Screamers: the return of digit ‘0’

Screamers are extant birds
in the family Anhimae. They include the genera Chauna (Oken 1816; Southern screamer; up to 90 cm in length) and Anhima (Brisson 1760; horned screamer). The clade lacks uncinate processes on the ribs. but has large spurs on the metacarpus (Figs. 1, 2). The young are precocial (able to run soon after hatching). This is a rather primitive and very vocal clade.

The Anhimae clade was considered closest
to ducks (Anatidae) based on DNA, but the rostrum, as you can see (Fig. 1) lacks many duck-like traits.

By contrast,
the large reptile tree (LRT, 1065 taxa), grounded on morphology, nests Chauna at the base of the chicken, sparrow and parrot clade.

Fig. 1. Anhima skeleton and skull.

Fig. 1. Anhima skeleton and skull.

The manus of screamers is atypical
(Fig. 2) in that large spurs arise from the distal metacarpus (as a new ossification) and from the proximal metacarpus (as the return of digit ‘0’, a digit first brought to light with the Limusaurus discovery and misinterpretation). Along with the return of digit ‘0’ we also find fused vestiges of digits 4 and 5.

Fig. 2. Screameer manus showing the full expression of digit 0 at the base of the metacarpals producing a large anteriorly-directed spur.

Fig. 2. Screameer manus showing the full expression of digit 0 at the base of the metacarpals producing a large anteriorly-directed spur. Faint vestiges of digits 4 and 5 are also present.  Note how easy color explains things by clearing segregating one bone from another, even when they fuse.

You won’t find any references to digit ‘0″
in the academic literature. That reversal in theropods and birds was first hypothesized here a few years ago, and well documented above (Fig. 2).

References
Brisson MJ 1760. Ornithologie, ou, Méthode contenant la division des oiseaux en ordres, sections, genres, especes & leurs variétés : a laquelle on a joint une description exacte de chaque espece, avec les citations des auteurs qui en ont traité, les noms quils leur ont donnés, ceux que leur ont donnés les différentes nations, & les noms vulgaires
Oken L 1816. Lehrbuch der Zoologie (or Lehrbuch der Naturgeschichte 1–3. Theil. Zoologie ; 2. Abt. Fleischthiere) Jena.

wiki/Anhima
wiki/Chauna

 

Flamingoes are taller, skinnier seriemas, according to the LRT

Updated January 09, 2018 with photos of flamingo and seriema in vivo.

Figure 1. Phoenicopterus, the flamingo is closest to Cariama, the seriema, (Fig. 2) in the LRT.

Figure 1. Phoenicopterus, the flamingo is closest to Cariama, the seriema, (Fig. 2) in the LRT.

 

When you see them together,
(Figs. 1, 2) it’s pretty obvious. Flamingoes and seriemas share a long list of traits. Oddly, in Wikipedia, both are considered ‘sole representatives’ of their respective orders. Closest representatives have wavered from storks to ibises to ducks and geese like Presbyornis, even doves!

Prum 2015
nests Phoenicopterus with Rollandia, the flightless Lake Titicaca grebe (a type of diving bird) using DNA. Hackett et al. 2008 nested Phoenicopterus with Podiceps, another grebe, also using DNA.

Figure x. Cariama cristatus, the seriema in several views.

Figure x. Cariama cristatus, the seriema in several views. Here the downturned beak of the flamingo is just beginning to turn down.

As it turns out,
the secretary bird, Sagittarius, is closer to the prehistoric ‘terror birds’ or phorushacids, than is their traditional extant representative, Cariama, the seriema. Both secretary birds and phorushracids had a high snout with a dorsal naris, among many other traits in common.

References
Hackett S et al. 2008. A phylogenetic study of birds reveals their evolutionary history. Science 320:1763–1768.
Prum RO et al. (6 co-authors) 2015. A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing. Nature doi:10.1038/nature15697

wiki/Flamingo

Snake origins according to DNA studies

Figure 1. Cladogram of squamates from Streicher and Wiens 2017 highlighting the origin of snakes based on DNA. Unfortunately, only the closely related taxa are correctly nested here. See figure 2 for gradual accumulations of traits in all related taxa.

Figure 1. Cladogram of squamates from Streicher and Wiens 2017 highlighting the origin of snakes based on DNA. Unfortunately, only the closely related taxa are correctly nested here. See figure 2 for gradual accumulations of traits in all related taxa.

 

Why would Streicher and Wiens 2017
(Fig. 1) want to do this? They can’t use fossils. They’ll never find a gradual accumulation of traits, starting from ‘snakes with legs’. And… DNA does not work over large phylogenetic distances. They put their faith in DNA. They believed they would get an answer. Their prayers were answered, but the answer does not make sense. Their cladogram cannot be verified with morphological studies (Fig. 2). Morph studies can and do use fossils and do produce a gradual accumulation of traits. Morphology is, and will always be, the gold standard of phylogenetics.

