Post K-T event birds were all non-arboreal…

…whether tested using DNA or skeletal traits…

Field et al. 2018
used DNA to produce a cladogram of extant birds to determine that basal taxa were all non-arboreal. Earlier the large reptile tree (LRT, 1121 taxa) came to the same conclusion using trait analysis and fossils (Figs. 1, 2). The only difference is the Field team determined that the crown bird radiation was post-Cretaceous. The LRT recovered a crown bird radiation in the post-Jurassic and post-Cretaceous birds were also non-arboreal (Fig. 1, 2). An earlier radiation explains the Paleocene appearance of very derived fossil penguins and the Early Cretaceous appearance of the fossil chicken, Eogranivora.

Figure 2. Basal bird phylogeny based on the LRT (morphology)

Figure 1. Basal bird phylogeny based on the LRT (morphology.

Unfortunately
Field et al. also recovered flamingos with grebes, chickens with ducks, and many other physical trait mismatches, like those in Prum et al. 2015. Such mismatches are ignored by DNA workers.

Figure 1. Click to enlarge. Duck origins recovered by the LRT. Duck descendants were long-legged walkers and later waders.

Figure 2. Click to enlarge. Duck origins recovered by the LRT. Duck descendants were long-legged walkers and later waders.

From the Field et al. 2018 abstract:
“We suggest that ecological filtering due to the temporary loss of significant plant cover across the K-Pg boundary selected against any flying dinosaurs (Avialae) committed to arboreal ecologies, resulting in a predominantly non-arboreal post-extinction neornithine avifauna composed of total-clade Palaeognathae, Galloanserae, and terrestrial total-clade Neoaves that rapidly diversified into the broad range of avian ecologies familiar today. The explanation proposed here provides a unifying hypothesis for the K-Pg-associated mass extinction of arboreal stem birds, as well as for the post-K-Pg radiation of arboreal crown birds.”

Unfortunately
the loss of an arboreal habitat due to world-wide fires does not explain the disappearance of the Cretaceous toothed sea birds, Ichthyornis and Hesperornis. Other explanations must be invoked.

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

Figure 3. More fossil taxa, updated tree, new clade names. Note the derived position of the penguin Aptenodytes, with with fossil penguins in the Paleocene.

The mechanism for crown birds invading trees
appears to have been neotony, with chick-sized adults with short legs and short necks arising from larger, long-legged, long-necked predecessors (e.g. Passer the sparrow and Opisthocomus, the hoatzin, arising  from Gallus, the chicken). Notably the hatchlings of arboreal taxa are typically not precocial, hatching out a more helpless stage in their ontogeny and growing to fledgling size rapidly.

Field et al. correctly report,
“…virtually the entirety of the avian crown-group fossil record is restricted to sediments of Cenozoic age, and the earliest well-supported crown bird fossil is scarcely older than the end-Cretaceous, at approximately 67 Ma.” True. This is one of the unresolved mysteries of paleontology, only now starting to crack with discoveries like Eogranivora, the early Cretaceous chicken, and the nesting of Cretaceous toothed birds between paleognaths and neognaths (Fig. 3), something the Field analysis was not able to recover.

Figure 1. Megapodius is the extant bird nesting at the base of all neognathae (all living birds except ratites).

Figure 4. Megapodius is the extant bird nesting at the base of all neognathae (all living birds except ratites). Post K-T event birds look more or less like this one. One might ask, if all the adults were killed, would the precocious hatchlings, hidden beneath thick mounds, form the first generation of K-T event survivors?


One might ask,

if all adult birds worldwide were killed on exposure to oven-like temperatures and subsequent lack of trees, would the buried, precocious hatchlings of mound-builders, like Megapodius (Fig. 4), create the first generation of K-T event bird survivors? If so, perhaps the tinamou ancestors of modern tinamous and ratites were likewise mound builders. Currently tinamous and ratites are not mound-builders.

