Asteriornis: Oldest crown bird fossil yet discovered? No.

Updated May 19, 2021
with a revised reconstruction of Asteriornis, and the addition of a close relative, the giant flightless goose, Cnemiornis. Click here to see the update.

Taxon exclusion
is the problem here. Still, it’s a wonderful and rare 3D bird fossil.

Figure 1. Asteriornis, a 3D bird fossil from the Latest Cretaceous, now nests with Cnemiornis, a giant flightless goose, in the LRT.
Figure 1. Asteriornis, a 3D bird fossil from the Latest Cretaceous, now nests with Cnemiornis, a giant flightless goose, in the LRT.

Writing in Nature, Field et al. 2020
bring us a new latest Cretaceous bird, Asteriornis (Fig. 1).The authors report, “The fossil represents one of the only well-supported crown birds from the Mesozoic era, and is the first Mesozoic crown bird with well-represented cranial remains.The fossil is between 66.8 and 66.7 million years old—making it the oldest unambiguous crown bird fossil yet discovered.”

The authors note,
“The general appearance of the premaxillary beak resembles that of extant Galliformes, particularly in its gently down-curved tip and delicate construction, with no ossified joints among the rostral components.”

Figure 2. Cnemiornis skull in three views. Compare to latest Cretaceous Asteriornis in figure 3.
Figure 2. Cnemiornis skull in three views. Compare to latest Cretaceous Asteriornis in figure 3.

Among crown birds, (Neornithes)
Asteriornis is old (66 mya), but the hen-sized ostrich sister, Patagopteryx, is older (80 mya), more primitive and was descried earlier (Alvarenga and Bonaparte 1992). Later Chiappe (1996, 2002, 2015) nested Patagopteryx between Enantiornithes and Hesperonis. Patagopteryx was not tested by Field et al. Instead the authors report, “The Mesozoic record of well-supported crown birds is restricted to a single latest Maastrichtian taxon, Vegavis iaai.” In the large reptile tree (LRT, 1657+ taxa then 1861 taxa now; subset Fig. 4), gracile, long-legged Vegavis lies just outside the clade of Crown birds.

Figure 1. The two-toed ostrich (Struthio) nests with the four-toed Patagopteryx, when all relatives have only three toes.
Figure 3. The two-toed ostrich (Struthio) nests with the four-toed Patagopteryx, when all relatives have only three toes.

Field et al. nested Asteriornis 
uncertainly either closer to geese (Anseriformes) or closer to chickens (Galliformes), or at the base of the traditional, but invalid clade, ‘Galloanserae’. The authors report, “The specimen exhibits a previously unseen combination of features that are diagnostic of Galliformes and Anseriformes, which together form the crown clade Galloanserae—one of the most deeply diverging clades of crown birds and the sister group to the hyperdiverse extant clade Neoaves.”

The LRT agrees. The Galliformes do not nest with the Anseriformes.

Figure x. Subset of the LRT focusing on theropods. Asteriornis now nests with Cnemiornis, the giant flightless goose.
Figure 4. Subset of the LRT focusing on theropods. Asteriornis now nests with Cnemiornis, the giant flightless goose.

Chickens and ducks are not related to one another
in LRT (subset, Fig. 4). Chickens are related to grouse, peacocks, sparrows, hoatzins, parrots and other ground-dwelling seed eaters. Ducks and geese arise from long-legged Presybyornis and other long-legged shorebirds. In the LRT, Asteriornis is closer to the newly added giant, flightless goose, Cnemiornis.

Field et al. have too few taxa
in their taxon list. Only one Archaeopteryx is shown in their cladogram, but it was not tested in their analysis where Hesperornithes and Ichthyornis are outgroup taxa. By contrast, in the LRT, both of these toothy taxa are members of the crown group, nesting between toothless ratites and all other toothless birds. Neither the chicken clade nor the duck clade are basal clades in the LRT.

Dr. Kevin Padian (2020) wrote a companion article
explaining the importance of Asteriornis and its relationship to crown birds and stem birds for a broader audience. Padian reports, “Ancient birds are outside the crown group because they lack the structural and physiological features characteristic of living birds. Sometime during the latest Cretaceous, a stem-group lineage of birds evolved that had much higher growth rates than these more basal lineages, and that generally matured within a year or even sooner. These became the crown-group birds.”