We have to stop wasting time
on methods that do not work over large phylogenetic distances. Rant. Rant. Rave. Rave.

Figure 2. Subset of the large reptile tree focusing on lepidosaurs and snakes are among the squamates.

Figure 2. Subset of the large reptile tree focusing on lepidosaurs and snakes are among the squamates.

Here’s how you know, at first glance,
how the Streicher and Wiens cladogram produces odd, mismatching sisters.

  1. Derived taxa usually do not appear at the base of major clades: Dibamus, Typhlops
  2. Mismatches usually do not nest close to one another: Bipes & Lacerta, Python & Typhlops, Dibamus & Sphenodon

Streicher and Wiens will never find out
that snake ancestors had legs using DNA. Those just never shows up in molecules. Their paper’s title: “Phylogenomic analyses of more than 400 nuclear loci resolve the origin of snakes among lizards families” do not resolve the origin of snakes.

Snakes arise
from near the very beginning of a rapidly diversifying Scleroglossa. The snake clade split from the gekko clade shortly after the origin of the Squamata. Derived burrowing snakes with jaws that pull prey items in appear in derived taxa, not as basal plesiomorphic forms. When basal taxa are bland and plesiomorphic, that’s a good sign that you’re doing something right.

References
StreicherJW and Wiens JJ 2017. Phylogenomic analyses of more than 400 nuclear loci resolve the origin of snakes among lizards families. Biology Letters 13: 20170393.
http://dx.doi.org/10.1098/rsbl.2017.0393

 

 

LRT sheds light on Gastornis: its a giant flightless parrot!

I left adding extant birds to the LRT for last
because I thought the phylogeny of birds was already set in stone using extant bird DNA (Hackett et al. 2008; Prum et al. 2015). Now I’m learning that, once again, DNA does not replicate morphological analyses in birds over large phylogenetic differences.

I’m learning about post K-T birds step-by-step
as I meet them, one-by-one, as usual. Some surprises are popping up. Last time we looked at the giant bird Gastornis (Fig. 1, 6), it nested with the hoatzin, or stink bird, Opisthocomus. It still does so, but now we have an intervening transitional taxon, Ara macao, the scarlet macaw (Figs. 4, 5), a brilliantly colored parrot.

Figure 1. Gastornis turns out to be a giant parrot sister in the chicken clade in the LRT.

Figure 1. Gastornis turns out to be a giant parrot sister in the chicken clade in the LRT.

But first….
In the last few days I added two extant birds to the LRT. The common house sparrow, Passer domesticus (Linneaus 1758; Figs. 1,2) nests between the chicken, Gallus, and the hoatzin, Opisthocomus in the large reptile tree (LRT, 1065 taxa; subset Fig. 7). This counters DNA studies (Hackett et al. 2008; Prum et al. 2015) which nested Passer in a very derived node in a very derived clade with the long-legged snake-eater, Cariama, at its base.

Usually
highly derived taxa with atypical traits nest at derived nodes, not basal nodes. Passer is the dictionary definition of a very typical, not highly derived bird.

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

Figure 2. Skeleton of the common house sparrow, Passer domestics.

 

So far,
the chicken/Gallus clade is primarily composed of herbivores/ grain/ seed eaters with a few insects and lizards thrown in. Since Gastornis appeared in the late Paleocene/early Eocene, that means sparrows, chickens and hoatzins also must have been part of this earliest radiation of Neognathae after the K-T extinction event.

Figure 2. Skull of Passer domestics in four views.

Figure 3. Skull of Passer domestics in four views.

The scarlet macaw,
Ara macao (Linneaus 1758, Figs. 3, 4) nests between Opisthocomus, the hoatzin and Gastornis (formerly Diatryma, Fig. 1), the giant Eocene herbivore formerly considered a predator of little Eocene 3-toed horses. Gastornis shares a remarkably long list of odd bird traits with Ara, including the separation of its orbit from its temporal fenestrae (Fig. 5). Wikipedia reports Gastornis originally was allied with cranes, but recent studies nest Gastornis with geese. Neither are as good a match for Gastornis, from head to toe (and palate, Figs. 5, 6), as parrots using the LRT as our guide.

Figure 3. Skeleton of Ara macao, the scarlet macaw. Note the skeleton has pedal digits 3 and 4 switched.

Figure 4. Skeleton of Ara macao, the scarlet macaw. Note the skeleton has pedal digits 3 and 4 switched.

