sinocalliopteryx resulted in far fewer MPTs, but see here for more validated outgroup taxa. Hartman et al. reported, “The analysis resulted in >99999 most parsimonious trees.” Essentially useless… and they knew that attempting to publish their report.
Figure 4. Subset of the LRT focusing on the theropod-bird transition, distinctly different than in Hartman et al. 2019. Here in a fully resolved cladogram, birds and anchiornithids are monophyletic. Taxon inclusion resolves cladistic issues raised by Hartman et al.

Figure 4. Subset of the LRT focusing on the theropod-bird transition, distinctly different than in Hartman et al. 2019. Here in a fully resolved cladogram, birds and anchiornithids are monophyletic. Taxon inclusion resolves cladistic issues raised by Hartman et al.

By contrast,
in the LRT (Fig. 4):

  1. The cladogram is fully resolved (1 MPT).
  2. Birds, including Archaeopteryx and 12 other Solnhofen bird-like taxa arise from anchiornithids, which arise from troodontids (including dromaeosaurids), which arise from Ornitholestes and kin, which arise from the CNJ79 specimen attributed to Compsognathus and kin (including therzinosaurs + oviraptorids), which arises from the holotype Compsognathus and kin (including ornithomimosaurs and tyrannosaurs).
  3. Double killler-clawed Balaur nests with Velociraptor, not with birds.
  4. The outgroup taxa in the LRT include the Triassic dinosaurs, Herrerasaurus, Tawa and a long list going back to Silurian jawless fish.
  5. Hesperornithoides (Fig. 1) and Sinusonasus (Fig. 1) nest with another anchiornithid with fewer teeth and one elongated canine, Caihong (Fig. 1) and a long list of other shared traits. Caihong has a full set of bird-like feathers, so less well-preserved Hesperornithoides likely shared this trait. Caihong nests closer to Archaeopteryx in the Hartman et al. cladogram.
Figure 6. Daliansaurus reconstructed from the original tracing.

Figure 5. Daliansaurus reconstructed from the original tracing. In the Hartman et al. cladogram, this taxon nests close to Hesperornithoides. In the LRT it nests at the base of the Hesperornithes clade.

A few suggestions for Hartman et al. 2019

  1. Build your tree with fewer, but more complete taxa in order to achieve full resolution
  2. Choose a plesiomorphic Triassic theropod or dinosaur outgroup for your outgroup
  3. Practice more precision in your reconstructions. Do not freehand anything. Do not add bones where bones are not known.
  4. Try not to borrow cladograms (like the TWiG dataset) from others, but build your own, especially when the results are so demonstrably poor (>99,999 MPTs)
  5. Include both Compsognathus specimens. They are different from one another and, apparently, key to understanding interrelationships.
  6. Include as many of the 13 Solnhofen birds and pre-birds that you can and show reconstructions so we know you understand the materials. Checking individual scores is like going to Indiana Jones’ government warehouse. Note how the Solnhofen birds split apart and nest at the bases of all the derived bird clades in the LRT (Fig. 4).
FIgure 5. Alma reconstructed and restored (gray).

FIgure 6. Alma reconstructed and restored (gray).

Hartman et al. report, 
“We follow the advice of Jenner (2004) that authors should attempt to include all previously proposed characters and terminal taxa, while explicitly justifying omissions. To this end we have attempted to include every character from all TWiG papers published through 2012, with the goal to continually add characters.”

As their results demonstrate, such efforts are a waste of time.
Pertinent taxa and suitable outgroup taxa were overlooked. The goal is full resolution and understanding. If incomplete taxa and too many characters prevent you from reaching this goal, start pruning, or start digging into the data. There is only one tree topology in Deep Time. Our job is to find it.

Figure 9. Protarchaeopteryx traced in situ, reconstructed a bit and the skull of Incisivosaurus for comparison.

Figure 7. Protarchaeopteryx traced in situ, reconstructed a bit and the skull of Incisivosaurus for comparison. This taxon nests with oviraptorids in both cladograms, basal to Archaeopteryx and birds in Hartman et al. 2019. Not sure if that is all the tail there is, or if more is buried or missing. Probably the latter, according to phylogenetic bracketing.

I sincerely hope this review of Hartman et al. 2019
is helpful. The LRT confirms their nesting of Hesperornithoides with Sinusonasus. Outside of that the two cladograms diverge radically and only one of these two competing cladograms is fully resolved with a gradual accumulation of traits at every node.

