Jurassic birds took off from the ground – SVP abstracts 2016

Everyone knows:
Ground up hypothesis – 

implies and includes flapping, always has. Birds flap, always have, at least since the elongation and locking down of the coracoid in ancestral troodontids.

Trees down hypothesis –
has always implied gliding. Gliders don’t flap, never have.

But
baby birds dropping out of trees always flap. It’s what they do. But that fact is often ignored in bird origin videos.

And, as everyone knows by now…
young birds with pre-violant wings flap them like crazy when climbing bipedally — even vertical tree trunks… also something several animated bird origin videos ignore, perhaps because of one glaring opposite extant example: the young wet hoatzin that struggles to climb with all four limbs.

With that preamble…Habib et al. 2016 provide us
a hypothesis on the origin of bird flight that appears to ignore trees and experimental work with pre-volant birds and goes straight to take-off from flat ground. Is that okay?

From the abstract:
“Many small non-avian theropods possessed well-developed feathered forelimbs, but questions remain of when powered flight evolved and whether it occured more than once within Maniraptora. Here, using a first principles modeling approach, we explore these questions and attempt to determine in which taxa takeoff and powered flight was possible. Takeoff is here defined as a combination of both the hindlimb driving the ballistic launch phase, and the wing-based propulsion (climb out). [1]

“Microraptor, Rahonavis, [2] and all avian specimens generated sufficient velocity during leaping or running for takeoff. We re-ran our analysis factoring in life history changes that can alter the flight capability in extant avians, such as egg retention and molting, to examine how these would influence take off capacity. Of the two, molting shows the most significant effects.

“When these results are coupled with work detailing the lack of arboreal features among non-avian maniraptorans and early birds, they support the hypothesis that birds achieved flight without a gliding intermediary step, something perhaps unique among volant tetrapod clades.” [3] [4] [5]

Figure 2. Cosesaurus running and flapping - slow.

Figure 1. Cosesaurus running and flapping – slow.

Notes

  1. Interesting that Habib et al. ignore the presence of trees, which are key to Dial’s hypothesis (updated in Heers et al. 2016)  and opts to go straight from ground to air. That kind of ignores key work, doesn’t it? You might recall that Dr. Habib became famous as the author of the infamous but popular forelimb quad launch hypothesis for pterosaurs.
  2.  Microraptor and Rahonavis are NOT in the lineage of birds in the LRT, but both show how widespread long feathered wings were in Theropoda. The former has elongate coracoids by convergence. The latter does not preserve coracoids, fingers or feathers, but does have the long forearm that might imply bird-like proportions for missing bones… or not.
  3. Apparently Habib et al. assume that pterosaurs and bats originated as gliders when present largely ignored evidence indicates exactly the opposite. Cosesaurus (Fig. 1) was a pterosaur precursor with elongate coracoids, unable to fly, but able to flap. Bats rarely glide, so it is unlikely that they did so primitively. Lacking coracoids, bats employ elongate clavicles to anchor flight muscles.
  4. Okay, so remember the preamble (above) about gliding and trees. When Habib et al. bring up ‘a gliding intermediary step‘, they are implying the presence of trees (high places) in competing and validated-by-experiment hypotheses for the origin of bird flight  — which they are ignoring. They also ignore the fact that baby birds don’t glide when they fall out of trees. They flap like their lives depend upon it. I find those omissions odd, but its not the first time pertinent work has been ignored in paleontology.
  5. In the LRT Xiaotingia (Fig. 2) is the most primitive bird-like troodontid to have elongate coracoids and so may have been the first flapper in the lineage.
Figure 1. Xiaotingia with new pectoral interpretation. See figure 3 for new tracing.

Figure 2. Xiaotingia with new pectoral interpretation.

References
Habib M, Dececchi A, Dufaault D and Larsson HC 2016. Up, up and away: terrestrial launching in theropods. Abstract from the 2016 meeting of the Society of Vertebrate Paleontology.
Heers AM, Baier DB, Jackson BE & Dial  KP 2016. 
Flapping before Flight: High Resolution, Three-Dimensional Skeletal Kinematics of Wings and Legs during Avian Development. PLoS ONE 11(4): e0153446. doi:10.1371/journal.pone.0153446
http: // journals.plos.org/plosone/article?id=10.1371/journal.pone.0153446

YouTube video showing birds running up tree trunks while flapping with nonviolent wings

ScienceNews online promo.

The geologically oldest Archaeopteryx (#12)

Updated November 10, 2016 with higher resolution images of the specimen. The new data moved the taxon over by one node. 

Not published yet in any academic journal,
but making the news in the popular press in Germany to promote a dinosaur museum (links below) is the geologically oldest Archaeopteryx specimen (no museum number, privately owned?). Found by a private collector in 2010, the specimen has been declared a Cultural Monument of National Significance. It is 153 million years old, several hundred thousand years older than the prior oldest Archaeopteryx. It is currently on  display at a new museum, Dinosaurier-Freiluftmuseum Altmühltal in Germany, about 10 kilometers from where the fossil was found.

Figure 1. The new oldest Archaeopteryx in situ with color tracings of bones.

Figure 1. The new oldest Archaeopteryx in situ with color tracings of bones. The ilium has been displaced to the posterior gastralia, or is absent. I cannot tell with this resolution.

Figure 1b. Archaeopteryx 12 in higher resolution.

Figure 1b. Archaeopteryx 12 in higher resolution.

So is it also the most primitive Archaeopteryx?
No. But it nests as the most primitive scansioropterygid bird. As we learned earlier, the Solnhofen birds formerly all considered members of the genus Archaeopteryx (some of been subsequently recognized by certain authors as distinct genera) include a variety of sizes, shapes and morphologies (Fig. 3) that lump and separate them on the large reptile tree. The present specimen has been tested, but will not be added to the LRT until it has a museum number or has been academically published (both seem unlikely given the private status). Given the additional publicity the specimen is now in the LRT.