Most of the skull elements in Ara are fused,
but the mandible, palatine and quadrate rotate beneath the skull like a parallelogram to lift the beak. Witmer and Rose 1991 compared the skull of Gastornis ( = Diatryma) with that of the parrot Amazona in their study of jaw mechanics, without making the phylogenetic connection.

Witmer and Rose 1991 reported,
“The morphology of the last group, parrots and finches, is similar to that of Diatryma.” They all nest together in the LRT. They also report, “Although the craniofacial hinge is not completely preserved in any known specimen, we suggest that Diatryma, like large parrots, probably had a diarthrodial craniofacial articulation.”

Figure 4. Skull of Ara macao with bones colored.

Figure 5. Skull of Ara macao with bones colored.

The first reconstructed palate of Gastornis
(Fig. 6) compares well with that of Ara macao (Fig. 5), including the massive palatine bones, the long slender pterygoids, the wide jugals and indented quadratojugals.

Figure 5. The palate of Gastronis/Diatryma uncrushed to match the uncrushed mandibles. Note the clear resemblance to the palate of the parrot, Ara macao in figure 4.

Figure 6. GIF movie, 4 frames of the palate of Gastronis/Diatryma uncrushed to match the uncrushed mandibles. Note the clear resemblance to the palate of the parrot, Ara macao in figure 4.

I know a lot of time and treasure
have gone into past DNA studies, but they do not and can not include extinct taxa. They do not replicate tree topologies when the phylogenetic distances are great. So they do not and can not produce gradual accumulations of derived traits to help us learn about bird evolution. It just doesn’t work on so many levels! So let’s keep DNA studies restricted to smaller clade studies.

Figure 7. Subset of the LRT showing the nesting of Passer and Ara, newly added taxa.

Figure 7. Subset of the LRT showing the nesting of Passer and Ara, newly added taxa.

Odd nestings
occur with DNA studies when phylogenetic distances are great:

  1. The plant-eating hoatzin nests at the base of the raptorial eagles, vultures and owls
  2. Raptorial seriemas and falcons nest with seed-eating parrots and passerines
  3. The nearly identical secretary bird, Sagittarius, and seriema, Cariama, nest far apart

Reasonable nestings
occur in DNA studies when phylogenetic distance are not great.

  1. The chicken. Gallus, nests with the ostrich, Struthio, and the tinamou, Crypturellius.
  2. The loon, Gavia, nests with the penguin, Spheniscus.

And you’ll only know the phylogenetic distances are great
after morphological studies – with fossils.

References
Agnolin F 2007. Brontornis burmeisteri Moreno & Mercerat, un Anseriformes (Aves) gigante del Mioceno Medio de Patagonia, Argentina. Revista del Museo Argentino de Ciencias Naturales, n.s. 9, 15-25
Andors AV 1992. Reappraisal of the Eocene ground bird Diatryma (Aves: Anserimorphae). Science Series Natural History Museum of Los Angeles County. 36: 109–125.
Hackett S et al. 2008. A phylogenetic study of birds reveals their evolutionary history. Science 320:1763–1768.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.
Mustoe GE, Tucker DS and Kemplin KL 2012. Giant Eocene bird footprints from northwest Washington, USA. Palaeontology. 55 (6): 1293–1305.
Prum RO et al. (6 co-authors) 2015. A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing. Nature doi:10.1038/nature15697
Witmer L and Rose K 1991. Biomechanics of the jaw apparatus of the gigantic Eocene bird Diatryma: Implications for diet and mode of life. Paleobiology. 17 (2): 95–120.

wiki/Gastornis
wiki/Sparrow
wiki/Scarlet_macaw

Click here for a video of a hatching and growing Hyacinth Macaw from Andy Hoo. Excellent. 100 days to fledge.
Reminds us that dinos are naked, not scaly. And they need parents to survive.

Dinosaur books

At one time
I wanted to write and illustrate a dinosaur book. I had an idea for one (Fig. 1) and was inspired by the writers and artists of the Dinosaur Renaissance. It took several years…

Figure 1. The cover of Giants, the book that launched my adult interest in dinosaurs, pterosaurs and everything inbetween.

Figure 1. The cover of Giants, the book that launched my adult interest in dinosaurs, pterosaurs and everything inbetween.

Then
I got a contract to do my first book. That begat another and another. The shelf life was no more than one year for any of them. None went to second editions, though several had foreign versions. Reviews were good. Libraries stocked them. Book signings were fun, when there was advanced publicity. Every so often there was a big or small check in the mail. Now Amazon keeps them alive, if just barely. Reviews are still good…

Nowadays
I would not want to write and illustrate another dinosaur book. New discoveries make at least part of the text and part of the depiction of its subjects obsolete, sometimes before shelf life is over. The amount of data needed to be covered is staggering. More pages mean the price the book rises out of the ability to pay for many potential readers. With book publication, there are no ‘do-overs’ or ‘updates.’ What’s done is done. And then there are always the nagging typos. There’s a lot of work involved. And it has to be polished perfect. Editors, working for publishers, have their say. So do collaborators, if any. You have to put your life on hold to get the thing done by deadline. And when it’s done, it sits on a bookstore shelf, just one more Christmas or birthday present vying for the consumer’s eye.