The above video tour of the Wyoming Dinosaur Center in Thermopolis
from Wyoming PBS spends a fair amount of time with Hesperornithoides. The conclusions mentioned by the various narrators are not supported by the LRT.


References
Hartman S, Mortimer M, Wahl WR, Lomax DR, Lippincott J and Lovelace DM 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
Lefèvre U, Cau A, Cincotta A,  Hu D-Y, Chinsamy A,Escuillié F and Godefroit P 2017. A new Jurassic theropod from China documents a transitional step in the macrostructure of feathers. The Science of Nature, 104: 74 (advance online publication). doi:10.1007/s00114-017-1496-y
Xu X and Wang X-l 2004. A New Troodontid (Theropoda: Troodontidae) from the Lower Cretaceous Yixian Formation of Western Liaoning, China”. Acta Geologica Sinica 78(1): 22-26.

wiki/Sinusonasus
wiki/Troodontidae
wiki/Hesperornithoides
wiki/Xixiasaurus
wiki/Anchiornthidae
wiki/Origin_of_birds

New view on ‘Paravians’: Agnolin et al. 2019

Agnolin et al. 2019 produced
a new view of early bird and pre-bird relationships. They write, “We here present a review of the taxonomic composition and main anatomical characteristics of those theropod families closely related with early birds, with the aim of analyzing and discussing the main competing hypotheses pertaining to avian origins. We reject the postulated troodontid affinities of anchiornithines, and the dromaeosaurid affinities of microraptorians and unenlagiids, and instead place these groups as successive sister taxa to Avialae.”

By contrast
in the large reptile tree (LRT, 1401 taxa; subset Fig. 1) some troodontids are basal to anchiornithines, which are basal to avians. Other traditional troodontids are not basal to birds and pre-birds.

Agnolin et al. report, “Regarding character evolution, we found that: (1) the presence of an ossified sternum goes hand in hand with that of ossified uncinate processes; (2) the presence of foldable forelimbs in basal archosaurs indicates widespread distribution of this trait among reptiles, contradicting previous proposals that forelimb folding driven by propatagial and associated tendons was exclusive to the avian lineage; (3) in basal paravians and avialans (e.g., Archaeopteryx, Anchiornis) the wings are relatively large and wide, with relatively short rectricial feathers, a rounded alar contour, and a convex leading margin. These taxa exhibit restricted forelimb folding capability with respect to more derived birds, their hands being preserved at angles of flexion (with respect to the radius/ulna) of no less than 90. In more derived birds, however, the rectrices are notably elongate and the angle between the hand and forearm is much less than 90, indicating not only increased forelimb folding capability but also an increased variety of wingbeat movements during flight. Because of the strong similarities in pectoral girdle configuration between ratites and basal avialans and paravians, it is possible to infer that the main forelimb movements were similar in all these taxa, lacking the complex dorsoventral wing excursion characteristic of living neognathans.”

Unfortunately
Agnolin et al. presented a cladogram that was largely unresolved. According to the LRT that loss of resolution can be attributed to one thing: exclusion of taxa. Key taxa missing from the Agnolin et al. tree include:

  1. Compsognathus (both species)
  2. Ornitholestes
  3. The other ten or so ‘Archaeopteryx’ specimens

With the addition of these key taxa theropods (including pre-birds and birds) become completely resolved in the LRT (subset Fig. 1).

Figure 1. More taxa, updated tree, new clade names.

Figure 1. More taxa, updated tree, new clade names, from an earlier blog post.

References
Agnolin FL et al. (4 co-authors) 2019. Paravian phylogeny and the dinosaur-bird transition: an overview. Frontiers in Earth Science 6:252.
doi: 10.3389/feart.2018.00252

Dr J Gauthier lecture video on birds + dinos

If you watch this…
Stay for the brilliant question and answer period at the end.

And…
returning to an earlier subject…
Geologist Randall Carlson reports on Joe Rogan Experience #606 (1:35:44) —  “See, here’s the thing. Modern science does tend to get over specialized. And so what happens is, they guy looking at extinctions might not be looking at glacial melting. The guy looking at glacial melting… the geologist is not looking at what’s going on in the sky. They’re not looking at traditions, you know, traditions from thousands of years ago. What it does is, because of the powerful of this specialization, this specialization is extremely powerful, but the thing of it is… it’s easy to miss the big picture. What that does is, it opens the door for generalists, guys who are just, people who are just, men or women, anybody who is curious about this stuff, look into it and try to see the big picture.”