The fossil is wonderfully complete and articulated
and brings the total number of Solnhofen birds to an even dozen.

This just in
Ben Creisler reports, “The fossil specimen was originally found in 2010 in fragmented condition and took great effort to prepare and piece together as it now appears.”

Figure 2. Reconstruction of the geologically oldest Archaeopteryx, now nesting at the base of the Scansoriopterygidae.   Note the large premaxillary teeth and short snout on a relatively small skull.

Figure 2. Reconstruction of the geologically oldest Archaeopteryx, now nesting at the base of the Scansoriopterygidae. Note the large premaxillary teeth and short snout on a relatively small skull.

Compared to other Archaeopteryx specimens
you can see the new one is among the smallest (Fig. 3) and has a distinct anatomy.

Figure 2. Several Archaeopteryx specimens. The geologically oldest one, (at bottom) is among the smallest and most derived, indicating an earlier radiation than the Solnhofen formation.

Figure 2. Several Archaeopteryx specimens. The geologically oldest one, (at bottom) is among the smallest and most derived, indicating an earlier radiation than the Solnhofen formation.

References
Spektakulaerer-Fund-kommt-in-Ausstellung-article
originalskelett-eines-archaeopteryx-zu-sehen.html
auf-zum-archaeopteryx

Website

Jeholornis nests within current Archaeopteryx specimens

That Jeholornis nests
as the Chinese Archaeopteryx comes as no surprise. Jeholornis was always considered a close relative of Archaeopteryx. The key difference here (Fig. 1) in this subset of the large reptile tree is that earlier we nested several specimens of Archaeopteryx at the bases of all the later major bird clades (Fig. 1). That’s an unorthodox hypothesis seeking acceptance and widespread practice.

Figure 1. Subset of the large reptile tree focusing on birds, not including bird-like taxa in more basal clades. Not the nesting of Jeholornis within the clade of Solnhofen birds, too often lumped under a single taxon, Archaeopteryx.

Figure 1. Subset of the large reptile tree focusing on birds, not including bird-like taxa in more basal clades. Not the nesting of Jeholornis within the clade of Solnhofen birds, too often lumped under a single taxon, Archaeopteryx.

Now we can nest Jeholornis
with between certain specimens of Archaeopteryx and not others.

  1. Archaeopteryx siemensii (Thermopolis specimen) – basalmost Aves
  2. Archaeopteryx siemensii  (Berlin specimen)- basal Enantiornithes
  3. Archaeopteryx lithographica  (London specimen- holotype)- basal Enantiornithes
  4. Archaeopteryx bavarica  – basal Scansioropterygidae
  5. Jeholornis prima – basalmost Ornithurae
  6. Archaeopteryx [Jurapteryx] recurva (Eichstaett specimen) basal Ornithurae (including extant birds)
  7. Archaeopteryx [Welllnhoferia] grandis (Solhnhofen specimen) – Confuciusornithiformes (within Ornithurae)

The nesting of Jeholornis within the clade of basal Solnhofen birds solves many problems.

Jeholornis is the only long-tailed avian genus from China.
Zhou and Zhang 2002 report, “This bird is distinctively different from other known birds of the Early Cretaceous period in retaining a long skeletal tail with unexpected elongated prezygopophyses and chevrons, resembling that of dromaeosaurids, providing a further link between birds and non-avian theropods.”

O’Connor et al. 2011 report, “The Early Cretaceous long bony-tailed bird Jeholornis prima displays characters both more basal than Archaeopteryx and more derived, exemplifying the mosaic distribution of advanced avian features that characterises early avian evolution and obfuscates attempts to understand early bird relationships.”

Confusion over the nesting
of Jeholornis has probably resulted from taxon exclusion. Virtually all prior studies included only one Archaeopteryx as a taxon. Which one? I don’t know. More taxa of Solnhofen birds need to be added.

Contra Zhou and Zhang 2002
in the large reptile tree, birds are not derived from dromaeosaurids, but from increasingly bird-like troodontids like Sinornithoides, Aurornis, Anchiornis, Eosinosauropteryx, and Xiaotingia.

Figure 2. The holotype of Jeholornis skull traced and reconstructed using DGS methods. Here maxillary teeth and the premaxilla were identified. Colorizing helps identify bones more easily than simple black outlines.

Figure 2. The holotype of Jeholornis skull traced and reconstructed using DGS methods. Here maxillary teeth and the premaxilla were identified. Colorizing helps identify bones more easily than simple black outlines. If you see any errors, pleas call them to my attention. The postorbital is reconstructed with a process entering the orbit. This is an unrestored break, not a real process.

Maxillary teeth
Zhou and Zhang 2002 report, “The maxilla is reduced and does not bear any teeth.” Using Photoshop and the DGS method, I was able to find left maxillary teeth in the holotype of Jeholornis (Fig. 2). The right maxillary teeth may be scattered or buried. The premaxilla (with teeth) was found to be jammed up against the other rostral bones.

Flapping
Zhou and Zhang 2002 report, “The  derived features of the pectoral girdle of Jeholornis such as a strut-like coracoid and the well-developed carpal trochlea of the carpometacarpus, suggest the capability of powerful flight.”  I agree.

Also note
Sapeornis nests within the Ornithurae grade with this list of taxa as other Sapeornithiformes are not currently listed. We’ll look at the skull tomorrow.

Jeholornis is not the first archaeopteryx-like bird from China.
We also have the Liaoning embryo, which nests with the holotype of Archaeopteryx, the London specimen (Fig. 1). Basically, only the relatively large skull, large orbit and small, gracile cervicals of the embryo, distinguish the two taxa, but then those are juvenile traits in birds that change allometrically during ontogeny.

The Jehol Group
(according to O’Connor et al. 2011) “consists of three formations, namely the Dabeigou, Yixian and Jiufotang (Zhou 2006), which record primarily lake and volcanic deposits that are approximately 131 to 120 Ma old (He et al. 2004, 2006; Yang et al. 2007; Zhu et al. 2007). The youngest formation of the Jehol Group, the Jiufotang Formation, preserves the most diverse Mesozoic avifauna known in the world, with long-tailed birds most closely related to Archaeopteryx living alongside the earliest ornithurines (Zhou 2006).”