It’s much better to post blogs
and nurture growing websites, like ReptileEvolution.com. These can be updated at will in one’s spare time. There are no paper or printing costs. No ships and trucks to distribute them. No bookstores to deal with. No deadlines. News can be reviewed within a day, while it’s still fresh. Everyone in the world has free access to your work. They can focus in on what they really like and ignore the rest at no cost. And one more thing (quoting Steve Jobs) that books can’t provide: animation. There’s no profit in web publishing, but money was never the front and center issue.

Figure 2. Sample animation you’ll never see in a book. The Vienna specimen of Pterodactylus (wings folded). Animation opens the wings and legs to reveal the true shape of pterosaur wings, stretched between the elbow and wingtip with a short fuselage fillet extending from elbow to mid femur.

Even so
I’m glad I went through that book phase. It had its time and place. The process led me to interact with others of like interest. Some of them are PhDs. Others are fellow artists and writers. Everyone should have a hobby to keep in touch with the world and vice versa.

I was inspired to write this blog post
after seeing parts of Walking with Dinosaurs 3D on YouTube. Click here to see it. So much talent and effort went into this— truly outstanding visuals …but the dialog was horrible, as most others agree. And there are a few new dinosaur books out now, updating older dino books. I wish them all well. Someday, perhaps decades from now, those books will either be considered cherished classics or outdated, ready to be updated. It’s all good.

References
www.DavidPetersStudio.com/books
www.ReptileEvolution.com

Vegavis: Late Cretaceous, but not a member of the Euornithes

Clarke et al. 2005 brought us Vegavis iaai (MLP 93-I-3-1, MACN-PV 19.748; Late Cretaceous. 68 mya; Figs. 1, 2), a disarticulated partial fossil from Antarctica, which they considered a duck relative and the first definite member of the Euornithes (extant birds and kin) that lived before the K-T boundary.
Unfortunately I was not able to confirm this. The large reptile tree (LRT, 1064 tax, subset fig. 5) nests Vegavis as the proximal outgroup to Yanornis and the Ornithurae. It appears that mistakes were made by Clarke et al. which affected their matrix scores. If I made mistakes, I’d be happy to change them when better data comes along.
Figure 1. Vegavis in situ from Clarke et al. 2005. Colors added and used to create the reconstruction in figure 2. What they thought was the other humerus is instead a tibia still linked to the femur. What they thought was a long sacrum is instead the inside of the other humerus.

Figure 1. Vegavis in situ from Clarke et al. 2005. Colors added and used to create the reconstruction in figure 2. What they thought was the other humerus is instead a tibia still linked to the femur. What they thought was a long sacrum is instead the inside of the other humerus The original scale bars did not permit a good match between plate and counter plate.

From the Clarke et al. abstract: “Long-standing controversy surrounds the question of whether living bird lineages emerged after non-avian dinosaur extinction at the Cretaceous/Tertiary (K/T) boundary or whether these lineages coexisted with other dinosaurs and passed through this mass extinction event.”  “Here we identify a rare, partial skeleton from the Maastrichtian of Antarctica as the first Cretaceous fossil definitively placed within the extant bird radiation. Several phylogenetic analyses supported by independent histological data indicate that a new species, Vegavis iaai, is a part of Anseriformes (waterfowl) and is most closely related to Anatidae, which includes true ducks. A minimum of five divergences within Aves before the K/T bound- ary are inferred from the placement of Vegavis; at least duck, chicken and ratite bird relatives were coextant with non-avian dinosaurs.”
Figure x. Reconstruction of Vegavis at published size (print 300 dpi reduced to web 72 dpi).

Figure 2.5. Reconstruction of Vegavis at published size (print 300 dpi reduced to web 72 dpi).

Only a tiny reconstruction (Fig. 2.5) was provided by Clarke et al., so a larger one is provided here (Fig. 2) and it seems to be more crane- or ratite-like than duck-like, although the Eocene duck, Presbyornis (Fig. 3) does have a stork-like morphology. Clarke et al. conclude: Vegavis has different proportions from Presbyornis that are closer to other extant basal anseriform species [geese, screamers). Thus, there is further support that the wader proportions and the ecology used to diagnose Presbyorntihidae are derived for that particular anseriform lineage and not ancestral avian characteristics.” Not sure why they arrived at this conclusion because Vegavis appears to have  long-legged, stork- and ratite-like proportions (Fig. 2). This is a gracile bird.
Figure 2. Presbyornis (Eocene) and Anas (extant), a basal and modern duck.