In other words…
taxon exclusion problems can be solved by a wide gamut analysis of the entire range of tetrapods now known.

Joe Rogan says (1:37:46),
“People love to be able to dismiss anything that’s not mainstream, right?” To which Randall Carlson replies, “Because there’s this cult of authority.” Randall Carlson continues (1:38:40) “They’ve got this idea in their mind that there’s this authority that’s got it all explained, which makes it easy, because if somebody’s got this all explained, then we don’t need to concern ourselves with it or think about it. Right? So, what I see is, ‘Okay… forget about who says what. Look at the facts. Let the facts dictate to us what the meaning of all this is. And let’s look at all points of view.” 

The idea that a meteor impact ended the last Ice Age,
and killed the northern megafauna first proposed by Randall Carlson and others gained new hard evidence with the recent discovery of a Paris-sized crater on the north rim of Greenland. Details and videos here: https://earthsky.org/earth/meteorite-crater-under-greenland-ice

Let’s talk about the pygostyle in birds

…because Wang and O’Connor 2017 just wrote a paper on pygostyle evolution.

From their abstract: “The transformation from a long reptilian tail to a shortened tail ending in a pygostyle and accompanied by aerodynamic fanning rectrices is one of the most remarkable adaptations of early avian evolution. All birds with a pygostyle form a monophyletic clade, the Pygostylia (Chiappe, 2002), which excludes only the long bony-tailed birds, Archaeopteryx and the Jeholornithiformes (Jeholornis and kin).”

Key thought from their abstract: “There further exist distinct differences in pygostyle morphology between Sapeornithiformes, Confuciusornithiformes, Enantiornithes, and Ornithuromorpha.”

Figure 1. Flawed theropod cladogram according to Wang and O'Connor 2017 based on Brusatte 2014.

Figure 1. Flawed theropod cladogram according to Wang and O’Connor 2017 based on Brusatte 2014. This cladogram suffers from taxon exclusion and so tells us little about pygostyle evolution.  Only one clade here has a pygostyle. See figure 2 for more data.

Wikipedia reports, “The pygosylians fall into two distinct groups with regard to the pygostyle. The Ornithothoraces have a ploughshare-shaped pygostyle, while the more primitive members had longer, rod-shaped pygostyles. The earliest known member of the group is the enantiornithine species Protopteryx fengningensis, from the Sichakou Member of the Huajiying Formationof China, which dates to around 131 Ma ago,”

Figure 2. Subset of the LRT focusing on derived theropods. Those with a pygostyle are colored.

Figure 2. Subset of the LRT focusing on derived theropods. Those with a pygostyle are colored. Among birds, gray taxa have a distal fusion, as do other very derived non-bird taxa, some of which are not included here. Wnag and O’Connor apparently did not test several Solnhofen birds and so did not understand the basal division of bird clades that occurred  among the ‘Solnhofen birds’  shown here.

 

Wang and O’Connor correctly note
that some derived therizinosaurs and ovitrapotorsaurs have distal caudal vertebrae that are fused after a long string of unfused verts. Not correctly they consider this the first of many evolutionary steps toward the completely fused pygostyle of extant birds. A subset of the large reptile tree (LRT, figure 2) documents three origins for the pygostyle in Avialan taxa and a few other aborted attempts in other clades.

If only Wang and O’Connor
had used a half-dozen Solnhofen birds (they can’t ALL be Archaeopteryx) in their study they would have found the multiple convergent evolution of the pygostyle in basal Aves. Once again, taxon exclusion is keeping the blinders on paleontologists.

Wang and O’Connor do not recover
Sapeornis as a basal Ornithourmorph. The write: “Despite published diversity, the Sapeornithiformes is considered a monospecific clade with all taxa referable to Sapeornis chaoyangensis.

Wang and O’Connor were very interested in
Caudipteryx, traditionally considered a basal member of the Oviraptorosauria. It now nests with Limusaurus, or closer yet, the ‘juvenile’ Limusaurus, a sister to the oviraptorid, Khaan. It lacks a pygostyle, but has a fan of tail feathers.

Wang and O’Connor conclude “Fusion or partial fusion of the terminal caudal vertebrae in maniraptorans is observed in the Therizinosauroidea, Oviraptorosauria and potentially also the Scansoriopterygidae. However, morphological differences between these phylogenetically separated taxa indicate these co-ossified structures cannot be considered equivalent to the avian pygostyle. Outside the Ornithuromorpha, no group preserves evidence of a tail complex.”