Lumping or splitting
Some paleontologists lump all Archaeopteryx specimens together. Phylogenetic analysis (Fig. 1) indicates they should be split apart. That needs to start happening in bird studies. I’m happy to support it and promote it.

In similar fashion
earlier I disagreed with those who lump all Rhamphorhynchus specimens together. Phylogenetic analysis is able to split them apart and even find a juvenile of a giant. This juvenile is the size of smaller adult species, hence the confusion.

For those still insisting that the large reptile tree needs more ‘key’ characters
let me remind you that the currently employed list of non-theropod, non-bird specific character traits is doing a better job of lumping and splitting 645 taxa with the current list of 228 traits, (151 parsimony informative traits in theropods), even while testing close matches, like Jeholornis, to current taxa like the several Archaeopteryx specimens. We have a saying here in the USA: “If it ain’t broke, don’t fix it.”

References
O’Connor JK, Sun C-K, Xu X, Wang X-L and Zhou Z-H 2011. A new species of Jeholornis with complete caudal integument. Historical Biology iFirst article, 2011, 1–13.
Zhou Z-H and Zhang F-C 2002. A long-tailed, seed-eating bird from
the Early Cretaceous of China. Nature 418:405-409.

What makes a bird a bird? Everyone knows, it’s not feathers any more…)

The line between birds and theropod dinosaurs
has become increasingly fuzzy now that so many non-birds have feathers and other former bird-only traits.

This is a good sign
that evolutionary theory embraces: small changes and a gradual accumulation of traits in derived taxa.

Ultimately
it may come down to a single defining trait (like mammary glands in mammals, or alternatively a squamosal/dentary jaw joint when soft tissue is missing) when you have lots of taxa near the base of a new major clade. So what is that trait? Or what are those traits as recovered by the large reptile tree?

The basal bird and its proximal outgroup
At present the last common ancestor of all extant birds, scansoriopterygids and enantiornithes in the large reptile tree. is the Thermopolis specimen of Archaeopteryx (Fig. 1). The original authors (Mayr et al. 2007; Rauhut 2013) did not employ a phylogenetic analysis, so perhaps did not realize what they had.

For now
the pre-bird theropod, Eosinopteryx (Fig.1) nests just basal to the basal bird theropod, Archaeopteryx. You might find it interesting to see which traits differentiate the latter from the former in the large reptile tree. This list, short as it is, is by no means complete. It simply reflects the general characters used for all reptiles in the large reptile tree.

Figure 1. Eosinopteryx, a pre-bird, compared to Archaeopteryx, a basal bird to scale. Click to enlarge.

Figure 1. Eosinopteryx, a pre-bird, compared to Archaeopteryx, a basal bird to scale. Click to enlarge.

Archaeopteryx (Thermopolis) novelties vs. Eosinopteryx

  1. Frontal/parietal suture straight and > than frontal/nasal suture
  2. Metacarpals 2-3 subequal
  3. Pubis and ischium oriented posteriorly (convergent with some deinonychosaurs)
  4. Pedal 4 subequal to metatarsal 4  (convergent with some deinonychosaurs)
  5. Pedal 2.1 not > p2.2
  6. Metatarsal 5 shorter than pedal digit 5 (all vestigial, of course)
Figure 2. The coracoid of the Thermopolis specimen is not as elongate as in the more derived taxa. It is just barely not a disc. Thus, this basal taxon was not quite the flapper as the other Solnhofen birds.

Figure 2. The coracoid of the Thermopolis specimen is not as elongate as in the more derived taxa. It is just barely not a disc. Thus, this basal taxon was not quite the flapper as the other Solnhofen birds.

Unfortunately
none of these traits are unique to the bird clade.

I thought, perhaps
that an elongate and locked down coracoid (the key to the origin of flapping) would prove to be present in all basal birds. Such a coracoid is indeed present in other specimens of Solnhofen birds, but not in the Thermopolis specimen (Fig. 2), the basalmost example. 

So what we are seeing
in these six Solnhofen birds are discrete steps in the evolution of the flapping behavior, necessary for creating thrust and ultimately flight, as in many living birds. Just as in Late Jurassic pterosaurs, the island/lagoon environment of Solnhofen was as powerful an agent as the Galapagos islands at splitting basal birds into various clades.

From the Mayr et al. abstract on the Thermopolis specimen:
“We describe the tenth skeletal specimen of the Upper Jurassic Archaeopterygidae. The almost complete and well-preserved skeleton is assigned to  Archaeopteryx siemensii
 Dames, 1897 and provides significant new information on the osteology of the Archaeopterygidae. As is evident from the new specimen, the palatine of Archaeopteryx
 was tetra-radiate as in non-avian theropods, and not triradiate as in other avians. Also with respect to the position of the ectopterygoid, the data obtained from the new specimen lead to a revision of a previous reconstruction of the palate of Archaeopteryx. The morphology of the coracoid and that of the proximal tarsals is, for the first time, clearly visible in the new specimen. The new specimen demonstrates the presence of a hyperextendible second toe in Archaeopteryx*.  This feature is otherwise known only from the basal avian Rahonavis and deinonychosaurs (Dromaeosauridae and Troodontidae), and its presence in Archaeopteryx provides additional evidence for a close relationship between deinonychosaurs and avians**. The new specimen also shows that the first toe of Archaeopteryx was not fully reversed but spread medially, supporting previous  assumptions that Archaeopteryx was only facultatively arboreal*. Finally,we comment on the taxonomic composition of the Archaeopterygidae and conclude that Archaeopteryx bavarica Wellnhofer, 1993 is likely to be a junior synonym of  A. siemensii****, and Wellnhoferia grandis Elzanowski, 2001 a junior synonym of  A. lithographica***** von Meyer, 1861.”