Given Dr. Padian’s definitions
several Cretaceous birds, including toothed forms (Fig. 4), qualify as crown group birds because they phylogenetically appear in the LRT after the basalmost extant bird, the kiwi (Apteryx). It only takes one primitive, but extant taxon to define a crown clade.

Dr. Padian also reviews the disagreement
between molecular evidence and the new palaeontological evidence offered by Asteriornis. He reports, “The evidence for Asteriornis reported by Field and colleagues implies that crown-group birds first evolved when the Cretaceous period was nearly over.” That’s not true for many reasons, all based on taxon exclusion.

Field et al. considered Asteriornis unique among known taxa
in exhibiting caudally pointed nasals that overlie the frontals and meet at the midline, and a slightly rounded, unhooked tip of the premaxilla. That first trait appears to be an error. The frontals extend to the premaxilla in Asteriornis. The mesethmoid, the same ‘soft spot’ that creates the casque in Casuarius, the cassowary, may be the source of the confusion.


References
Alvarenga and Bonaparte 1992. A new flightless land bird from the Cretaceous of Patagonia; pp. 51–64 in K. E. Campbell (ed.), Papers in Avian Paleontology, Honoring Pierce Brodkorb. Natural History Museum of Los Angeles County, Science Series 36.
Chiappe LM 1996a. Late Cretaceous birds of southern South America: anatomy and systematics of Enantiornithes and Patagopteryx deferrariisi; pp. 203–244 in G. Arratia (ed.), Contributions of Southern South America to Vertebrate Paleontology, Münchner Geowissenschaftliche Abhandlungen Volume 30.
Chiappe LM 1996. 
Early avian evolution in the southern hemisphere: Fossil record of birds in the Mesozoic of Gondwana. Memoirs of the Queensland Museum 39:533–556.
Chiappe LM 2002. Osteology of the flightless Patagopteryx deferrariisi from the late Cretaceous of Patagonia (Argentina) pp.281–316 in Mesozoic Birds, Above the Heads of Dinosaurs, Chapter: 13, Editors: Chiappe LM and Witmer LM, University of California Press.
Field DJ, Benito J, Chen A, Jagt JWM and Ksepka DT 2020. Late Cretaceous neornithine from Europe illuminates the origins of crown birds. Nature 579:397–401.
Padian K 2020. Poultry through time. Nature online

Taxon list used by Field et al. 2020.
Ichthyornis_dispar
Tinamus_robustus
Vegavis_iaai
Chauna_torquata
Anhima_cornuta
Wilaru_tedfordi
Presbyornis_pervetus
Conflicto_antarcticus
Anatalavis_oxfordi
Anseranas_semipalmata
Dendrocygna_eytoni
Cereopsis_novaehollandiae
Anser_caerulescens
Tadorna_tadornoides
Leipoa_ocellata
Megapodius_reinwardt
Megapodius_eremita
Alectura_lathami
Macrocephalon_maleo
Gallus_gallus
Phasianus_colchicus
Coturnix_pectoralis
Acryllium_vulturinum
Crax_rubra
Ortalis_vetula
Dromaius_novaehollandiae
Dinornis_robustus
Struthio_camelus
Lithornis_promiscuus
Lithornis_plebius
Paracathartes_howardae
Burhinus_grallarius
Porphyrio_melanotus
Antigone_rubicunda
Cariama_cristata
Asteriornis_maastrichtensis
Gallinuloides_wyomingensis
Pelagornis_chilensis
Protodontopteryx_ruthae

Oculudentavis: not a tiny bird or dinosaur. It’s a tiny cosesaur lepidosaur.

Figure 1. Oculudentavis in amber much enlarged. See figure 2 for actual size.

Figure 1. Oculudentavis in amber much enlarged from Xing et al. 2020. See figure 2 for actual size.