Basal members of all bird clades in the LRT
appear to have survived the K-T event, based on the Paleocene presence of fossil penguins, like Waimanu (Fig. 5). Overlooked by Field et al., basal members of all the major crown bird clades in the LRT (Fig. 3) are all non-arboreal, long-legged, wading taxa (Fig. 2), that do not nest in trees.

Figure 1. The world at the K-T boundary, 65 mya and the distribution of Paleocene birds.

Figure 5. The world at the K-T boundary, 65 mya and the distribution of Paleocene birds.

References
Field  DJ et al. (7 co-authors) 2018. Early Evolution of Modern Birds Structured by Global Forest Collapse at the End-Cretaceous Mass Extinction. Current Biology (advance online publication) DOI: https://doi.org/10.1016/j.cub.2018.04.062

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Kiwi ancestors

Worthy et al. 2013 reported:
“Until now, kiwi (Apteryx owenii, Apterygidae, Shaw 1813; Fig. 1) have had no pre-Quaternary fossil record to inform on the timing of their arrival in New Zealand or on their inter-ratite relationships.” They described two fossils (femur and quadrate) from the Early Miocene (Fig. 1; 19–16mya) which they named Proapteryx. “The new fossils indicate a markedly smaller and possibly volant bird, supporting a possible overwater dispersal origin to New Zealand of kiwi independent of moa. If the common ancestor of this early Miocene apterygid species and extant kiwi was similarly small and volant, then the phyletic dwarfing hypothesis to explain relatively small body size of kiwi compared with other ratites is incorrect.

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

Figure 2. Jurapteryx, Pseudocrypturus, Apteryx and Proapteryx to scale. In lateral view it is difficult to see the width of the ventral pelvic elements. They are not as wide as the egg diameter. Note the lack of a pygostyle in all three taxa.

By contrast
the large reptile tree (LRT, 1213 taxa) nest the kiwi with Pseudocrypturus (Houde 1988; Early Eocene) apart from other ratites, as the basalmost birds with living representatives.

Apteryx owenii (Shaw 1813) The extant flightless kiwi has an elongate naris that extends to the tip of its beak. Maybe two teeth are there. Here it nests with Pseudocrypturus, but flightless traits push it toward Struthio, by convergence. in the pre-cladistic era, Calder (1978, 1984) considered the kiwi a phylogenetic dwarf derived from the larger moa, but that was invalidated by Worthy et al. 2013 and the large reptile tree.

Proapteryx micromeros (Worthy et. al. 2013) was a slender, tiny Miocene (18 mya) ancestor likely capable of flight.

Pseudocrypturus cercanaxius (Houde 1988; Early Eocene) was originally considered a northern hemisphere ancestor to ratites (like the ostrich, Struthio). Today these primitive flightless birds are chiefly restricted to the southern hemisphere. It could be that early birds did start in the South and had migrated to the North during the Paleocene (66-56 mya).

Since ratites are basal to extant birds, and Pseudocrypturus is basal to ratites (paleognaths), Pseudocrypturus is also quite similar to the ancestor of all extant birds despite its late appearance in the early Eocene. Perhaps something very much like it was one of the few survivors of the K-T extinction event.

It’s notable that Pseudocrypturus has long legs. Early ducks, like Presbyornis, and basal raptors, like Sagittarius, also had long legs. Evidence is building that this is the primitive condition for the clade of living birds arising from the K-T extinction event.

Worthy et al. nest Apteryx
within the order Casuariiformes, which includes cassowaries, emirs, and kiwi, but only in the absence of Pseudocrypturus.

The kiwi egg vs ventral pelvis issue
In most tetrapods, including humans, the egg/baby passes through the cloaca/vagina which passes through the two ischia. That was also likely the case with Archaeopteryx, because this is also the case with Gallus the chicken. In extant birds the ischia posterior tips no longer touch, but are widely separated. Going several steps further, in the kiwi the enormous egg is held in front of the pubis (Fig. 1), which is also in front of the ischia.

The following video of a kiwi laying an egg
shows the cloaca a substantial distance below the swirl that marks its tail. kiwi egg video click to play pretty much located at the tip of the long axis of the egg in figure 1 (maybe a little higher/closer to the tail).