Scatter diagrams of pygostyle traits provided by Wang and O’Connor
(their figure 7) also show four clades of rarely and then barely overlapping data. The vast majority is non-overlapping data as the pygostyle really did evolve several times within Aves.

Notably the bird mimics
Microraptor and Sinornithosaurus, both closer to T-rex and Orinitholestes than to birds, have no trace of a pygostyle.

References
Chiappe LM 2002. Basal bird phylogeny: problems and solutions. In: Chiappe L M, Witmer L eds. Mesozoic Birds: Above the Heads of Dinosaurs. Berkeley: University of California Press. 448–472.
Wang W and O’Connor JK 2017. Morphological coevolution of the pygostyle and tail feathers in Early Cretaceous birds. Vertebrata PalAsiatica 2017:10: 55:3: 1-26.

wiki/Pygostylia

Deinocheirus: a giant ornithomimosaur

Updated January 28, 2020
with a new comparison to the ornithomimosaur, Gallimiumus, distinct from Struthiomimus.

Following a long list of blog posts
that reported an inability of the large reptile tree, to nest various theropods in their traditional nodes, today Deinocheirus (Fig. 1) nests with ornithomimosaurs, like Gallimimus,  despite not having a pinched mt3 and having a pedal digit 1.

Figure 1. The skull of Deinocheirus. Note how the mandible does not completely close cranially when the anterior tips touch. I wonder if this was a sieving organ lined with baleen-like structures? That hypothesis goes with the very deep mandible and the equal lengths of both upper and lower jaws.

Figure 1. The skull of Deinocheirus. Note how the mandible does not completely close cranially when the anterior tips touch. I wonder if this was a sieving organ lined with baleen-like structures? That hypothesis goes with the very deep mandible and the equal lengths of both upper and lower jaws.

Previous studies
assumed that Deinocheirus was an ornithomimosaur, because it had very similar manus and forelimb proportions. When the skull was discovered, it was likewise toothless.

Figure 2. Deinocheirus specimens and a composite illustration.

Figure 2. Deinocheirus specimens and a composite illustration.

Deinocheirus mirificus (Osmólska & Roniewicz, 1970, Latest Cretaceous, 70 mya 11m) was originally and later considered a giant and basal ornithomimosaur. The large reptile tree nests Deinocheirus with Gallimimus.


References
Lee YN, Barsbold R, Currie PJ, Kobayashi Y, Lee HJ, Godefroit P, Escuillié F and Chinzorig T 2014. Resolving the long-standing enigmas of a giant ornithomimosaur Deinocheirus mirificus. Nature 515 (7526): 257–260.
Osmólska H and Roniewicz E 1970. Deinocheiridae, a new family of theropod dinosaurs. Palaeontologica Polonica. 21:5-19.

wiki/Deinocheirus

 

 

Another look at Microraptor

As reported earlier
the theropod community is not happy with the large reptile tree nesting of Yutyrannus with Allosaurus (see discussion yesterday). Today we’ll look at the heretical (non-traditional) nesting of Microraptor with Compsognathus (Fig. 1).

The traditional nesting of Microraptor
is with other ‘raptors’, like Velociraptor (Fig. 1). By contrast, the large reptile tree nested Microraptor between Compsognathus and Sinornithosaurus, and not far from Tianyuraptor at the base of the Tyrannosaurus clade.

Figure 3. Provisional sisters to Microraptor (middle) now include Compsognathus (above) and Velociraptor (below). Which ones appears to share more traits with Microraptor?

Figure 3. Provisional sisters to Microraptor (middle) now include Compsognathus (above) and Velociraptor (below). Which ones appears to share more traits with Microraptor?

 

Figure 2. Skull of Microraptor (color, middle) compared to Compsognathus (above) and Velociraptor (below). The two skulls that resemble each other more are more closely related.

Figure 2. Skull of Microraptor (color, middle) compared to Compsognathus (above) and Velociraptor (below). The two skulls that resemble each other more are more closely related.

The following traits
are shared between Microraptor with Compsognathus to the exclusion of Velociraptor in the large reptile tree, a study that includes a wide gamut of reptiles, not just theropods.