I never thought the tiny Middle Triassic pterosaur ancestor, Cosesaurus
(Fig. 2, 4) would ever be joined by an Early Cretaceous sister taxon that was even smaller. Yesterday the impossible happened when the editors of Nature published a description of tiny Oculudentavis (Xing et al. 2020; Figs. 1, 2; Early Cretaceous, 99 mya; 1.4cm skull), which the authors mistakenly considered a basal bird with teeth and the smallest Mesozoic dinosaur.

Figure 2. CT scans of Oculudentavis from Xing et al. 2020 and colored here, plus a comparison of Cosesaurus to scale.

Figure 2. CT scans of Oculudentavis from Xing et al. 2020 and colored here, plus a comparison of Cosesaurus to scale.

Taxon exclusion
Unfortunately the authors did not test Oculudentavis with Cosesaurus, a fenestrasaur, tritosaur lepidosaur… a taxon far from dinosaurs. When Oculudentavis was added to the large reptile tree (LRT) as the 1656th taxon, the tree length was 20291.

As a test
I forced Oculudentavis over to the London specimen of Archaeopteryx, which Xing et al. recovered as a sister, and the LRT bumped up to 20324, a mere 33 steps more despite the huge phylogenetic distance.

I’ve said it before,
convergence is rampant in the tetrapod family tree.

To that point, it should be remembered,
the original describers of Cosesaurus (Ellenberger and de Villalta 1974) mistakenly considered it a Middle Triassic stem bird.

In contrast,
Peters (2000) recovered Cosesaurus and kin with pterosaurs using four previously published phylogenetic analyses. Later, with more taxa, Peters (2007) recovered pterosaurs and kin with the lepidosaur Huehuecuetzpalli (Fig. 3). In addition, ResearchGate.net holds an unpublished manuscript and figures redescribing Cosesaurus and kin much more accurately. The pterosaur referees did not want that manuscript published, having ignored the earlier ones for so long.

Figure 3. Oculudentavis added to the LRT.

Figure 3. Oculudentavis added to the LRT with previously untested  tritosaur lepidosaurs.

Ironically
Xing et al. noted in tiny Oculudentavis lepidosaur-like sclerotic (eyeball) bones and acrodont to pleurodont teeth extending below the orbit, as in modern lizards. Even with these clues, they did not add lepidosaurs to their analysis. They assumed from the start they had a tiny dinosaur-bird (with lepidosaur traits).

Figure 2. Cosesaurus running and flapping - slow.

Figure 4. Cosesaurus running and flapping. If you want to know what the Oculudentaivis post-crania looks like, this is the closest known sister taxon, slightly smaller than full scale.

Distinct from Cosesaurus,
(Fig. 2) the palate of Oculudentavis is solid below the rostrum. The antorbital fenestra is reduced. Damage to the skull displaced one ectopterygoid to the mid palate and broke the jugal. The post-crania remains unknown, but Cosesaurus (Fig. 4) is the most similar taxon.

From the Xing et al. 2020 abstract:
“Here we describe an exceptionally well-preserved and diminutive bird-like skull that documents a new species, which we name Oculudentavis khaungraae gen. et sp. nov. The find appears to represent the smallest known dinosaur of the Mesozoic era, rivalling the bee hummingbird (Mellisuga helenae)—the smallest living bird—in size. The O. khaungraae specimen preserves features that hint at miniaturization constraints, including a unique pattern of cranial fusion and an autapomorphic ocular morphology9 that resembles the eyes of lizards. The conically arranged scleral ossicles define a small pupil, indicative of diurnal activity. The size and morphology of this species suggest a previously unknown bauplan, and a previously undetected ecology.”

The authors saw lepidosaur traits not found in basal birds/tiny dinosaurs.
Rather than seeking and testing more parsimonious sister taxa elsewhere, the authors chose to follow their initial bias and described their find as an odd sort of tiny bird.

In a similar fashion
just a few days ago Hone et al. 2020 did much the same as they mistakenly described a large pteryodactylid, Luchibang, as a small istiodactylid, following their initial bias.

The LRT provides a wide gamut of 1656 taxa 
to test your next new taxon. Don’t make the same mistake as the above authors by assuming your odd little something is something it isn’t.