Figure 2. Kiwi laying an egg. Click to play.

Figure 2. Kiwi laying an egg. Click to play.

In the LRT
Pseudocrypturus and Apteryx (Fig. 1) nest together and apart from the ratites. Pseudocrypturus is basal to all living birds. It probably first appeared in the Early Cretaceous. It was found in the Paleocene.

References
Calder WA 1978. The kiwi. Scientific American 239(1):132–142.
Calder WA 1984. Size, function and life history. 448 pp. Cambridge (Harvard U Press).
Houde PW 1986. Ostrich ancestors found in the northern hemisphere suggest new hypothesis of ratite origins. Nature 324:563–565.
Houde PW 1988. Paleognathus birds from the early Tertiary of the northern hemisphere. Publications of the Nuttall Ornithological Club 22. 147 pp.
Shaw 1813. Naturalist’s Miscellany 19:
Worthy, TH. et al. (5 coauthors) 2013. Miocene fossils show that kiwi (Apteryx, Apterygidae) are probably not phyletic dwarves. Paleornithological Research 2013, Proceedings of the 8th International Meeting of the Society of Avian Paleontology and Evolution. Retrieved 16 September 2017.

wiki/Pseudocrypturus
wiki/Apteryx, Kiwi
wiki/Proapteryx

The assembly of the avian body plan (Cau 2018) pt. 3 of 3

Yesterday and the day before we looked at parts 1 and 2 of the Cau 2018 tree topology of theropods leading to birds (Fig. 3). Today: part 3 of 3.

Node 19. Maniraptora: (Alvarezsauroidea + Pennaraptora) Here’s where the second Compsognathus (CNJ79) would affect the Cau topology. The basal member of Maniraptora in the Cau tree is Jianchangosaurus, which has a toothless premaxillla and nests with therizinosaurs traditionally and in the LRT (Fig. 5). You don’t want a toothless premaxilla at this basal node because most succeeding taxa have premaxillary teeth. In the LRT, Jianchangosaurus is a derived therizinosaur, close to a surprise tiny therizinosaur with long forelimbs and a trenchant pedal digit 2, Rahonavis. That may change or be confirmed with more complete specimens.

The LRT agrees with Cau in nesting Shuvuuia with Haplocheirus.

Figure 1. Jianchangosaurus nests at the base of the Maniraptora in Cau 2018, but with therizinosaurs in the LRT.

Figure 1. Jianchangosaurus nests at the base of the Maniraptora in Cau 2018, but with therizinosaurs in the LRT, where it nests with Rahonavis.

Figure 2. Rahonavis nests in the LRT as a tiny derived therizinosaur based on the few bones currently known.

Figure 2. Rahonavis nests in the LRT as a tiny derived therizinosaur based on the few bones currently known.

Node 20. Pennaraptora (Oviraptorosauria + Paraves) The Cau study and the LRT agree that Caudipteryx and Khaan nest together. Lacking from the Cau study, Limusaurus (Fig. 1) nests as a basal oviraptorid in the LRT. In turn the Cau study includes taxa not listed in the LRT.

Node 21. Paraves: Distinct from the Cau tree, the LRT nests Microraptor with Ornitholestes and apart from Deinonychus and Velociraptor. The LRT nests Fukuiraptor with Zhenyuanlong with tyrannosaurs. The Cau study does not include Zhenyuanlong. 

Figure 1. The origin of birds cladogram according to Cau 2018. Taxon exclusion forces a mixup of basal taxa.

Figure 3. The origin of birds cladogram according to Cau 2018. Taxon exclusion forces a mixup of basal taxa.

Node 22. Averaptora: In the Cau study Sinovenator nests with Jinfengopteryx and Mei. In the LRT, Jinfengopteryx (Fig. 4) nests as a basal troodontid, derived from a sister to Velociraptor and Haplocheirus. Sinovenator nests closer to birds. Mei nests within birds (Scansoriopterygidae). Yi and Epidexpteryx are also scansoriopterygids. Cau nests them basal to Archaeopteryx.