* Actually not as prominent as in deinonychosaurs. Such a toe works just as well at climbing tree trunks as climbing dinosaur flanks.

**This may be a convergence as the two clades are separated by taxa without a hyper extensible pedal 2.

*** Perhaps facultatively able to perch, but arboreality would have been a precursor behavior.

**** These two are sisters in the large reptile tree.

***** These two are not sisters.

Other traits in the Theromopolis specimen 
visible in Figure 1 not present in the large reptile tree include the following:

  1. Smaller antorbital fenestra
  2. Longer attenuate tail
  3. Slightly narrower coracoids
  4. Slightly larger forelimb
  5. Bowed gap between ulna and radius
  6. More gracile pubis, posteriorly oriented
Figure 3. Archaeopteryx Thermopolis pedal digit 2 (in pink). Pedal 2.2 was capable of hyperextension (see figure 4).

Figure 3. Archaeopteryx Thermopolis pedal digit 2 (in pink). Pedal 2.2 was capable of hyperextension (see figure 4).

Mayr et al. looked at pedal digit 2
and noticed it was capable of hyperextension (Fig. 3). They likened it to pedal digit 2 in deinonychosaurs (Fig. 4) which is famous for its ability to elevate the ‘killer claw’.

Figure 4. Deinonychus with elevated pedal digit 2 demonstrating hyperextension.

Figure 4. Deinonychus with elevated pedal digit 2 demonstrating hyperextension.

The large reptile tree
does not nest birds with deinonychosaurs. Rather Xiaotingia and Eosinopteryx nest between these clades. And Xiaotingia also has a similar pedal 2.1 (Fig. 5).

Figure 5. Pedal digit 2 in Xiaotiniga shows the ability to hyperextend pedal 2.2.

Figure 5. Pedal digit 2 in Xiaotiniga also shows the ability to hyperextend pedal 2.2.

On a final note:
Mayr et al. (2007) report four premaxillary teeth in the Thermopolis specimen. I think they might have missed counting the anteriormost premaxillary tooth (Fig. 6) bringing the total to five.

Figure 6. Archaeopteryx, Thermopolis specimen, premaxilla with five teeth, not four, identified here.

Figure 6. Archaeopteryx, Thermopolis specimen, premaxilla with five teeth, not four, identified here.

References
Rauhut OWM 2013. New observations on the skull of Archaeopteryx. Paläontologische Zeitschrift 88(2)211-221.
Mayr G, Pohl, B, Hartmann S and Peters DS 2007. The tenth skeletal specimen of Archaeopteryx. Zoological Journal of the Linnean Society 149:97-116.

Archaeopteryx bavarica: the Munich specimen, is a basal scansoriopterygid

Earlier we looked at the nesting of other Archaeopteryx specimens. Here we’ll add a sixth, the Munich specimen, Archaeopteryx bavarica (Wellnhofer 1993, Figs. 1-4).

Figure 1. The Munich specimen of Archaeopteryx bavarica nests at the base of the scansoropterygids. It has a long third finger and other traits.

Figure 1. The Munich specimen of Archaeopteryx bavarica nests at the base of the scansoropterygids. It has a long third finger and other traits. Click to enlarge.

A. bavarica
is largely complete, lacking only a maxilla and a few rostral bones. What sets this specimen apart are several traits, among them a long finger three, longer than finger 2.

Figure 2. Archaeopteryx bavarica, the Munich specimen, is shown here with elements traced. The hands and feet are reconstructed and a possible clavicle is identified.

Figure 2. Archaeopteryx bavarica, the Munich specimen, is shown here with elements traced. The hands and feet are reconstructed and a possible clavicle is identified. Click to enlarge.

The skull has been disarticulated
but the parts can be put back together. (Fig. 3). If valid, the only large bones I can’t seem to identify are the maxillae. Perhaps they are buried are further scattered beyond the matrix. The premaxillae are broken into several pieces. The dentaries remain connected by anteriorly, taphonomically widened in situ.

Figure 3. The skull of Archaeopteryx bavarica traced and reconstructed.

Figure 3. The skull of Archaeopteryx bavarica traced and reconstructed. The maxilla is missing here.

Here I add
the Munich specimen of Archaeopteryx to the large reptile tree (Fig. 4) and recover it basal to the Scansoropterygidae, the clade of basal birds that shares a long finger 3. Here all of the employed Archaeoptetryx specimens are sisters, yet they nest at the bases of three clades of derived birds. This aspect of their interrelationships has not been explored previously (to my knowledge). Rather only one (or perhaps two when Wellnhoferia was employed) Solnhofen birds have been employed in prior studies.

Figure 4. Here I add the Munich specimen of Archaeopteryx to the large reptile tree and recover it basal to the Scansoropterygidae, the clade of basal birds that shares a long finger 3.

Figure 4. Here I add the Munich specimen of Archaeopteryx to the large reptile tree and recover it basal to the Scansoropterygidae, the clade of basal birds that shares a long finger 3. All of the employed Archaeoptetryx specimens are sisters, yet they nest at the bases of three clades of derived birds. This aspect of their phylogeny has not been explored previously. Rather only one Archaeopteryx has been employed in prior studies.

The nesting of A. bavarica 
at the base of the Scansoriopterygidae provides a fitting finish to this multi-post study, based on a hunch that there was more variety in Solnhofen basal birds than the generic name of Archaeopteryx might suggest. Others have also noticed differences (so no novel hypotheses here) and some have erected new species for referred specimens. Some have not. Others have created new genera. I don’t think anyone has yet employed these six, or any six specimens of Solnhofen birds in a large phylogenetic analysis. This post can be a starting point for for just such an experiment conducted by academics. I am not the person to do it, as so many referees on so many rejected papers have indicated previously. And… I have not seen any of these specimens firsthand. But I have included them in a large gamut phylogenetic analysis (Fig. 4).