References
Ellenberger P and de Villalta JF 1974. Sur la presence d’un ancêtre probable des oiseaux dans le Muschelkalk supérieure de Catalogne (Espagne). Note preliminaire. Acta Geologica Hispanica 9, 162-168.
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2007.The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Xing L, O’Connor JK,; Schmitz L, Chiappe LM, McKellar RC, Yi Q and Li G 2020. 
Hummingbird-sized dinosaur from the Cretaceous period of Myanmar. Nature. 579 (7798): 245–249.

Thanks to Dr. O’Connor for sending a PDF of the Nature paper. 

wiki/Oculudentavis
www.researchgate.net

John Ostrom: The man who saved dinosaurs

Saw this on Facebook recently
The following is from an online Yale Alumni Magazine article (link below) by award-winning author, Richard Conniff, July/August 2014.

Preview
“In his book The Riddle of the Dinosaur, science writer John Noble Wilford added that Bakker “was the young Turk whose views could be dismissed by established paleontologists. Ostrom, however, could not be ignored.” Late in 1969, Ostrom took the challenge directly to the North American Paleontological Convention in Chicago, declaring in a speech that there was “impressive, if not compelling” evidence “that many different kinds of ancient reptiles were characterized by mammalian or avian levels of metabolism.” Traditionalists in the audience responded, Bakker later recalled, with “shrieks of horror.” Their dusty museum pieces were threatening to come to life as real animals.”

Figure 1. John Ostrom, from young paleo stud to elderly professorial type.

Figure 1. John Ostrom, as a young paleo stud and as an elder statesman several decades later demonstrating a degree of isometry and allometry during ontogeny.

“Against this false negative, Ostrom laid out the positive evidence, listing more than 20 anatomical similarities between Archaeopteryx and various dinosaurs. It wasn’t just that Ostrom could not be ignored. He was far too thorough and meticulous, and for 30 years too persistent in the face of his critics, for anyone to refute.”

The LRT has been online for only 8 years, so only 22 to go!

“Though one or two holdouts still resist the idea, it is now widely accepted that birds evolved from the group of bipedal theropod dinosaurs”

“The idea that birds are in fact living dinosaurs is so commonplace that the debate has largely turned to the question of why they were the only dinosaurs to survive the mass extinction of 65 million years ago.”

“More significantly, Ostrom lived to see his ideas about the dinosaur origin of birds—and the feathered plumage of dinosaurs—vindicated by a series of remarkable fossils from northeastern China.”

Those should have been unnecessary as Ostrom explains below.

“On Ostrom’s death in 2005, age 77, the Los Angeles Times wrote that he had “almost single-handedly convinced the scientific community that birds are descended from dinosaurs.” “John Ostrom,” the Sunday Times (London) added, “did more than anyone else to make dinosaurs interesting, real, and visceral.”

“When NPR’s All Things Considered marked the occasion by interviewing Ostrom’s first research student, Bob Bakker, the paleontological world held its breath for a moment, recalling the troubled relationship between these two allies in the dinosaur renaissance. But when asked how important Ostrom had been to dinosaur paleontology, Bakker graciously commented: “Nobody was more important.”

In the comments section to the online article,
you can read from Paul Sereno’s epitaph of Ostrom, “He did more than simply point out the great number of similarities between this theropod and the early bird Archaeopteryx. He argued that these similarities were derived. That is, that they were synapomorphies—shared morphology from common ancestry.”

We looked at Ostrom’s frustration with
the slow pace of paleontology earlier. Here it is again.

According to the Hartford Courant (2000), “In 1973, Ostrom broke from the scientific mainstream by reviving a Victorian-era hypothesis (see above) that his colleagues considered far-fetched: Birds, he said, evolved from dinosaurs. And he spent the rest of his career trying to prove it.” With the announcement of the first dinosaurs with feathers from China, Ostrom (then age 73) was in no mood to celebrate. He is quoted as saying, ““I’ve been saying the same damn thing since 1973, `I said, `Look at Archaeopteryx!’” Ostrom was the first scientist to collect physical evidence for the theory. Ostrom provoked a debate that raged for decades. “At first they said, `Oh John, you’re crazy,”’ Ostrom said in 1999.”