  1. lacrimal not deeper than maxilla
  2. narial opening dorsolaterally
  3. naris at snout tip, not elevated
  4. frontal separated from upper temporal fenestra
  5. posterior parietal 20-40º
  6. jaw joint descends
  7. caudal transverse processes present beyond eighth caudal
  8. Mc2-3 align at or beyond m1.2
  9. Mt2-3 align with p1.1

Of course
there is also a list of traits shared between Compsognathus and Velociraptor to the exclusion of Microraptor. And indeed there is also a list of traits linking Microraptor to Velociraptor to the exclusion of Compsognathus. 

Look at that face!
If you had to lump and split Compsognathus, Microraptor and Velociraptor based just on the skull alone (Fig. 2), which two would you lump together?

Feathers
The presences of extensive feathers on all four limbs of Microraptor — not in the direct ancestry of extant birds — points to a possible convergent evolution in this clade… OR more extensive (bit not preserved) feathers in a last common ancestor, like Compsognathus.

The presence of only protofeathers
in the contemporaneous Sinosauropteryx indicates a likely reduction in plumage in that short-legged taxon, slightly off the main line of bird evolution represented by Archaeopteryx of the Late Jurassic. Previously (Ji and Ji 1996) Sinosauropteryx was considered the basalmost taxon with the basalmost protofeathers. Not so both chronologically and phylogenetically.

Figure 2. Sinosauropteryx fossil.

Figure 3. Sinosauropteryx fossil. Apparently the presence of simple feathers here is derived from or a reversal of more primitive taxa with more extensive, more derived feathers according to its place on the large reptile tree. This dinosaur appears to be the Early Cretaceous analog to our extant squirrels in its niche and appearance.

 

References
Ji Q and Ji S-A 1996. On the Discovery of the earliest fossil bird in China (Sinosauropteryxgen. nov.) and the origin of birds. Chinese Geology 233:30-33.
Ostrom JH 1978. The osteology of Compsognathus longipes. Zitteliana 4: 73–118.
Osborn HF 1905. Tyrannosaurus and other Cretaceous carnivorous dinosaurs. Bulletin of the AMNH (New York City: American Museum of Natural History) 21 (14): 259–265.
Osborn HF 1924. Three new Theropoda, Protoceratops zone, central Mongolia”. American Museum Novitates 144: 1–12.
Ostrom JH 1970. Stratigraphy and paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin area, Wyoming and Montana. Bulletin of the Peabody Museum of Natural History 35: 1–234.
Wagner JA 1859. Über einige im lithographischen Schiefer neu aufgefundene Schildkröten und Saurier. Gelehrte Anzeigen der Bayerischen Akademie der Wissenschaften 49: 553.
Xing L, Persons WS, Bell PR, Xu X, Zhang J-P, Miyashita T, Wang F-P and Currie P 2013. Piscivery iin the feathered dinosaur Microraptor. Evolution 67(8):2441-2445.
Xu X, Zhou Z, Wang X, Kuang X, Zhang F and Du X 2003. Four-winged dinosaurs from China. Nature, 421: 335–340.

wiki/Tyrannosaurus
wiki/Compsognathus
wiki/Microraptor
wiki/Velociraptor
wiki/Sinosauropteryx

Microraptor: not a ‘raptor’??

Earlier
the large reptile tree nested two putative dromaeosaurs with composgnathid/tyrannosaurs, Tianyuraptor and Zhenyuanlong. Today the famous four-wiinged dinosaur/bird Microraptor (Figs. 1, 2) is added to that list, nesting between Compsognathus and Tianyuraptor, all three basal to T-rex.

Figure 1. Microraptor gui (IVPP V 13352) shown in two photos and with DGS tracing of bones and feathers.

Figure 1. Microraptor gui (IVPP V 13352) shown in two photos and with DGS tracing of bones and feathers. Click to enlarge.

This is the specimen
that inspired a PBS Nova special and a race between competing teams of paleontologists to figure out the best usage for the odd foot feathers. The Kansas team led by Dr. Larry Martin produced a sprawling model that went against everything we know di dinosaur hind limbs.

Figure 2. Microraptor gui (IVPP V 13352) reconstructed from tracings in figure 1. There are no surprises here, except a provisional closer relationship with Compsognathus than with Velociraptor. Microraptor has a large pedal claw two, but it is not quite the killing claw seen in droamaeosaurs.

Figure 2. Microraptor gui (IVPP V 13352) reconstructed from tracings in figure 1. There are no surprises here, except a provisional closer relationship with Compsognathus than with Velociraptor. Microraptor has a large pedal claw two, but it is not quite the killing claw seen in droamaeosaurs.