Figure 1. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

Figure 5. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

References
Wellnhofer P 1993. Das siebte Exemplar von Archaeopteryx aus den Solnhofener Schichten. Archaeopteryx 11; pp. 1-48,

Berlin Archaeopteryx skull under DGS

The Berlin Archaeopteryx
(MB.Av.101, A. siemensii, Dames 1897) has been traced (Fig. 1) and added to the Large Reptile Tree where it nests basal to the London specimen and the Enantiornithes, close to the base of the rest of all birds. Thus this fossil is a primitive, plesiomorphic specimen. Earlier we looked at other Archaeopteryx specimens here, here and here.

Once again
this unique specimen shows why you should not take and combine elements from several Archaeopteryx specimens to create an ‘ideal’ skull.

Figure 1. The Berlin Archaeopteryx, MB.Av.101, shown here in situ and with DGS tracing and reconstruction. The occiput is segregated to the left as is. Similarly, the palate bones are not reconstructed here. They need more examination to determine their outlines. The cranium was crushed. Perhaps it was not as tall in vivo as it appears here in situ. Let me know if you see any mistakes here or if you have pdfs of pertinent literature.

Figure 1. The Berlin Archaeopteryx, MB.Av.101, shown here in situ and with DGS tracing and reconstruction. The occiput is segregated to the left as is. Similarly, the palate bones are not reconstructed here. They need more examination to determine their outlines. The cranium was crushed. Perhaps it was not as tall in vivo as it appears here in situ. Let me know if you see any mistakes here or if you have pdfs of pertinent literature.

Relatively little
has shifted in this specimen, the classic and complete Archaeopteryx (Fig. 2).

Figure 2. The Berlin specimen of Archaeopteryx (MB.Av.101) with elements traced and the pes reconstructed from visible elements of both feet.

Figure 2. The Berlin specimen of Archaeopteryx (MB.Av.101) with elements traced and the pes reconstructed from visible elements of both feet.

Soft tissue
makes this specimen very exciting. Soft tissue either obscures the clavicle or creates the illusion of a clavicle. The anterior gastralia extend to the coracoids, but, just as in derived birds, a sternum appears to be developing ventral to the anterior gastralia, perhaps unossified at this stage.

Speaking of Archaeopteryx skulls…
I was not aware of the Alsono et al 2004 paper on the extrication and CT scanning of the London specimen skull until this evening. I have made the necessary changes warranted by the additional data (Fig. 3).

Figure 1. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

Figure 5. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

References
Dames W 1897.  Ueber Brustbein, Schulter-und Beckengürtel der Archaeopteryx [About sternum, shoulder and pelvic girdles of Archaeopteryx.].  Sitz.-Ber. Akad. Wiss. Berlin 1897 818-834, 3 figs.

Wellnhoferia (the Solnhofen specimen of Archaeopteryx)

Updated Novermber 6, 2015 with a new reconstruction. M. Mortimer provided a necessary critique (see comments). I rushed this online yesterday without tracing gastralia, I thought the scapulae extended further beneath the skull, I misinterpreted several pectoral elements and the humeri. A second look brought these in closer accord with sister taxa. 

Earlier we looked at three other Archaeopteryx specimens and noted that they nested at the bases of distinct clades, the Enantiornithes and the Euornithes. Here we’ll add the Solnhofen specimen of Archaeopteryx (aka Wellnhoferia, Elzanowski 2001, Fig. 1) and a few other taxa to the large reptile tree (601 taxa) to see where they nest.

Figure 1. Wellnhoferia grandis added to the large reptile tree nests at the base of all extant birds, Euornithes, and their extinct relatives, distinct from three other Archaeopteryx specimens. The skull is poorly preserved but these parts, if valid, are preserved in impressions, No sternum or clavicles have been found. Rather the gastralia extend to the coracoids here.

Figure 1. Wellnhoferia grandis added to the large reptile tree nests at the base of all extant birds, Euornithes, and their extinct relatives, distinct from three other Archaeopteryx specimens. The skull is poorly preserved but these parts, if valid, are preserved in impressions, No sternum or clavicles have been found. Rather the gastralia extend to the coracoids here.

Distinct from the other Archaeopteryx specimens,
Wellnhoferia has a shorter tail, a precursor structure to the very short tails of extant birds. This specimen (BSP 1999) nests at the base of the clade that includes Confuciusornis to extant birds (Fig. 2).

Figure 2. Theropod dinosaur subset of the large reptile tree showing the nesting of four Archaeopteryx specimens at or near the bases of several basal bird clades, including the Enantiornithes, the Scansoriopterygidae and the Euornithes.

Figure 2. Theropod dinosaur subset of the large reptile tree showing the nesting of four Archaeopteryx specimens at or near the bases of several basal bird clades, including the Enantiornithes, the Scansoriopterygidae and the Euornithes.

The Scansoriopterygidae
nesting as basal birds and other notes and issues raised here (Fig. 2) will be considered in later blogs.

Figure 3 Reconstruction of the pes of the Wellnhoferia. A tiny p4.3 is visible. Also see Figure 3a for a closeup. This matches the tiny p4.3 in Confuciusornis.

Figure 3 Reconstruction of the pes of the Wellnhoferia. A tiny p4.3 is visible. Also see Figure 3a for a closeup.

Unfortunately
Elzaznowski 2001 missed one pedal phalanx from his reconstruction (Fig. 3). The DGS method helped to recover it.

Figure 3a. Closeup of pedal 4.3 in Wellnhoferia.

Figure 3a. Closeup of pedal 4.3 in Wellnhoferia. Yes, it’s an odd displacement. The smallest pedal digit 4 in Confuciusornis is also p4.3.

A while back
I wondered if the the several specimens assigned to Archaeopteryx were inappropriately lumped based only on the earlier observation that Solnhofen pterosaurs were likewise inappropriately lumped. This has proven to be true. For all the many genera and species discovered from the Solnhofen lagoons, there is more than one basal bird present. Those who have reconstructed the several specimens have not added them to phylogenetic analyses. Those who do phylogenetic analyses have not added several Archaeopteryx specimen to their studies. This is remedied, to a certain extent, here.