On the night Ostrom was to be honored
at the annual convention of the Society of Vertebrate Paleontology, I noticed him walking alone to the proceedings. I took advantage of the coincidence to walk with him. He was gracious enough to allow that. I cannot remember the substance of our conversation. As soon as we got to the building, he was swept up into the celebration as everyone else wanted their own moment with the man who saved dinosaurs.


References

https://pterosaurheresies.wordpress.com/2016/03/16/sometimes-it-takes-the-paleo-crowd-an-epoch-to-accept-new-data/

https://yalealumnimagazine.com/articles/3921-the-man-who-saved-the-dinosaurs?fbclid=IwAR1HMFU7cxeqn-iGd8dtO6nAxsjpERhyTza2AnpkCDz05k9fY3w-63-q4Wc

SVP abstracts – Ichthyornis and the origin of extant birds

Benito et al. 2019 dive into bird phylogeny
with a study of the Late Cretaceous toothed bird, Ichthyornis (Fig. 1).

Figure 1. Skull of Ichthyornis in 3 views from Field et al. 2018 and overall skeleton.

Figure 1. Skull of Ichthyornis in 3 views from Field et al. 2018 and overall skeleton.

From their abstract
“The origin of crown birds is poorly understood

By contrast, in the large reptile tree (LRT, 1592 taxa) the origin of crown birds is well understood back to Silurian jawless fish. Ichthyornis is a member of the clade of crown birds in the LRT, not an ancestor to it.

“…and the study of their early evolution must incorporate data from their closest relatives among Mesozoic stem birds. The postcranial morphology of the Late Cretaceous toothed bird Ichthyornis dispar may be more representative of the ancestral condition of crown birds than that of any other known Mesozoic avialan, and its study has crucial implications for understanding morphological evolution prior to the great radiation of the avian crown group.”

By contrast, in the LRT Vegavis (Latest Cretaceous) is basal to all extant birds including Mesozoic toothed birds like Icthyornis. It was a late survivor from an earlier genesis.

“Here we present high resolution scans of new, exquisitely preserved three dimensional specimens of Ichthyornis from the Late Cretaceous of Kansas. These correspond to a partial skeleton from a single individual, more complete and in better condition than the classic material known since the 19th Century. The new material includes a complete sternum and shoulder girdle with evidence of extensive pneumatization. This new skeleton shows certain morphological differences from the classic material, including the absence of some previously proposed autapomorphies of I. dispar. Thus, the new material may represent a previously unknown species, or it could indicate that morphological variation within I. dispar was greater than previously appreciated.”

Good to have these new data.

Figure 3. Subset of the LRT focusing on early birds, including Ichthyornis.

Figure 2. Subset of the LRT focusing on early birds, including Ichthyornis.

Benito et al. continue:
“Phylogenetic analyses incorporating our new morphological data corroborate recent results and recover a grade of predominantly marine taxa close to the origin of crown birds. I. dispar is recovered stemward of Hesperornithes and Iaceornis marshi, which is recovered as the sister taxon to all crown birds. Additional information on the crownward-most portion of the avian stem group will help confirm these results and provide critical information on the ancestral ecology of the crown bird radiation.”
I don’t know if Benito et al. employed all the taxa shown here (Fig. 2) in this subset of the LRT, but you can see Ichthyornis nests in the LRT within the clade of extant/crown birds. Here Ichthyornis is a highly derived member of its own small clade of toothed birds, within extant birds between megapodes and seriemas. Other taxa closer to the main line of Cretaceous bird evolution would probably make a better model for studies like this.

References
Benito J et al. 2019. New Ichthyornis specimens: shedding new light on modern bird origins. Journal of Vertebrate Paleontology abstracts.

The snakebird lacks external nares, breathes through its mouth

Figure 1. Skull of Anhinga rufa, an Old World relative of the New World Anhinga anhinga. Note the expansion of the maxilla (or overlying horny tissue) nearly obscuring the naris and antorbital fenestra. Compare to the loon in figure 3.

Figure 1. Skull of Anhinga rufa, an Old World relative of the New World Anhinga anhinga. Note the expansion of the maxilla (or overlying horny tissue) nearly obscuring the naris and antorbital fenestra. Compare to the loon in figure 2.