 Jinfengopteryx, a basal troodontid in both studies.

FIgure 4. Jinfengopteryx, a basal troodontid in both studies. Think of this taxon like a neotonous velociraptor, leading to all troodontids including (with further neotony) birds. Note the resemblance to Solnhofen birds.

Employing only one Archaeopteryx in the Cau study
overlooks the variety in Solnhofen birds recovered by the LRT. When this is repaired with more taxa, let’s see what happens when more Solnhofen birds are added (Fig. 5):

Figure 1. Cladogram subset of the LRT focusing on Theropoda.

Figure 4. Cladogram subset of the LRT focusing on Theropoda, including extant birds.

As we learned
earlier, no two Solnhofen birds are identical. In the LRT they are distinct enough to nest in several basal bird clades. This was completely missed by Cau and most other bird workers.

Missing from the Cau taxon list
are any living birds. In the LRT, the toothed Cretaceous birds nest between paleognaths and neognaths, so that branch was missed.

Sometimes
taxon exclusion adversely affects tree topologies. Start with a wide gamut analysis (Fig. 5) that sets limits on the more focused study that you want to look at.

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

The assembly of the avian body plan (Cau 2018) pt. 2 of 3

Yesterday we looked at part 1 of the Cau 2018 cladogram of theropods (including birds). Certain taxa within this study were new to me, so I added several to the the large reptile tree (LRT, 1213 taxa). Today we’ll continue with Node 9, still within the Huxley stage of theropod evolution.

Figure 2. Zuolong skull revised with a backward tilting lacrimal and other minor modifications.

Figure 1. Zuolong skull revised with a backward tilting lacrimal and other minor modifications.

Node 9. Tetanurae: (Zuolong + Chilesaurus + Neotetanurae). Adding Zuolong to the LRT nests it as a basal theropod, basal to the rarely tested taxa in the Segisaurus + Marasuchus + Procompsognathus clade (Fig. 2). Zuolong is the first of these with a relatively complete skull. Cau 2018 nest Zuolong and the phytodinosaur, Chilesaurus, with Neotetanurae apparently by excluding certain relevant taxa.

Figure 1. Chilesaurus and kin, including Damonosaurus and basal phytodinosauria.

Figure 2. Chilesaurus and kin, including Damonosaurus and basal phytodinosauria. No close relatives of theropods here!

Node 10. Chilesaurus + Neotetanurae: (See node 9). Cau also reports, “The parsimony analysis confirms the basal tetanuran affinities of the enigmatic Chilesaurus and dismisses ornithischian relationships suggested by Baron & Barrett (2017).” This is only true base on taxon exclusion. Add back the missing taxa, like Daemonosaurus , Jeholosaurus and Haya and the tree topology will change.

Figure 1. The origin of birds cladogram according to Cau 2018. Taxon exclusion forces a mixup of basal taxa.

Figure 1. The origin of birds cladogram according to Cau 2018. Taxon exclusion forces a mixup of basal taxa.

Node 11. Neotetanurae (Carnosauria + Coelurosauria): The Cau tree and LRT share many taxa here, including Allosaurus with Sinraptor and Acrocanthosaurus. The Cau tree has only one Compsognathus. The LRT has two, each at the base of its own clade. The Cau tree nests Megalosaurus between the phytodinosaur, Chilesaurus, and the small compsognathid, Aorun, which is odd on the face of it (= no gradual accumulation of traits).

Node 12. Coelurosauria: The LRT indicates that Sinocalliopteryx does not belong in this clade, as Cau recovers it, but Sinocalliopteryx nests much more primitively, basal to Coelophysis and kin.

Nodes 13. Compsognathid grade + Tyrannoraptora: The spinosaurs and kin are not present in the Cau taxon list. When present these long rostrum taxa attract Guanllong and Megaraptor to more primitive theropods, away from tyrannosaurs, despite convergent traits.