So this makes three former dromaeosaurs
now nesting with long-legged Compsognathus and Tyrannosaurus. Among them, only Microraptor has long arms/wings. Zhenyuanlong has equally substantial feathers. So this adds credulity to the idea that Compsognathus was well feathered. Only Microraptor has a posteriorly directed pubic foot, but see Compsognathus (Fig. 4) for its derivation. This is not a posteriorly directed pubis.

Figure 4. Compsognathus was not preserved with feathers, but with a sister taxon like Microraptor, it might have had substantial feathers.

Figure 4. Compsognathus was not preserved with feathers, but with a sister taxon like Microraptor, it might have had substantial feathers.

Is Microraptor a bird (clade Aves)?
Wikipedia (Evolution of Birds) defined Aves as “all descendants of the most recent common ancestor of a specific modern bird species (such as the house sparrow, Passer domesticus), and either Archaeopteryx, or some prehistoric species closer to Neornithes (to avoid the problems caused by the unclear relationships of Archaeopteryx to other theropods).[ If the latter classification is used then the larger group is termed Avialae. Currently, the relationship between dinosaurs, Archaeopteryx, and modern birds is still under debate.”

Is Microraptor a member of the clade Avialae?
Wikipedia defines the clade Avialae “a clade of dinosaurs containing their only living representatives, the birds. It is usually defined as all theropod dinosaurs more closely related to modern birds (Aves) than to deinonychosaurs, though alternate definitions are occasionally used (see below).” 

So, Microraptor is not a bird. 
In the same light, not all Archaeopteryx specimens are birds, but Wellnhoferia (aka The Solnhofen specimen, Archaeopteryx grandis) apparently is a bird as it nests closest to living birds of all Solnhofen specimens.

Yes
I don’t have a complete list of theropods in the large reptile tree. But this is what the tree recovers at present. If valid, theropods with long feathers on their forelimbs appear earlier than some workers think. And maybe I’m just catching up to the rest of them.

There are other specimens out there referred to Microraptor
and I have not tested them yet. Perhaps one or more are more closely related to Velociraptor. 

Addendum
Here is the skull of the QM V 1002 specimen of Microraptor (Fig. 5, Xing et al. 2013). The two nest together in the large reptile tree, but differ in several traits. They are not conspecific.

Figure 5. The skull of another Microraptor, QM V1002. The two nest together in the large reptile tree.

Figure 5. The skull of another Microraptor, QM V1002, the fish eater. The two nest together in the large reptile tree. I’m a little confused by the occiput. I’ll get back to that later.

References
Xing L, Persons WS, Bell PR, Xu X, Zhang J-P, Miyashita T, Wang F-P and Currie P 2013. Piscivery iin the feathered dinosaur Microraptor. Evolution 67(8):2441-2445.
Xu X, Zhou Z, Wang X, Kuang X, Zhang F, and Du X 2003. Four-winged dinosaurs from China. Nature, 421: 335–340.

wiki/Microraptor

 

 

Zhenyuanlong: Dromaeosaur? No. Tyrannosaur with wings? Yes.

Lü and Brusatte 2015
described a short-armed, winged Early Cretaceous Liaoning theropod, Zhenyuanlong suni (Fig. 1, JPM-0008 Jinzhou Paleontological Museum), as a dromaeosaur. Their published phylogenetic analysis included only dromaeosaurs but their text indicates a large inclusion set.

Figure 1. Zhenyuanlong in situ with colors applied to bones and feathers. These colors are transferred to create the reconstruction in figure 3.

Figure 1. Zhenyuanlong in situ with colors applied to bones and feathers. These colors are transferred to create the reconstruction in figure 3. The pelvic elements are reconstructed at right. The manus and pes are reconstructed at left.  Scale bars are 10cm.

From the Lü and Brusatte text
“We included Zhenyuanlong in the phylogenetic dataset of Han et al., based on the earlier analysis of Turner et al, which is one of the latest versions of the Theropod Working Group dataset. This analysis includes 116 taxa (two outgroups, 114 ingroup coelurosaurs) scored for 474 active phenotypic characters. Following Han et al., characters 6, 50, and 52 in the full dataset were excluded, 50 multistates were treated as ordered, and Unenlagia was included as a single genus-level OTU. The analysis was conducted in TNT v1.142 with Allosaurus as the outgroup.”

