Eosinopteryx – part 3 – to scale

Updated November 5, 2015 with a new interpretation of the pectorals,a new nesting and images of Eosinopteryx and Xiaotingia

Sometimes it just helps
to see taxa to scale with possible sisters (Eosinopteryx in this case, Fig. 1). Smaller than Aurornis, Eosinopteryx also had a shorter snout, shorter torso, shorter tail, more robust clavicle and shorter pubis.

Figure 1. Eosinopteryx and kin, including Xiaotingia, Aurornis and Archaeopteryx (Thermopolis).

Figure 1. Eosinopteryx and kin, including Xiaotingia, Aurornis and Archaeopteryx (Thermopolis).

Godefroit et al. (2013) reported, “The straight and closely aligned ulna-radius of Eosinopteryx also means that pronation/supination of the manus with respect to the upper arm would have been limited; combined with the absence of a bony sternum and weakly developed proximal humerus, these attributes suggest that Eosinopteryx had little or no ability to oscillate the arms to produce a wing beat.”

Funny that they didn’t even mention the short coracoid.
The locked down elongate coracoid is a hallmark of flapping tetrapods (pterosaurs and birds) and an elongate clavicle does the same thing in bats.

The ulna is not bowed
in Aurornis or Eosinopteryx. It is bowed in Xiaotinigia and Archaeopteryx and more greatly bowed in subsequent flapping taxa, including oviraptorids by convergence. The coracoid is strut-like and locked down to the sternum in Xiaotingia and Archaeopteryx, perhaps by convergence because overall Archaeopteryx has proportions more similar to Aurornis.

Figure 2. Xiaotingia is an outgroup taxon to basal birds. The left coracoid is broken and reconstructed here. The coracoid should be as deep as the furcula. The coracoid is longer here than in Eosinopteryx implying a greater ability to flap.

Figure 2. Xiaotingia is an outgroup taxon to basal birds. The left coracoid is broken and reconstructed here. The coracoid should be as deep as the furcula. The coracoid is longer here than in Eosinopteryx implying a greater ability to flap.

The bowed antebrachium
produces a parallelogram in living birds that serves to automatically extend and fold the manus bearing the outer flight feathers with flexion/extension of the elbow. Prior to this, muscle power would have to extend and bend the wrist, independent of the flexion/extension of the elbow.

References
Godefroit P, Demuynck H, Dyke G, Hu D, Escuillié FO and Claeys P. 2013. Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications 4: 1394. doi:10.1038/ncomms2389

wiki/Eosinopteryx

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Eosinopteryx – part 2 – Better Resolution = Better Reconstruction

Updated October 23, 2015 with new skull data.

Yesterday we looked at Eosinopteryx (Godefroit et al. 2013, Middle-Late Jurassic, Tiaojishan Formation) and discussed a possible new nesting site (Fig. 1) based on a lack of included short-coracoid taxa preceding Archaeopteryx to compare it with. By comparison, Cosesaurus has a “flapping”-type coracoid and it has much less wing tissue trailing its front limbs. So the long, locked-down coracoid in bird predecessors was among the last traits to evolve, post-dating the appearance of elongated forelimb feathers.

Supplementary information

Figure 1. Supplementary information from Godefroit et al. (2013) showing their nesting of Eosinopteryx with Anchiornis, but the tree lacks several short-coracoid taxa that might provide more parsimonious nesting sites.

Addendum: The analysis of Godefroit et al. (2013) was based on and provided only a segment of an earlier analysis that DID include these more primitive taxa. Thus my doubt is reduced considerably as all pertinent taxa were included. The skull on DGS

Not sure if a skull reconstruction was provided by Godefroit et al. (2013) or not. (not) I’d still like to see the paper. (I have the paper now. ) Even so, in order to create yesterday’s reconstruction I applied DGS (digital graphic segregation) to the skull (Fig. 2). I don’t know birds as well as dinosaurs and did not attempt a palate reconstruction. If I made any mistakes, please send me an email. (Figure 2 is an update based on higher resolution images of an earlier posted figure.)

Figure 2. The skull of Eosinopteryx in situ (above) and reconstructed using DGS.

Figure 2. The skull of Eosinopteryx in situ (above) and reconstructed using DGS.