Node 14. Sinocalliopteryx + Tyrannoraptora: See Node 13.

Node 15. Tyrannoraptora: (Tyrannosauroids and maniraptoromorphs) See Node 13.

Node 16. Maniraptoromorpha: (includes Vultur, excludes Tyrannosaurus). This definition is a little vague. Wish it had at least one included basal taxon. In the Cau tree Coelurus is a basal taxon. Unfortunately, too little of it is known to add it to the LRT.

Node 17. Ornitholestes + Maniraptoriformes: Distinct from the Cau tree, Ornitholestes is basal to microraptorids and tyrannosaurs, as well as dromaeosaurs, troodontids and birds.

Node 18. Maniraptoriformes: (Ornithomimosauria + Maniraptora). Distinct from the Cau tree, ornithomimosaurs in the LRT are derived directly from the holotype of Compsognathus, separate from oviraptorids and dromaeosaurs, closer to tyrannosaurs and kin. The LRT nests Ornitholestes and kin on the bird side of therizinosaurus + oviraptorids. The Cau tree does the opposite.

Figure 1. Cladogram subset of the LRT focusing on Theropoda.

Figure 2. Cladogram subset of the LRT focusing on Theropoda.

Part 3 tomorrow.

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

 

Eozygodactylus: a basal roadrunner, not a ‘songbird’

Today: a little, long-legged bird from the Green River formation
Eozygodactylus americanus (Weidig 2010; Eocene; 53mya; FMNH PA726) Originally considered a perching songbird related to Passer (the sparrow), this long-legged, lakeshore wading bird (think: sandpiper), nests with Geococcyx (the roadrunner) in the large reptile tree (LRT, 1224 taxa). Like Geococcyx (the roadrunner), pedal digit 4 is also retroverted (= zygodactyl). The right (lower) femur appears to be broken in two.

Figure 1. Eozygodactylus in situ with two lighting schemes and bones colorized.

Figure 1. Eozygodactylus in situ with two lighting schemes and bones colorized. If pterosaurs had survived the K-T event, this is where we would find them.

As a basal taxon,
Eozygodactylus was derived from the predatory bird clade, the toothed bird clade and, more distantly, Megapodius (the mound builder). Eozygodactylus has a relatively large skull and short rostrum, which might suggest a possible juvenile stage. No related adult taxa (Figs. 4, 5) have similar proportions.

Figure 2. Eozygodactylus reconstructed from figure 1.

Figure 2. Eozygodactylus reconstructed from figure 1. Not sure how deep the sternum is. Sister taxa can fly, but prefer to walk.

Closely related basal neognath birds include
long-legged screamers (genus: Chauna) at the base of the sparrow/chicken/parrot clade and long-legged stone curlews (genus: Burhinus) at the base of crows + jays + woodpeckers + swallows. By convergence, woodpeckers also have a zygodactylus pes. Apparently this trait comes and goes, without a single long zygodactyl lineage.

Figure 3. Psophia the trumpeter in vivo and skeleton.

Figure 3. Psophia the trumpeter in vivo and skeleton, a close relative of Eozygodactylus, larger and without a zygodactylus foot.

The nesting of Eozygodactylus
at the base of a basal bird clade supports the antiquity of long-legged shore birds (Figs. 4, 5) in the evolution of birds, distinct from traditional and DNA tree topologies.

Figure 1. Click to enlarge. Duck origins recovered by the LRT. Duck descendants were long-legged walkers and later waders.

Figure 4. Click to enlarge. Duck origins recovered by the LRT. Duck descendants were long-legged walkers and later waders.

Figure 2. Basal bird phylogeny based on the LRT (morphology)

Figure 5. Basal bird phylogeny based on the LRT (morphology)

References
Weidig I 2010. New Birds from the Lower Eocene Green River Formation, North America. Records of the Australian Museum 62:29-44.

Nat Geo: These are the dinosaurs that didn’t die.

Figure 1. Messel swift (48 mya) from the Nat Geo bird article.