Anhinga anhinga (Linneaus 1766; 89cm) is the extant snakebird, which swims underwater and stabs its fish prey with its sharp beak, striking like a snake. It breathes only through the mouth as the bones and other hard tissues around the nostrils are overgrown. The feathers do not shed water, so some time is spent drying the feathers prior to flying. Snakebirds are related to grebes (genus: Aechmophorus) and loons (genus: Gavia, Fig. 2).

Figure 2. Skull of the common loon (Gavia stellata) showing the primitive state, with large external nares and antorbital fenestra.

Figure 2. Skull of the common loon (Gavia stellata) showing the primitive state, with large external nares and antorbital fenestra.

The large number and length of cervical vertebrae
in snakebirds (Fig. 3) is more or less matched only by flamingoes (genus: Phoenicopterus) by convergence.

Figure 3. Anhinga anhinga skeleton. Note the large number of cervical vertebrae. These enable the snake-like darting of the sharp skull while attacking prey underwater.

Figure 3. Anhinga anhinga skeleton. Note the large number of cervical vertebrae. These enable the snake-like darting of the sharp skull while attacking prey underwater.

Hackett et al. 2008 nested loons with penguins.
While close, the large reptile tree (LRT, 1562 taxa) nests loons + grebes derived from terns (genus: Thalasseus) and sisters to kingfishers (genus: Megaceryle) + jabirus (genus: Jabiru) and murres (genus: Uria) + penguins (genus: Aptenodytes). Among these taxa, only Jabiru experiences a reversal in having such long, stork-like legs, a primitive trait for extant birds.

Figure 1. The rostrum of Spinosaurus. Note the maxilla rising to close off the elongate naris into a reduced anterior and posterior opening.

Figure 4. The rostrum of Spinosaurus. Note the maxilla rising to close off the elongate naris into a reduced anterior and posterior opening.

Footnote:
Another aquatic dinosaur taxon that expanded its maxilla to shut off its nostrils was Spinosaurus (Fig. 4) as we learned earlier here.


References
Hackett S et al. 2008. A phylogenetic study of birds reveals their evolutionary history. Science 320:1763–1768.
Kennedy M et al. 2019. Sorting out the Snakebirds: The species status, phylogeny, and biogeography of the Darters (Aves: Anhingidae). Journal of Zoological Systematics and Evolutionary Research (advance online publication)
doi: https://doi.org/10.1111/jzs.12299 https://onlinelibrary.wiley.com/doi/10.1111/jzs.12299

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

Like Yi qi, the new Ambopteryx does NOT have bat wings

Wang, O’Connor, Xu and Zhou 2019
report on another scasoriopterygid with a ‘styliform’ bone creating a bat-like wing membrane in their imaginations. They named this specimen, Ambopteryx longibrachium (Fig. 1). This would be the second such instance, in their opinion, of a bat-wing bird. You might remember the flap over the first such instance, Yi qi (Fig. 2), which turned out NOT to have as styliform bone, just a displaced ulna on one side, a displaced radius on the other.

Figure 1. Photos and black tracing from Wang et al. 2019. Colors added here. There is no styliform bone on either wing. That is a displaced ulna... again.
Figure 1. Photos and black tracing from Wang et al. 2019. Colors added here. There is no styliform bone on either wing. That is a displaced ulna… again, as the reconstruction at upper left shows.

Well… tracing the elements in color
|reveals no styliform bone. See for yourself (Fig. 1). Again the authors mistook a perfectly good ulna for the invalid and imagined ‘styliform’ bone on the left wing. Turns out Ambopteryx longibrachium has a perfectly normal radius and ulna, just like all of its sisters in the bird clade. The authors do not illustrate a styliform bone on the better articulated right wing. It should have been there, if it was there in life.

Figure x. Closeup of the Ambopteryx forelimb. Here the purported radius + ulna is only the radius after crushing with two quarters of the exposed radius crushed neatly in half giving the impression of a radius + ulna, exactly the same length and without any interosseum space, which never happens in birds.
Figure x. Closeup of the Ambopteryx forelimb. Here the purported radius + ulna is only the radius after crushing with two quarters of the exposed radius crushed neatly in half giving the impression of a radius + ulna, exactly the same length and without any interosseum space, which never happens in birds.