Above
The skull of Eosinopteryx traced using Photoshop, a process known as DGS or Digital Graphic Segregation. For followers of this blog, these updated images reflect the importance of high resolution data in using DGS. Much like the Hale telescope, greater resolution enables the identification of finer lines and bones. This demonstrates that its not the mechanics of the technique so much, as the intimate knowledge long months of study provides when employed, and higher resolution really helps. (Higher resolution image did provide improved data.)

The premaxilla includes at least three elongated teeth (here seen from the inside). The saddle-shaped nasal was broken into at least four pieces during crushing. The maxilla is decayed beyond the normal fenestration. Here (Fig. 3) I reconstruct it conventionally. There is no elongated posterior lacrimal process and vestigial anterior process as Godefroit et al. (2013) reported. Rather the lacrimal is similar to that of other theropods. They did not provide a reconstruction. An earlier reconstruction of mine misplaced the quadrate articulation, which is repaired here. It also did not recognize the posterior mandible, which in situ is separated from the articular area. But here (Fig. 3) this has been repaired, thanks to theropod expert, M. Mortimer, for pointing this out. It was also overlooked by Godefroit et al. (2013, Fig. 2).

References
Godefroit P, Demuynck H, Dyke G, Hu D, Escuillié FO and Claeys P. 2013. Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications 4: 1394. doi:10.1038/ncomms2389
Paul GS 2010. The Princeton Field Guide to Dinosaurs. Princeton University Press 320 pp.

wiki/Eosinopteryx

Eosinopteryx – part 1 – Feathers, but no flapping

Updated October 23, 2015 with a new skull.

Eosinopteryx brevipenna (Godefroit et al. 2013, Middle-Late Jurassic, Tiaojishan Formation) is represented by a new complete skeleton. It was a feathered theropod dinosaur about 30 cm long. The forelimb feathers were quite long (Fig. 1), but the tail feathers were not.

Paravian? or Preavian?
We’ve been looking for a feathered theropod without elongated coracoids to precede Archaeopteryx. We also need this taxon to be not pre-oviraptorid or pre-alvarezsaurid. The authors argue, with a very extensive phylogenetic analysis, that this is a troodontid resembling Anchiornis, with less extensive feathers on the hind limbs and tail. Anchiornis greatly resembled Archaeopteryx and is, therefore, closely related. Of that, there is no doubt.

Why There is Doubt
I have not created a competing analysis. Checking out Greg Paul’s figure of Anchiornis (Paul 2010), I note his Anchiornis has the short torso and elongated coracoid also seen in Archaeopteryx, troodontids and deinonychosaurs. On October 23, 2015 I added Eosinopteryx to the large reptile tree where it nests between Aurornis and Archaeopteryx as the last theropod that was not a bird. 

Figure 1. Eosinopteryx reconstructed in lateral view. Soft tissue impressions preserved on the fossil are represented here in gray. Note the small size of the coracoid (yellow) and its curved lower rim, which indicates this specimen was a pre-flapping dinosaur. Pedal digit 2 was not modified as a “killing” claw. Elements figured with DGS.

Figure 1. Eosinopteryx reconstructed in lateral view. Soft tissue impressions preserved on the fossil are represented here in gray. Note the small size of the coracoid (yellow) and its curved lower rim, which indicates this specimen was a pre-flapping dinosaur. Pedal digit 2 was not modified as a “killing” claw. Elements figured with DGS.

What sets Eosinopteryx apart from these?
A short coracoid with a broad curved ventral rim – Therefore Eosinopteryx did not flap and was not descended from flappers. We haven’t seen a terrestrial descendant of Archaeopteryx yet without elongated coracoids. For more on this, compare Huaxiagnathus (with its short coracoid) to Velociraptor, (with its long, tall coracoid). Otherwise these two greatly resemble one another, with the former lacking sternal plates, a retroverted pubis and caudal rods. These traits are also lacking in Eosinopteryx.

A relatively smaller skull – Much smaller than in Anchiornis.

A relatively longer torso – Much longer than in Anchiornis.

A relatively shorter pubis – Much shorter than in Anchiornis.

All these traits are primitive for theropods.

Unfortunately, 
Huaxiagnathus
 was not included in the analysis of Godefroit et al. (2013). Neither were oviraptorids or alvarezsaurids. Eosinopteryx
needs to be compared to these missing basal taxa along with the other taxa they previously tested. Once that’s done, let’s see if the topology of the tree doesn’t shift Eosinopteryx down below (more primitive than) Archaeopteryx. 