I once thought I could add nothing to basal bird studies
since so many workers have published on them. Once again, I am proven wrong. The differences between the specimens are shown to be phylogenetic, not ontogenetic.

Figure 1. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

Figure 5. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

Over the next few days
I will portray a few of these basal birds, perhaps with some new insight, as I did earlier with Yi qi, the inappropriately identified dragon wing bird.

References
Elzanowski A 2001. A new genus and species for the largest specimen of Archaeopteryx. Acta Palaeontologica Polonica 46(4):519-532.

Archaeopteryx: Eichstaett and Thermopolis Specimens

The following GIF animation
(Fig. 1) includes the plate and counter-plate of the Eichstaett specimen of Archaeopteryx. The counter-plate was flipped and un-distorted in Photoshop to match the plate (slightly different camera angles introduced the original keystoning). Together the elements better present data identified in the specimen, including feathers, a sternum and furcula (fused clavicles).

Figure 1. GIF animation of the Eichstaett specimen of Archaeopteryx. Six  frames reveal the plate, counter plate, skeleton and feathers at 5 second intervals. The two final plates identify,  Click to enlarge.

Figure 1. GIF animation of the Eichstaett specimen of Archaeopteryx. Eight frames reveal the plate, counter plate, skeleton and feathers at 5 second intervals. The two final plates identify,  Click to enlarge.

The furcula
is difficult to see, even when traced (Fig. 2). It is merely an impression on the counter-plate and was likely better preserved on the lost portion of the plate. Likewise the clavicles and scapula are difficult to trace.

Figure 2. Pectoral girdle of the Eichstaett specimen of Archaeopteryx.

Figure 2. Pectoral girdle of the Eichstaett specimen of Archaeopteryx. Six frames change every 5 seconds.

There is a broken forearm on this specimen
and perhaps that led to its demise in life.

For some unknown reason, the skull
of this specimen has been difficult to figure. Paul (2002) showed several variations illustrated by several paleontologists. We looked at those here. All but one of these were illustrated with three fenestrae in the maxillary fossa, as shown here (Fig. 3 from Rauhut 2013). Only Heilmann (1926) illustrated a single antorbital fenestra without a fossa.

  1. aof – antorbital fenestra
  2. mf – maxillary fenestra
  3. pro – premaxillary foramen
Figure 3. Archaeopteryx as reconstructed by Rauhut 2013 with three fenestra within the antorbital fossa area. This interpretation is not supported in figure 4. Figure 3. Archaeopteryx as reconstructed by Rauhut 2013 with three fenestra within the antorbital fossa area. This interpretation is not supported in figure 4.

Figure 3. Archaeopteryx as reconstructed by Rauhut 2013 with three fenestra within the antorbital fossa area. This interpretation agrees with the Thermopolis and London specimens, but not the Eichstaett specimen. This is an example of why one should not attempt composites of distinct specimens.

I agree with Heilmann (with regard to the Eichstaett specimen) 
I identify only palatal elements and the inside of the other side of the skull on that specimen. See if you agree (Fig. 4).

Although the skull appears to have a concave upper jaw matching a convex mandible, this may be a taphonomic aftereffect. There is a crack in the anterior surangular at the point of greatest stress and no sister taxa share this morphology.

Figure 4. The Eichstaett specimen of Archaeopteryx as a GIF animated movie of seven frames, each five seconds in length. Note the lack of an antorbital fossa and those two other fenestra. Instead you see the inside of the lower maxilla and mandible along with palatal elements.

Figure 4. The Eichstaett specimen of Archaeopteryx as a GIF animated movie of seven frames, each five seconds in length. Note the lack of an antorbital fossa and those two other fenestra. Instead you see the inside of the lower maxilla and mandible along with palatal elements. A broken vomer may have created the illusion seen by others. Click to enlarge.

As usual
I have not seen the specimen first hand, but have relied on photographs to make these identifications. I have championed the use of digitized photographs and Photoshop to glean data from flattened fossils. Here is one more example of their usefulness.

Figure 5. GIF animation of the maxilla with fossa and accessory fenestra in the Thermopolis specimen of Archaeopteryx not present in the Eichstaett specimen.

Figure 5. GIF animation of the maxilla with fossa and accessory fenestra in the Thermopolis specimen of Archaeopteryx not present in the Eichstaett specimen.

Indeed the Thermopolis and London specimens
do have the antorbital fossa with accessory fenestra illustrated by Rauhut, Paul and others (Fig. 5), but then the Thermopolis specimen nests basal relative to the other two Archaeopteryx specimens (Fig. 6), sharing several easily overlooked traits with the proximal outgroup taxon, Xiaotingia. to the exclusion of the other two Archaeopteryx.

Figure 3. Subset of the large reptile tree (595 taxa) with the addition of the Thermopolis specimen of Archaeopteryx.

Figure 6. Subset of the large reptile tree (595 taxa) with the addition of the Thermopolis specimen of Archaeopteryx.

Comparing these three Archaeopteryx specimens
shows they are indeed sister taxa, but also distinct sister taxa. The high Bootstrap numbers indicates that several characters are not shared by these three taxa.

Figure 1. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

Figure 7. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

Paleontologists:
Please use individual specimens as taxa whenever possible. Don’t blindly combine specimens until you are sure they are conspecific. By taking the short cut and blending two distinct taxa you throw away any chance of identifying subtle interrelationship changes. And you’re letting amateurs, like me, make discoveries that should be yours to make.

References
Heilmann G 1926. The origin of birds. HFG Witherby, London.
Paul G 2002. Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. Johns Hopkins University Press, Baltimore. 406 pp.
Rauhut OWM 2013. New observations on the skull of Archaeopteryx. Paläontologische Zeitschrift 88(2)211-221.