The authors tried to make the extraordinary and implausible ordinary
by introducing another example of their previously invalidated observations. Today’s exercise demonstrates the importance of color tracing and using those tracings, as is, to build reconstructions. Do not freehand! The present notes also demonstrate, once again, just because some discovery is published in Nature, and heralded by major publications (see below) it still might not be true.

Figure 2. Yi qi tracing of the in situ specimen using DGS method and bones rearranged, also using the DGS method, to form a standing and flying Yi qi specimen. Note the lack of a styliform element, here identified as a displaced radius and ulna.

The news media is all over this:
with gorgeous paintings and glorified reports of a mythical creature with a bird body and bat wings. Unfortunately, like the editors and referees at Nature, they, too, were bamboozled by bombast.

www.nationalgeographic.com
www.smithsonianmag.com

Lead author Wang dramatically reported,
“I was frozen when I realized that a second membranous winged dinosaur was in front of my eyes,” Wang says. The 163 million-year-old fossil confirms that Yi was not an aberration or a one-off. Together, the two species represent an alternate evolutionary path for airborne dinosaurs.”

Not an aberration or a one-off, Dr. Wang…
two similar errors based on wishful thinking and cognitive bias.


References
Wang M, O’Connor JK.; Xu X and Zhou Z 2019. A new Jurassic scansoriopterygid and the loss of membranous wings in theropod dinosaurs. Nature 569: 256–259. doi:10.1038/s41586-019-1137-z
Xu X, Zheng X-T, Sullivan C, Wang X-L, Xing l, Wang Y, Zhang X-M, O’Connor JK, Zhang F-C and Pan Y-H 2015. A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings. Nature (advance online publication)
doi:10.1038/nature14423

reptileevolution.com/scansoriopterygidae2.htm

wiki/Yi_(dinosaur)
wiki/Ambopteryx

New passerine genomic study not confirmed by phenomic study

Oliveros et al. 2019
produced an exhaustive DNA study from 137 passerine families, then calibrated their phylogeny using 13 fossils to examine the effects of different events in Earth history on the timing and rate of passerine diversification.

Unfortunately
the large reptile tree (LRT, 1434 taxa) produced a different tree because it uses phenomic traits, not genes.

The two trees both started with birds of prey, including owls.
Then they diverged. The Oliveros team recovered 137 families of passerines arising from highly derived parrots, arising from highly derived owls.

The LRT recovered highly derived parrots arising from the more primitive hoatzin Opisthocomus, arising from the more primitive sparrow, Passer, arising from the more primitive grouse + chickens + peafowl and kin going back to Early Cretaceous Eogranivora. In the LRT owls give rise to birds of smaller prey: owlets, like Aegotheles, and swifts, like Apus, not herbivorous parrots.

Figure 1. Skeleton of the common house sparrow, Passer domestics.

Figure 1. Skeleton of the common house sparrow, Passer domestics. Note the heavy, seed-crunching beak, a precursor for the heavier see-crunching beak in parrots, not the other way around.

Among the traditional ‘passerines’ tested by the Oliveros team
are the distinctively different crows (genus Corvus) and nuthatches (genus Sitta). These clades nest apart from each other in the LRT and apart from Passer, the sparrow. In the LRT, crows and nuthatches are not Passerines, but parrots and hoatzins are passerines. Sometimes competing cladograms can be topsy-turvy like that, with similar sister taxa flipped with regard to primitive and derived. Earlier I mentioned ‘woodpeckers’, which have never been considered passerines, because woodpeckers and nuthatches are sisters in the LRT.

Robins (genus: Turdus) are considered passerines in the DNA study. They are crow relatives in the LRT. Jays (genus: Cyanocitta) and grackles (genus: Quiscalus) are crow relatives in the LRT. Neither are included in the DNA study that includes crows (genus: Corvus).

Figure 1. Several birds with zygodactyl feet (light red) and one member of the clade Zygodactylidae (red).