Figure 1. Messel swift (48 mya) from the Nat Geo bird article.

A recent edition of National Geographic
featured an article on bird evolution by Victoria Jaggard with photographs by Robert Clark and many illustrations. Unfortunately, they relied on DNA for their cladogram, featuring an apologetic illustration of a dissimilar grebe and flamingo arising from a common stem (Fig. 2). Dissimilar taxa are never closely related in trait analysis, but DNA analysis keeps finding such pairs in birds, always with the vague hope/faith/belief that someday this will resolve itself with new transitional discoveries. According to the large reptile tree (LRT, 1206 taxa) that will never happen as both flamingos and grebes each have a long list of more similar sisters, cousins and second-cousins that intervene between these two.

Figure 2. Flamingo and grebe illustration from Nat Geo article on birds.

Figure 2. Flamingo and grebe illustration from Nat Geo article on birds.

When it comes to fossils
Nat Geo is still stuck in the stone age as they conflate all Solnhofen birds into a single genus, Archaeopteryx, no doubt following the advice of certain professional avian paleontologists resting on tradition and an unwillingness to test specimen-based taxa. In the LRT the many Solnhofen birds are a diverse assemblage, not a single genus.

Figure 3. Vegavis being chased by a dromaeosaur in the Latest Cretaceous of Antarctica. Dr. Julia Clarke considered Vegavis an early duck. The LRT nests it with tinamou-like birds.

Figure 3. Vegavis being chased by a dromaeosaur in the Latest Cretaceous of Antarctica. Dr. Julia Clarke considered Vegavis an early duck. The LRT nests Vegavis as the long-legged tinamou-like outgroup to all living birds.

Relying on the work of Dr. Julia Clarke,
Nat Geo nests the outgroup all living birds in the LRT, Vegavis (Figs, 3, 4), as a basal chicken/duck and beautifully illustrates it as a merganser-like taxon with short swimming legs (Fig. 3). In reality we don’t have the skull of Vegavis and the legs are quite long and slender (Fig. 4), like those of the most primitive of all living birds, tinamou-like taxa.

Figure 4. Vegavis skeleton (gray parts restored) compared to duck skeleton.

Figure 4. Vegavis skeleton (gray parts restored) compared to duck skeleton.

Regarding the K-T extinction-survival event, Jaggard wrote:
“Depending on whom you ask, smaller bodies, polar adaptations, seed-based diets, and even nest designs may have played roles in determining who lived and who died. Solving the mystery will almost certainly require exhaustive hunts for animals that lived even closer in time to the impact. Ongoing fieldwork in places like South America, New Zealand, and the frosty deserts of Antarctica already hint at fresh discoveries in the near future.”

Although Vegavis fossils seem to form a bottleneck for birds in the latest Cretaceous, the present diversity of later birds arises from early Cretaceous taxa, including a clade of toothed birds like Hangshanornis, basal chickens, like Eogranivora, and the appearance of highly derived birds, like basal penguins, shortly after the K-T extinction event. We also find Vegavis-like taxa in the Early Cretaceous.

Jarrard continues:
“And richer genetic clues should flood the field in the coming years. At the China National GeneBank in Shenzhen, scientists are using faster, more precise techniques to churn out drafts of entire genomes for all living bird species by 2020. Their work should help researchers not only to understand living birds but also to match useful traits in fossil animals to those in the animals’ living descendants.”

That’s unfortunate because after testing we already know
DNA does not always work with birds. Bird workers believe in DNA, hoping that someday it will produce a tree topology in which all sister taxa will look like one another, gradually blending on adjacent branches. Unfortunately, trait analysis demonstrates that day will never come. There are just too many intervening taxa.

Please, let’s all get back to trait analysis.
I’ve shown that it can be done. DNA, at least with regard to birds, is just not working.