Figure 3. Presbyornis (Eocene) and Anas (extant), a basal and modern duck.

Clarke et al. nest Vegavis and ducks with chickens, like Gallus, among basalmost Neognaths, derived from sisters to paleognath tinamous like Pseudocrypturus.
Figure 3. Reconstruction of the basal ornithuromorph bird, Archaeornithura with skull added. Feathers and ribs omitted. The length of the tail is hard to determine.

Figure 4. Reconstruction of the basal ornithuromorph bird, Archaeornithura with skull added. Feathers and ribs omitted. The length of the tail is hard to determine.

By contrast, the LRT nests ducks higher on the tree (Fig. 5), closer to long-legged predatory birds. Here Vegavis nests with other pre-Ornithurae Cretaceous birds, like Archaeornithura (Fig. 4), most of which have teeth, unfused metatarsals and gastralia. I found gastralia on the published photo of Vegavis. Unfused metatarsals were originally illustrated. The purported fused sacrum (yellow in figs 1, 2) is the same shape as a distal humerus. It appears to be a split humerus, internal view (Fig. 6). The other split ‘humerus’ appears to be a tibia still articulating with the distal femur. Unfused sacral vertebrae are identified above. Pedal digit 5 is not absent. No scattered cervicals are longer than tall. The ischium is shorter than the pubis, which has a small pubic foot. Apparently  all birds with shorter limbs evolved them by neotony. Ratite, flamingo and stork juveniles have shorter legs.
Figure 5. Subset of the LRT with the addition of Vegavis as a proximal outgroup to Yanornis and the Ornithurae.

Figure 5. Subset of the LRT with the addition of Vegavis as a proximal outgroup to Yanornis and the Ornithurae.

I’m interested only in getting things right. If you can provide better resolution images that support the original identifications, I will make changes to the data presented here. At present Vegavis is the result of a gradual accumulation of traits. It is transitional from birds with unfused sacrals and metatarsals to those with fused sacrals and metatarsals and no pedal digit 5 among several other traits.
References Clarke, JA, Tambussi CP, Noriega JI, Erickson GM and Ketcham RA 2005. Definitive fossil evidence for the extant avian radiation in the Cretaceous. Nature 433, 305–308. digimorph.org/specimens/Vegavis_iaai/ wiki/Vegavis

Gansus: an Early Cretaceous volant basal hesperornithid

Figure 1. Gansus as originally reconstructed and with corrections indicated by the fossils.

Figure 1. Gansus as originally reconstructed and with corrections indicated by the fossils. 2 frames every 5 seconds. Note the actual shape of the coracoid fossils compared to the illustrated version. Note the long pedal digit 4 and the long posterior ilium.

Gansus yumenensis (Early Cretaceous; Hou and Liu 1984, You et al. 2006) is known from several fossils, none of them complete and none of them including the skull, mandibles or anterior neck. Both You et al. and the large reptile tree (LRT, 1063 taxa) nest Gansus between Hesperornis and Ichthyornis among the Mesozoic toothed birds. The long posterior ilium and long pedal digit 4 are the first traits shared with Hesperornis, appearing some 35 million years later. 

The LRT used far fewer bird traits
than did You et al. And I never observed the fossil firsthand. Nevertheless the LRT was able to confirm the nesting of Gansus in You et. al.

References
Hou L and Liu Z 1984. A new fossil bird from Lower Cretaceous of Gansu and early evolution of birds. Sci. Sin. Ser. B. 27:1296−1302.
Li Y et al. (5 co-authors) 2011. New material of Gansus and a discussion on its habit.  Vertebrata PalAsiatica 49:435–445.
You et al. (12 co-authors) 2006.
A nearly modern amphibious bird from the Early Cretaceous of Northwestern China. Science 312:1640–1643.

wiki/Gansus

 

The pre or post K-T origin of extant birds (Neornithes)

Today
we’re going to add Apsaravis (Norell and Clarke 2001, Late Cretaceous, Figs. 1–3) to the large reptile tree.

Figure 1. Yanornis, Apsaravis and Pseudocrypturus to scale. The origin of all extant birds starts here.

Figure 1. This is not a phylogenetic order. Apsaravis is an offshoot. Here are Yanornis (Early Cretaceous), Apsaravis (Late Cretaceous) and Pseudocrypturus (early Eocene) to scale. The origin of all extant birds starts here. We’re still missing fossils in the small morphological but large chronological gap between Yanornis and Pseudocrtypturus (Late Cretaceous + Paleocene), But in the meantime, Paleocene birds show great variation (see yesterday’s post).