Addendum: The analysis of Godefroit et al. (2013) was based on and provided only a segment of an earlier analysis that DID include these more primitive taxa. Thus my doubt is reduced somewhat as all pertinent taxa were included.  Even so, I wonder why these two “sisters” don’t look more alike.

If anyone has details on why Godefroit et al. 2013 said the “bone structure would have limited its ability to flap its wings,” I’d like to see it.

Interesting that this birdy topic just came up a few days ago with Mahakala. Reminds me to be careful what I wish for.

References
Godefroit P, Demuynck H, Dyke G, Hu D, Escuillié FO and Claeys P. 2013. Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications 4: 1394. doi:10.1038/ncomms2389
Paul GS 2010. The Princeton Field Guide to Dinosaurs. Princeton University Press 320 pp.

wiki/Eosinopteryx

Sereno on Stage: Must See YouTube Video

Sorry for the short post today.

Dr. Paul Sereno discusses paleontology and extreme dinosaurs for National Geographic

Dr. Paul Sereno discusses paleontology and extreme dinosaurs for National Geographic. Click to see video.

Dr. Paul Sereno discusses Nigersaurus and other Sahara “Extreme Dinosaurs” in this engrossing, extremely well done 45 minute video. See it here. Great details and he’s a great speaker.

Dr. Sereno discusses paleontology here.

New Early Permian(!) pre-lizard found vulcanized!

This page was again modified May 21, 2015 to reflect an new nesting for TA 1045 as a basal varanid. 

Rößler et al. (2012) just published an account of an Early Permian ecosystem preserved by explosive volcanism. Among the illustrated creatures was a single, reptile (Fig. 1, TA1045) approximately 14 cm snout to vent. Despite its apparent similarity to a varanid, it was not immediately apparent what sort of reptile this was to Rößler et al. TA 1045 was included in the large reptile tree and it indeed nested with basal varanids.

Figure 1. Click to enlarge. The Early Permian reptile (TA1045) preserved in volcanic debris, from Roßler et al. 2012. Yes, those are transverse belly scales beneath the ribs.It looks like the complete rostrum was preserved, right to the edge of the matrix. This image is considered low in resolution. More details can be gleaned with better images.

Figure 1. Click to enlarge. The Early Permian reptile (TA1045) preserved in volcanic debris, from Roßler et al. 2012. Yes, those are transverse belly scales beneath the ribs.It looks like the complete rostrum was preserved, right to the edge of the matrix. This image is considered low in resolution. More details can be gleaned with better images.

Figure 2. the TA!045 Permian varanid. This specimen sets the squamates back to the Early Permian and beyond to the Late Pennsylvanian.

Figure 2. the TA!045 early Permian varanid. This specimen sets the squamates back to the Early Permian and beyond to the Late Pennsylvanian.

Phylogenetic analysis
Using DGS to tease out the details, then adding this taxon to the large reptile tree nests TA1045 as a sister to Estesia, an extinct varanid, and Bahndwivici, a basal varanoid. And that makes it the oldest known ancestor of living lizards.

Soft tissue
Flesh and a complete series of belly scales wider than the ribcage make the vulcanized reptile even more interesting, despite the lack of good preservation of the feet and hands.

Distinct from the skull of BahndwiviciTA1045 had a larger orbit, more laterally oriented. The maxilla has a convex ventral margin. Larger and fewer teeth lined the jaws. The mandible was more gracile. The torso was long and sinuous. Wide ventral scales protected the belly. The scapula was highly fenestrated. The hind limbs were much more robust than the forelimbs.

Chronology – This is Where it Gets REALLY Exciting!!
TA1045 pushes the fossilized origins of the lepidosauriformes way back to the early part of the Early Permian (290 mya), within 10 million years of the Carboniferous (Pennsylvannian). That means more primitive lepidosaurs deep into the Pennsylvannian. There must have been an explosive radiation of new lepidosauromorphs at that time, currently unknown as fossils.

References
Rößler R, Zierold T, Feng F, Kretzschmar R, Merbitz M, Annacker V and Schneider JW 2012. A snapshot of an Early Permian ecosystem preserved by explosive volcanism: new results from the Chemnitz Petrified Forest, Germany.PALAIOS 27(11):814-834. pdf online.