References
Jaggard V. 2018. These are the Dinosaurs that didn’t die. Nat Geo online

Variation within Confuciusornis

A new paper
by Elzanowski, Peters (no relation) & Mayr 2018 studies the temporal region of Confuciusornis (Early Cretaceous, 125 mya) and other birds. The team writes: “their skull presents a puzzle because it is said to have retained the diapsid temporal region of their avian ancestors (Peters and Ji, 1998; Hou et al., 1999), which is discordant with their phylogenetic position and other cranial features that are much more derived relative to Archaeopteryx.”

Unfortunately
Elzanowski et al. make the traditional mistake of assuming all Solnhofen birds are congeneric (= all Archaeopteryx). They are not. Wellnhoferia (formerly Archaeopteryx) grandis (BSP 1999, Fig. 4) is a basal confuciusornithid in the large reptile tree (LRT, 1191 taxa). Therefore, the traits found in Confuciusornis cannot be “much more derived relative to Archaeopteryx”. The team also does not realize the pygostyle evolved several times by convergence (in the LRT).

Based on taxon exclusion
Elzanowski et al. make several phylogenetic assumptions that are not validated in the LRT. They write, “Confuciusornis sanctus has been heralded as a bird with an ancestrally diapsid skull, although this does not match its phylogenetic position as determined by other skeletal features.” They also seem to have missed several traits in their tracing of the Berlin specimen (Fig. 1).

Figure 1A. Berlin Confuciusornis skull as traced by Elzanowski et al. and colorized here. Note the postorbital is broken during crushing. Hyoids are misidentified. Lacrimal and teeth are overlooked. The vomer and palatine are peeking out from the anterior maxilla. The plesiomorphic diapsid temporal region is present here (contra Elzanowski et al. 2018).

Figure 1A. Berlin Confuciusornis skull as traced by Elzanowski et al. and colorized here. Note the postorbital is broken during crushing. Hyoids are misidentified. Lacrimal and teeth are overlooked. The vomer and palatine are peeking out from the anterior maxilla. The plesiomorphic diapsid temporal region is present here (contra Elzanowski et al. 2018).

Figure 1B. Confuciusornis Berlin specimen teeth.

Figure 1B. Confuciusornis Berlin specimen teeth.

The Berlin MBAv1168 specimen
is distinct from the GMV specimen in several ways (Fig. 2). The MBAv1168 specimen is twice as tall, has a longer neck, shorter tail, smaller, wider sacrum, larger unguals and a longer pedal digit 4 among other traits. The Berlin specimen has tiny teeth (overlooked by Elzanowski et al in Fig. 1), like all related taxa except the GMV specimen. In the LRT the MBAv1168  specimen nests with Changchengornis (Fig. 4), not Confuciusornis (due to the presence of teeth and other traits).

Figure 2. The GMV and MBAv specimens to scale. See text for details.

Figure 2. The GMV and MBAv specimens to scale. See text for details and differences.

The Berlin specimen is preserved with many feathers,
including the two elongate tail feathers that mark this as a male (Fig. 3).

Figure 3. The Berlin specimen assigned to Confuciusornis sanctus is preserved with a full set of feathers, including two long tail feathers. Surprisingly, the furcula came to rest on top of the neck.

Figure 3. The Berlin specimen assigned to Confuciusornis sanctus is preserved with a full set of feathers, including two long tail feathers. Surprisingly, the furcula came to rest on top of the neck.

Other confuciusornthids
tested here include the taxa in figure 4.

Figure 4. Confuciusornithiformes to scale. Note the lack of a pygostyle in the majority of taxa.

Figure 4. Confuciusornithiformes to scale. Note the lack of a pygostyle in the majority of taxa.

Hundreds of Confuciusornis specimens are known.
Only two have been tested in the LRT. Elzanowski et al. had first hand access to the Berlin specimen and others. I relied on published photographs and color tracings of the elements and creating reconstructions to replace displaced bones to their in vivo positions.

References
Elzanowski A, Peters DS & Mayr G 2018. Cranial morphology of the Early Cretaceous bird Confuciusornis. Journal of Vertebrate Paleontology Article: e1439832. DOI: 10.1080/02724634.2018.1439832.

wiki/Confuciusornis