Norell and Clarke 2001
introduced us to Apsaraviis (Fig. 1), a Late Cretaceous volant and probably toothed bird from Mongolia. Clarke and Norell 2001 nested Apasaravis between Hesperornis and Ichthyornis + Aves (Crypturellus, a genus of extant tinamous).

Clarke and Norell 2002 reported:
“Phylogenetic placement of Apsaravis ukhaana as the sister taxon of Hesperornithes + Aves resulted from analysis of 202 characters scored for 17 avialan ingroup taxa.”

Largely in agreement with both original papers,
the large reptile tree (LRT, 1063 taxa) nests Apsaravis with Ichthyornis and Hesperornis. Yanornis martini (Zhou and Zhang 2001) nested basal to all three and basal to Pseudocrypturus, at the base of extant birds. Neither Norell and Clarke 2001 nor Clarke and Norell 2002 mention Yanornis in their papers that came out at about the same time as the publication of Yanornis. Note: The LRT did not employ 202 bird traits, but 231 generalized traits, only a few of which were needed to nest Apsaravis exactly where Norell and Clarke did (sans Yanornis).

This is why taxa are more important than characters.
You need taxa. They are the puzzle pieces that create the big picture. You need a long list of characters, but you don’t need a really long list of characters if the long list is sufficient to lump and separate all the pertinent taxa, even if does so just barely.

Figure 1. Apsaravis in situ. Here the poster end of the scapulae hide among the ribs, but a very simple case of DGS clarifies the situation.

Figure 1. Apsaravis in situ I’m ventral exposure from Norell and Clarke 2001. Here the posterior end of the scapulae hide among the ribs, but a very simple coloring (DGS) clarifies the situation. See Figure 3 for a reconstruction of these elements.

Sometimes reconstructions are presented rough
(Fig. 3) which keeps the fidelity of the original tracing at the expense of creating a clunky in vivo pose.

Figure 3. Apsaravis reconstructed from original drawings in Norell and Clarke 2001.

Figure 3. Apsaravis reconstructed from original drawings in Norell and Clarke 2001. The rostrum was probably long, as in Ichthyornis.

Wikipedia reports:

“Apsaravis is important in avian paleontology. It has provided evidence that is directly relevant to at least four issues:”

  1. Evidence against a clade Sauriurae, which includes Archaeopteryx, Confuciusornis and Enantiornithes and is separate from modern birds. The LRT nests several Solnhofen birds (= in this sense Archaeopteryx) at the bases of all the higher bird clades, including modern birds. Adding more Solnhofen birds needs to be done in all future analyses. The LRT does not recover the clade Sauriurae separate from modern birds.
  2. Apsaravis erodes the monophyly of the clade Enantiornithes. The LRT supports the monophyly of the Enantiornithes with or without Apsaravis.
  3. Found in desert dry sediments Apsaravis proves that not all early members of Ornithurae (extant birds + Ichthyornis + Hesperornis) were shore birds. True. But we know that volant birds can fly and die anywhere. Additionally deserts often include oases.
  4. Asparavis is the most basal bird with an extensor process, a bony projection medial to metacarpal 1. This automates extension of the manus during extension of the forelimb. Here that extensor process is homologous to digit 0. I thought the non-rotating radius bone, working like a parallelogram, was responsible for automatic extension of the manus during forelimb extension (as in bats and pterosaurs). Let’s compromise and say all the parts work together.

Today’s examination of Apsaravis
brings up a similar genus, Ambiortus (Kurochkin 1985; Late Cretaceous). Unfortunately it is only known from an incomplete anterior torso and a few feathers.

And then, there’s Gansus.
Gansus (Hou & Liu 1984, You et al. 2006) is now known from several incomplete skeletons, all lacking a skull. It has been described as an Early Cretaceous (Aptian-Albian), duck-like ornithurine. You et al. nested it between Hesperornis and Ichthyornis, so, according to their studies, it is not a member of the clade of modern toothless birds, the Neornithes. That is confirmed by a recent reconstruction and nesting in the LRT that nests Gansus as a basal hesperornithid. We’ll look at that taxon in more detail soon.

We’re still missing Late Cretaceous and Paleocene fossils
fromn the small morphological gap, but large chronological gap between Yanornis and Pseudocrtypturus. In the meantime, Paleocene birds show great taxonomic variation (see yesterday’s post). So my guess/prediction is we’re going to someday see more pre-Tertiary euornithine birds discovered that survive the K-T event and continue to radiate in the Paleocene. Pseudocrtypturus changed relatively little during that time, resembling extant tinamous.