 

 

 

 

Archaeopteryx: the scattered skull of the London specimen

Updated November 8, 2015 with cranial data from Alonso 2004 that I just became aware of.

Figure 1. Archaeopteryx London specimen skull. The anterior is more clearly presented and has been previously illustrated. Here I colorized matrix discontinuities that could be posterior skull elements. At least they all fit together in a basic Archaeopteryx-type skull that matches other specimens.

Figure 1. GIF animation of the skull of the London specimen of Archaeopteryx. Perhaps other bones are also present. If so I did not identify them. The bones here are clear, less clear and not very clear. Compare these colors to the colors in the reconstruction and you’ll see a close correspondence to the bones of other specimens.

As far as I know,
prior workers did not identify or illustrate the posterior skull bones of the London specimen of Archaeopteryx (Fig. 1, but see below). Bones left only the faintest of impressions (if correct here), but seem to correspond to the same bones of better known specimens (Fig. 4). Higher resolution images should confirm or refute these tracings.

New data (November 8, 2015)
came in the form of Alonso et al. 2004, which extricated and CT scanned the skull of the London Archaeopteryx. The new illustration in figure 2 reflects that data. Apologies that I was not aware of this at the time of this first posting.

Figure 2. A new paper (Alsonso et al. 2004) on the cranium of this specimen has come to my attention. The cranium was buried in the matrix and these new illustrations reflect the more complete data.

Figure 2. A new paper (Alsonso et al. 2004) on the cranium of this specimen has come to my attention. The cranium was buried in the matrix and these new illustrations reflect the more complete data.

Every bone here
appears to fit and not stray too far from morphologies established by better preserved skulls. As noted earlier, the large number of premaxillary teeth in the London specimen, along with other traits, make it distinct from the Eichstaett specimen (Figs. 3, 4).

While we’re on the subject of basal birds,
here are a few to scale (Figs. 3, 4). It is notable that the more primitive ones are the smaller ones in this selection of taxa.

Figure 4. Enanthiornithine birds to scale. Click to enlarge.

Figure 4. Enanthiornithine birds to scale. Click to enlarge. Evidently there are a few other taxa without a sternum in this clade.

Be sure to click on figure 4 to see it at full size.
The stem birds, Xiaotingia and Eosinopteryx form a short-face clade with their own autapomorphies. Rahonavis nests with Velociraptor, not with birds in the large reptile tree.

Figure 4. Archaeopteryx and a few stem birds to scale compared to a chicken (Gallus). Click to enlarge.

Figure 4. Archaeopteryx and a few stem birds to scale compared to a chicken (Gallus). Click to enlarge.

The convergence of Late Jurassic birds and Late Jurassic pterosaurs
Here it is clear that the reduction of the long tail in birds occurred with phylogenetic miniaturization and neotony. Earlier I demonstrated the same tail reduction in four clades of pterosaurs that ultimately developed ‘pterodactyloid’-grade traits. They each had their genesis in tiny pterosaurs experiencing phylogenetic miniaturization and neotony.

The refusal of pterosaur workers
to recognize that embryo and juvenile pterosaurs match their parents, and that tiny Solnhofen pterosaurs are adults the size of living hummingbirds is the reason why their cladograms fail to demonstrate gradual accumulations of traits in derived taxa. Odd that tiny birds get novel generic names, but tiny pterosaurs do not.

It may be
that only tiny birds survived the end of the Jurassic, just like tiny pterosaurs. Later they both developed into larger forms.

Rahonavis
(Forster et al. 1998) survived into the Latest Cretaceous (Maastrichtian). Not sure whether it stayed small or evolved smaller than other velociraptors. At present it nests basal to that clade.

I still think reconstructions bring necessary data to the table. 
Hope you do too.

References
Alonso PD, Milner AC, Ketcham RA Cookson MJ and Rowe TB 2004. The avian nature of the brain and inner ear of Archaeopteryx. Nature 430:666-669.
Forster CA, Scott D, Chiappe LM, Krause DW. 1998. The Theropod Ancestry of Birds: New Evidence from the Late Cretaceous of Madagascar. Science 279 (5358): 1915–1919.

Variation in Archaeopteryx and basal bird radiation

Updated October 30, 2015 with a new GIF animation that reveals the furcula of this specimen on the newly added counter-plate. 

The basal bird
Archaeopteryx lithographica  (Meyer 1861, Late Jurassic, Solnhofen Formation ~150 mya, 30-50 cm in length) is known from 12 skeletal specimens, 11 of which are published. Two of those are shown here (Fig. 1). Bennett (2008) reports, over the years workers have split these specimens into six generic and ten species names, while others have lumped them all into a single species.

Figure 1. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

Figure 1. The six tested Solnhofen birds currently named Archaeopteryx, Jurapteryx and Wellnhoferia.

In typical and traditional bird cladograms
only one Archaeopteryx is ever employed. Perhaps the subtle differences between the Solnhofen specimens are considered inconsequential in phylogenetic analyses that attempt to reveal early bird interrelationships. At least that is the tradition.

In like fashion
Solnhofen pterosaurs are also known from hundreds of specimens, but in typical pterosaur analyses only a single specimen from the most common genera, Rhamphorhynchus, Pterodactylus andScaphognathus are ever employed. At least that is the tradition.

As readers know,
I have added dozens of Solnhofen pterosaur specimens to my analysis and found that:

  1. no two tested taxa were identical (except the juvenile/adult pairing in Rhamphorhynchus)
  2. variations in genera are phylogenetic rather than ontogenetic; and
  3. those variations are the overlooked keys to understanding the interrelationships of pterosaurs in general

For instance,
from those results the widely accepted clade, “Pterodactyloidea,” was found to have not one, but four origins, all developing a complete set (rather than a partial set as in wukongopterids) of pterodactyloid-grade traits all by convergence.

So, with the presence of Galapagos-like variation in Solnhofen pterosaurs…
I wondered if there was Galapagos-like variation in the Archaeopteryx specimens. And if so,  what were those variations? Would they be substantial enough to appear in an analysis not focused on birds, like the large reptile tree? (It now includes 594 taxa.)