I reconstructed this theropod,
from published photographs (Figs. 1, 2) using (DGS digital graphic segregation), added it to the large reptile tree and found that it nested between tiny Compsognathus and gigantic Tyrannosaurus rex. Of course, Zhenyuanlong had the opportunity to nest with several dromaeosaurs, but it did not do so.

Figure 2. Skull of Zhenyuanlong in situ, as originally traced, colorized with skull, palate and mandible segregated.

Figure 2. Skull of Zhenyuanlong in situ, as originally traced, colorized with skull, palate and mandible segregated. Original quadrate may be a quadratojugal.

When you look at the reconstruction,
(Fig. 3) the similarity to T. rex becomes immediately apparent… except for those long feathered wings, of course.

I’ll run through several of the traits that link
Zhenyuanlong to Tyrannosaurus to the exclusion of dromaeosaurs here. It’s a pretty long list. Even so, if you see any traits that should not be listed, let me know and why.

  1. skull not < cervical series length
  2. skull not < half the presacral length
  3. premaxilla oriented up
  4. lacrimal not deeper than maxilla
  5. naris dorsolateral
  6. naris at snout tip, not displaced dorsally
  7. orbit length < postorbital skull
  8. orbit not > antorbital fenestra
  9. orbit no > lateral temporal fenestra
  10. orbit taller than wide
  11. frontal with posterior processes
  12. posterior parietal inverted ‘B’ shape
  13. jugal posterior process not < anterior
  14. parietal strongly constricted
  15. quadratojugal right angle
  16. majority of quadrate covered by qj and sq
  17. postorbital extends to minimum parietal rim
  18. maxillary teeth at least 2x longer than wide
  19. mandible tip rises
  20. angular not a third of mandible depth
  21. retroarticular process expands dorsally and ventrally
  22. cervicals taller than long
  23. cervicals decrease cranially
  24. mid cervical length < mid dorsal
  25. caudal transverse processes present beyond the 8th caudal
  26. humerus/femur ratio < 0.55
  27. metacarpals 2 & 3 do not align with manual one joints
  28. pubis angles ventrally – not posteriorly
  29. 4th trochanter of femur sharp
  30. metatarsals 2 & 3 align with p1.1
Figure 3. Zhenyuanlong reconstructed in lateral view. Something behind the pelvis could be the remains of an egg, but needs further study. Both sets of wing feathers are superimposed here. Click to enlarge.

Figure 3. Zhenyuanlong reconstructed in lateral view. Something behind the pelvis could be the remains of an egg, but needs further study. Both sets of wing feathers are superimposed here. Click to enlarge. Note the pubis is not oriented posteriorly. Note the longer legs of Zhenyuanlong compared to tested dromaeosaurs.

Shifting
Zhenyuanlong to the dromaeosaurs adds a minimum of 127 steps to the large reptile tree. There is one clade of theropods that nests between the current tyrannosaur and dromaeosaur clades.

Figure 3. Cladogram subset of the large reptile tree showing the strong nesting of Zhenyuanlong as the current sister to Tyrannosaurus. Obviously many more theropod taxa are missing here. They have not been tested yet.

Figure 4. Cladogram subset of the large reptile tree showing the strong nesting of Zhenyuanlong as the current sister to Tyrannosaurus. Obviously many more theropod taxa are missing here. They have not been tested yet.

Note
I have not tested as many theropods as there are in several theropod cladograms.

The possible faults with the Lü and Brusatte study were

  1. a lack of reconstructions to work with, rather than just a score sheet that others had created and they trusted. Reconstructions test identifications by making sure the puzzle pieces actually fit, both morphologically and cladisitically.
  2. I think they were fooled by the apparent posterior orientation of the pubis in situ when in vivo it was not oriented posteriorly
  3. I’m guessing that the traits they used could be used on in situ fossils without making reconstructions. The traits I use require reconstructions.
Figure 0. Taxa ancestral to tyrannosaurs beginning with the CNJ7 specimen of Compsognathus.

Figure 0. Taxa ancestral to tyrannosaurs beginning with the CNJ7 specimen of Compsognathus.

With this nesting
the origin of long pennaceous wing feathers is evidently more primitive than earlier considered, developed twice. And perhaps this is why T. rex had such tiny arms. They were former wings, not grasping appendages.

References
Lü J and Brusatte SL 2015. A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution. Scientific Reports 5, 11775; doi: 10.1038/srep11775.