References
Norell MA and Clarke JA 2001. Fossil that fills a critical gap in avian evolution. Nature 409:181–184.
Clarke JA and Norell MA 2002. The morphology and phylogenetic position of Apsaravis ukhaana from the Late Cretaceous of Mongolia. American Museum Novitates 3387:46 pp.

wiki/Apsaravis

Pseudocrypturus: close to the base of all living birds

Pseudocrypturus cercanaxius
(Houde 1988; Early Eocene) was originally considered a northern hemisphere ancestor to ratites (like the ostrich, Struthio). Today primitive flightless birds are chiefly restricted to the southern hemisphere. But note #11 below.

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

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

Then again,
it could be that early birds did start in the South at the K-T boundary, finding refuge near the antipodes from the Yucatan crater site (like China), and had migrated back around the world and back to the North during the Paleocene (66–56 mya). We looked at the record of Paleocene birds earlier here, (Fig. 1) but we didn’t talk about what sort of birds these were. Here they are again with a few more details.

  1. WaimanuNew Zealand sphenisciform close to penguins
  2. AustralornisNew Zealand precursor to living sea bird families
  3. QianshanornisChina cariamiform close to Cariama
  4. QinornisChina closer to Mesozoic birds (divisions still visible in the metatarsus)
  5. LithornisN. America lithornithiform close to Pseudocrypturus
  6. OgygoptynxN. America strigiform (owl)
  7. NovacaesarealaN. America procellariform? (sea bird) close to Torotix
  8. FissuravisEurope lithornithiform close to Pseudocrypturus
  9. BerruornisEurope strigiform close to Bubo, the owl
  10. Gastornis Europe giant anseriform (LRT nests it with the herbivore hoatzin, Opisthocomus)
  11. Remiornis Europe ratite close to Rhea
  12. Lithoptila N. Africa prophaethontid (sea bird) close to Phaethon
  13. Paleopsilopterus – S. America giant cariamiform close to Phorusrhacos
  14. ItaboravisS. America cariamiform close to Cariama
  15. DiogenornisS. America ratite close to Rhea
  16. This list is not complete

Ornithologists generally agree
that most major bird families diversified or were present in the Paleocene. Given the variety of birds already known, though scarce, this appears to be valid.

Since ratites are basal to extant birds,
and Pseudocrypturus is basal to ratites (paleognaths), Pseudocrypturus may be similar to the ancestor of all extant birds, perhaps a ‘living fossil’ in the early Eocene. Given its basal position in the LRT, perhaps something very much like it was one of the few survivors of the K-T extinction event.

Figure 1. My introduction to Pseudocrypturus was as this drawing in Carroll 1988. Here a DGS tracing of the skull is compared to earlier drawings.

Figure 2. My introduction to Pseudocrypturus was as this drawing in Carroll 1988. Here a DGS tracing of the skull is compared to earlier drawings.

It’s notable
that Pseudocrypturus had long legs. Early ducks, like Presbyornis, and basal raptors, like  Sagittarius, also had long legs. Evidence appears to be building that this was the primitive condition for the clade of living birds.

Figure 2. Pseudocrypturus skull in plate and counter plate plus color tracings and a reconstruction. Note the tiny postorbital. It's on its way out.

Figure 3. Pseudocrypturus skull in plate and counter plate plus color tracings and a reconstruction. Note the tiny postorbital. It’s on its way out.

In the large reptile tree
(LRT, 1059 taxa) Pseudocrypturus nests where Houde 1986 nested it.

Figure 1. Extant birds and their kin. Hummingbirds and their kin and penguins and their kin have been added using the same list of 230 or so characters that have served to nest reptiles, including mammals.

Figure 1. Extant birds and their kin. Hummingbirds and their kin and penguins and their kin have been added using the same list of 230 or so characters that have served to nest reptiles, including mammals.

Good to again confirm
earlier nestings. Not sure how many or which birds to consider next.

References
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.

wiki/Pseudocrypturus

Hummingbird and penguin added to the LRT

Updated September 16, 2017 with a new reconstruction of the skull of Eocypselus.

Today we add
Archilochus (ruby-throated hummingbird), Eocypselus (basal to hummingbirds and swifts), Aptenodytes (emperor penguin) and Gavia (loon or diver (Figs. 1–5) to the large reptile tree (LRT, 1059 taxa). I’m happy to report they nest right where everyone else nests them (Fig. 1), given the very limited number of modern birds in the LRT.

Figure 1. Extant birds and their kin. Hummingbirds and their kin and penguins and their kin have been added using the same list of 230 or so characters that have served to nest reptiles, including mammals.

Figure 1. Extant birds and their kin. Hummingbirds and their kin and penguins and their kin have been added using the same list of 231 characters that have served to nest reptiles, including mammals.