Figure 2. Subset of the LRT focusing on birds. This is how they are related to one another based on phenomic traits. Note the presence of Passer nesting between the chicken, Gallus and the parrot, Ara. Other purported passerines, like Turdus, Corvus and Sitta,  nest in other clades here.

So, once again,
when taxonomists use genomic (DNA) tests they run the risk of wasting their time when dealing with deep time taxa. Some paleo and bird workers put their faith in DNA, hoping it will recover relationships because it works well in humans. Unfortunately, too often phenomic tests are at odds with genomic tests to put  faith in genomic tests. Only phenomic (trait) tests recover cladograms that produce a gradual accumulation of traits among sister taxa, echoing deep time events. Only phenomic tests can employ fossils. Let’s not forget our fossils.

A suggestion for Oliveros et al. 2019:
test your results against your own phenomic study. If valid, both of your results will be the same. If not, one of your tests needs to be trashed.


References
Oliveros CH and 31 co-authors 2019. Earth history and the passerine superradiation.

www.pnas.org/cgi/doi/10.1073/pnas.1813206116

Avimaia and her enormous egg

Bailleul et al. 2019 reported
on the posterior half of an Early Cretaceous enantiornithine bird from China, Avimaia schweitzerae (IVPP V25371, Figs. 1,2), including an enormous eggshell within her torso. The authors commented on the eggshell, which had not one, but several several layers, an abnormal condition, probably leading to the demise of the mother.

Phylogenetic analysis
The Bailleul et al. 2019 phylogenetic analysis nested Avimaia with eight most closely related taxa, of which only one, Cathayornis (Fig. 1), was also tested in the large reptile tree (LRT, 1425 taxa, subset Fig. 3) and likewise nested with Avimaia. Significantly, Cathayornis also has a very deep ventral pelvis capable of developing and expelling very large eggs.

Figure 1. Avimaia compared to Cathayornis to scale.

Figure 1. Avimaia compared to Cathayornis to scale. Cathayornis is the only other tested enantiornithine bird to have such a deep ventral pelvis.

A long, thin, straight, displaced bone was found
beneath the rib cage and identified as a rib by Bailleul et al. 2019. I wonder if it is instead a radius (Fig. 1) because it is not curved like a rib and it does not have an expanded medial process. The radius is vestigial. Regardless of the identify of this slender bone, Avimaia, appears to be ill-suited for flying based on her robust tibiae, short dorsal ribs  and giant egg. Cathayornis (Fig. 1) appears to be better-suited for flying, based on its chicken-like proportions.

Figure 2. Avimaia in situ. Some bones were originally mislabeled. Here the egg is reconstructed with a more traditional egg shape.

Figure 2. Avimaia in situ. Some bones were originally mislabeled. Here the egg is reconstructed with a more traditional egg shape.

Mislabeled bones
The right ‘pubis’ (Fig. 2) is the right ischium. The reidentified pubis has a pubic boot and the ischium does, not as in sister taxa. The authors failed to identify vestigial pedal digit 5.

The egg was originally reconstructed as a sphere (drawn as a circle) inside the abdomen. Here (Figs. 1, 2) the egg is reconstructed in a more traditional egg shape more likely to pass through the ischia and cloaca.

Figure 2. Subset of the LRT focusing on the clade Enantiornithes and the nesting of Avimaia as a derived taxon within that clade.

Figure 3. Subset of the LRT focusing on the clade Enantiornithes and the nesting of Avimaia as a derived taxon within that clade.

Most birds
lay more than one egg in a clutch. Another exceptional bird that develops a very large egg is the flightless kiwi (Apterypterx, Fig. 4).

Figure 2. Jurapteryx, Pseudocrypturus, Apteryx and Proapteryx to scale.

Figure 2. Jurapteryx, Pseudocrypturus, Apteryx and Proapteryx to scale.


References
Bailleul AM, et al. 2019. An Early Cretaceous enantiornithine (Aves) preserving an unlaid egg and probable medullary bone. Nature Communications. 10 (1275). doi:10.1038/s41467-019-09259-x
Pickrell, J 2019. “Unlaid egg discovered in ancient bird fossil”. Science. doi:10.1126/science.aax3954

wiki/Avimaia

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