A little history on Archaeopteryx lumping and splitting
Houck et al (1990) found evidence in scatter plot analysis of immaturity in the six specimens then known and interpreted the specimens as a growth series of a single species.

Elzanowski (2002) rejected the notion that any of the specimens were immature and so recognized the London, Berlin and Munich specimens as three distinct species and the Solnhofen specimen (BSP 1999) as a new genus, Wellnhoferia grandis.

Senter and Robins (2003) repeated the Houck et al analysis with one added and one excluded specimen agreed with Houck et al. on a single species documenting an ontogenic series.

Mayr et al. (2007) described the Thermopolis specimen and lumped all specimens into two species.

Bennett (2008) likewise used statistical analysis in a study of Alligator to document variation a single species, concluding that “lengths of skeletal elements in a sample of a single species can have high correlation coefficients, and that such high correlation coefficients are not indicative of multi-species samples.”

This is all well and good
but where are the phylogenetic analyses? Bennett (1995) lumped all of his Rhamphorhynchus specimens together using statistics, but missed the speciation recovered in phylogenetic analysis. Even the feet show variation! Perhaps the same is true of Archaeopteryx?

I start with just two Archaeopteryx taxa,
the large London and small Eichstaett specimens (Fig.1). I added both to the large reptile tree and was mildly surprised by the unconventional results. The London specimen nested at the base of the few specimens currently tested in the Enantiornithes clade (Fig. 2). The Eichstaett specimen nested at the base of the few specimens tested in the Euornithes clade.

Figure 4. Here I add the Munich specimen of Archaeopteryx to the large reptile tree and recover it basal to the Scansoropterygidae, the clade of basal birds that shares a long finger 3.

Figure 2. Here I add the Munich specimen of Archaeopteryx to the large reptile tree and recover it basal to the Scansoropterygidae, the clade of basal birds that shares a long finger 3.

These are novel nestings
Typically other specimens nest between Archaeopteryx and Enantiornithes. The classic transitional taxa include  RahonavisXiaotingia and Confuciusornis. In the large reptile Rahonavis nests with Velociraptor, Xiaotingia (together with Eosinopteryx) is the proximal outgroup taxon for Archaeopteryx, and Confuciusornis nests as a basal euornithine,

Remember, this is small list of pertinent taxa
with far fewer pre-birds and birds included than are usually found in bird origin cladograms. Likewise, there are also far fewer theropod and bird specific characters employed here.

The key differences
between this study and prior studies are simply the inclusion of one more Archaeopteryx specimen into the matrix, the use of reconstructions, and a set of 228 generic characters that work for reptiles at large, but are not bird or theropod specific.

London specimen enantiornithine traits from the large reptile tree:

  1. snout constricted in dorsal view
  2. nasal shape parallel in dorsal view
  3. premaxilla ascending process not beyond naris
  4. nasals subequal to frontals
  5. maxilla with antorbital fossa
  6. pineal foramen/cranial fontanelle absent
  7. frontal parietal suture not straight
  8. no temporal ledge
  9. quadrate posterior not concave
  10. squamosal + quadratojugal indented, no contact
  11. jaw joint descends
  12. premaxillary teeth: > 4
  13. retroarticular angle: straight
  14. mandible ventrally: straight then convex

Eichstaett specimen euornithine traits from the large reptile tree:

  1. snout not constructed in dorsal view
  2. nasal shape, premaxilla invasion and separation
  3. premaxilla ascending process beyond naris
  4. nasals shorter than frontals
  5. maxilla without antorbital fossa
  6. pineal foramen/cranial fontanelle present
  7. frontal parietal suture straight and wider than n/f suture
  8. squamosal temporal ledge
  9. quadrate posterior concave
  10. only squamosal indented
  11. jaw joint in line with maxilla
  12. premaxillary teeth: 4 or fewer
  13. retroarticular angle: ascends
  14. mandible ventrally: straight then concave

Plus
There are several other traits that are not universal among derived taxa in both clades. These help to lump and split the derived taxa. Request the .nex file here.

Figure 2. London Archaeopteryx pectoral area with a focus on the scapula, coracoid and clavicles.

Figure 2. GIF animation London Archaeopteryx pectoral area with a focus on the scapula, coracoid and clavicles.

And then
there are several enantiornime-euornithine splitting traits not listed as traits in the large reptile tree.

Enantiornithine traits in the London specimen of Archaeopteryx:

  1. coracoid with convex articulation with scapula
  2. coracoid with convex lateral shape
  3. Y-shaped clavicles
  4. metatarsals fused proximally
Figure 2. Pectoral girdle of the Eichstaett specimen of Archaeopteryx.

Figure 2. Pectoral girdle of the Eichstaett specimen of Archaeopteryx. Two frames, each 5 seconds long.

Euornithine traits in the Eichstaett specimen of Archaeopteryx:

  1. coracoid with concave articulation with scapula
  2. coracoid with straight lateral shape
  3. clavicle not preserved
  4. metatarsals: fusion patterns not clear

As mentioned previously
this addition of one more Archaeopteryx to a phylogenetic analysis will not settle any issues. Paleontology rarely settles any issues. But hopefully others will take the time to trace the bones, create the reconstructions and add several Archaeopteryx specimens to future phylogenetic analyses. As has been demonstrated several times now, statistical analyses of Solnhofen taxa don’t reveal what phylogenetic analyses seem to.

References
Bennett SC 1995. A statistical study of Rhamphorhynchus from the Solnhofen Limestone of Germany: Year-classes of a single large species. Journal of Paleontology 69:569–580.
Bennett SC 2008. Ontogeny and ArchaeopteryxJournal of Vertebrate Paleontology 28 (2): 535-542.
Houck MA, Gauthier JA and Strauss RE 1990. Allometric scaling in the earliest fossil bird, Archaeopteryx lithographica. Science 247: 195–198.