The LRT
is somehow still working as four birds are added, lumped and separated as shown above.

Figure 2. Emperor penguin (Aptenodytes) skeleton. Note the large scapula and short femur.

Figure 2. Emperor penguin (Aptenodytes) skeleton. Note the large scapula and short femur.

Aptenodytes forsteri (Miller 1778; 1.2m tall) the extant emperor penguin is considered a basal penguin, having split from the others about 40 mya. The large scapula anchored strong wing muscles for underwater flying. Note the C-shaped furcula and large patella. Neither are traits listed by the LRT, but fall into place naturally due to the rest of the traits.

FIgure 4. Note the extremely large patella on this Gavia skeleton.

FIgure 4. Note the extremely large patella on this Gavia skeleton.

Gavia stellata (Forster 1788) the extant red-thrated diver Loon toe lobes are connected by webbing. Pedal digit 1 is a vestige. Gavia is similar to Cretaceous era Hesperornis, by convergence. Hackett et al. 2008 nested loons with penguins, and this is confirmed in the LRT. Both share a very short femur among other traits. Note the C-shaped furcula and very large patella (orange).

Figure 3. Ruby-throated hummingbird (Archilochus) skeleton.

Figure 3. Ruby-throated hummingbird (Archilochus) skeleton. Image courtesy of Digimorph.org and used with permission. Colors added.

Archilochus coubris (L. Reichenbach, 1854) is the extant ruby-throated hummingbird. Among the smallest of birds, hummingbirds are only found in the Americas. Their wings hum because they flap so rapidly, approximately 50x/second. They have the highest metabolism during the day, but at night they experience torpor to conserve energy. They survive on nectar from flowers, with which they co-evolved. Hummingbirds are related to swifts and are known form 30-million-year-old fossils. Note the furcula is not C-shaped in lateral view.

Figure 4. Reconstruction of Eocypelus. The pelvis is preserved in ventral view, so is difficult to ascertain in lateral view, but it probably looked very much like that of most other similar birds.

Figure 4. Reconstruction of Eocypelus. The pelvis is preserved in ventral view, so is difficult to ascertain in lateral view, but it probably looked very much like that of most other similar birds.

Eocypselus rowei (Mayr 2003, Ksepka et al. 2013; Eocene, 50 mya) was originally considered a swift and hummingbird ancestor. Eocypselus rowei had a stout humerus, but not so stout as either a swift or hummingbird, both of which were relatively 2/3 the length and 1/3 deeper. Likewise in the swift and hummingbird the radius/ulna is about 2/3 of the length in Eocypselus rowei. The manus of the swift and hummingbird is much longer than the combined length of the ulna and humerus, but not so in the more generalized and primitive Eocypselus rowei. Like Archilochus Eocypselus had a long narrow rostrum. Like Archilochus the sternum was long and deep.

Eocypselus vincenti (Harrison 1984, Mayr 2010, Fig. 5) is a congeneric specimen from the Early Eocene of Europe.

References
Deguine, J-C 1974. Emperor Penguin: Bird of the Antarctic. The Stephen Greene Press, Vermont.
Forster JR 1788. Enchiridion historiae naturali inserviens, quo termini et delineationes ad avium, piscium, insectorum et plantarum adumbrationes intelligendas et concinnandas, secundum methodum systematis Linnaeani continentur. – pp. 1-224. Halae. (Hemmerde & Schwetschke).
Hackett S et al. 2008. A phylogenetic study of birds reveals their evolutionary history. Science 320:1763–1768.
Ksepka DT, Clarke JA, Nesbitt SJ, Kulp FB and Grande L. 2013. Fossil evidence of wing shape in a stem relative of swifts and hummingbirds (Aves, Pan-Apodiformes). Proceedings of the Royal Society B: Biological Sciences 280 (1761): 20130580. doi:10.1098/rspb.2013.0580. Supplementary materials here.
Mayr G 2003. Phylogeny of early Tertiary swifts and hummingbirds (Aves: Apodiformes). The Auk 120(1):145–151, 2003. online
Mayr G 2009. Paleogene Fossil Birds (online) Springer.
Mayr G 2010. Reappraisal of Eocypselus—a stem group apodiform from the early Eocene of Northern Europe. Palaeobiodiversity and Palaeoenvironments 90(4): 395-403.
Reichenbach 1854, L. Aufzählung der Colibris oder Trochilideen in ihrer wahren natiirlichen Verwandtschaft, nebst Schlüssel ihrer Synonymik. Extra., marz, 1–54. besondere Beilage: 1–24.(Enumeration of the colibris or trochilides in their true natural relationship, together with the keys of their synonymy. Extra., Malt, 1-54. Special supplement: 1–24.)

 

wiki/Aptenodytes
wiki/Gavia