Mahakala – Size Evolution Preceding??? Avian Flight

Today we’ll look at a flightless bird/dromaeosaurid: Mahakala.
While the paper by Turner et al. (2007), “A basal dromaeosaurid and size evolution preceding avian flight” (pdf). was ostensibly about the origin of flight in birds, it actually says nothing about taxa preceding Archaeopteryx and neither does their included cladogram. Mahakala (Fig. 1, the new basal dromaeosaurid, as everyone knows, is Late Cretaceous and demonstrates the reduction of the wings FOLLOWING Archaeopteryx, its Late Jurassic predecessor. Lots of birds reduce the wings when they are no longer necessary for flight. Makhala is only one more. If you want to read more about the taxa preceding Archaeopteryx, look here.

Mahakala dromaeosaurFig. 1. Artist’s reconstruction of Mahakala omnogovae, a two-foot-long dinosaur unearthed in the Gobi Desert. © Frank Ippolito This is a good-looking representation of an incomplete fossil.
Some thoughts from Xu Xing in NatGeo 
Xu said a combination of birds’ ability to fly and to evolve quickly might have helped them survive.

“Birds mature within one year, and that gives them the means to adapt very rapidly to big changes in the environment,” he said.

My research indicates some birds take more than one year to mature (ostrich = 3-4 years, crow=2 years). Others take less. Reporters may have reported what they wanted to, perhaps misquoting Xu.

Some thoughts from Alan Turner in NatGeo|

“Paleontologists have long thought that miniaturization occurred in the earliest birds, which then facilitated the origin of flight,” said Alan Turner, lead author on the study and a graduate student at the American Museum of Natural History and Columbia University in New York. “Now, the evidence shows that this decrease in body size occurred well before the origin of birds and that the dinosaurian ancestors of birds were, in a sense, pre-adapted for flight.” Not so. Where’s the logic here? Large wings in the Jurassic clearly preceded the small wings of Mahakala of the Late Cretaceous. And, at least some of the more birdy taxa that followed Archaeopteryx were much, much smaller, as we looked at here.

Although paleontologists have shown that birds evolved from bipedal carnivorous dinosaurs known as theropods, fossil evidence of miniaturization and other characteristics leading to flight have been sparse. Not really… just not studied much. As in pterosaur precursors, everyone is looking for what they think they should find and ignoring what evidence is already out there.

Now Mahakala is providing the first signs of some of these early evolutionary steps. In particular, while other dinosaurs of the Cretaceous Period were evolving in favor of increased body size, Mahakala represented a progressive step towards miniaturization of body forms that would be necessary for feathered dinosaurs to eventually take flight. Not really. Mahakala is about the same size as Archaeopteryx.

“Flight isn’t an easy thing, because you are, in effect, countering the force of gravity,” said Turner. “Being really small appears to be a necessary first step. Other groups that evolved flight, such as pterosaurs and bats, all evolved from small ancestors.” Really? And those ancestors are…????? (Really, I know pterosaurs and bats evolved from small ancestors, see bats here and pterosaurs here. But those specimens are not acknowledged by traditional paleontologists. So, I’m wondering which taxa Turner was referring to? Or hoping for?)

Traditionally it’s been thought that the earliest birds were the first theropods to become really small. With the discovery of Mahakala we were able to show that this miniaturization occurred much earlier.” Ahem. You mean extended much later to the Late Cretaceous. Who was editing/proofing this copy??

 Mahakala shows that dinosaur size decreased progressively as they evolved toward birds. While this is something that has long been expected, Mahakala provides the first empirical evidence of this phenomenon. Again, the charts included in the article say otherwise, both chronologically and phylogenetically.

But what about….?
Now, I realize the Early Cretaceous tritosaur lizard, Huehuecuetzpalli, chronologically succeeded Triassic fenestrasaurs and pterosaurs. However, phylogenetically a sister of Huehuecuetzpalli preceded Triassic fenestrasaurs and pterosaurs. Makhala does not phylogenetically precede Archaeopteryx, according to the published charts, which show  no pre-Archaeopteryx taxa. That’s just not right when other studies have found a series of taxa with a gradually accumulating list of bird traits.

What we know

The origin of birds cladogram.

Figure 2. Click to enlarge. The origin of birds cladogram. Large clades are colorized. Red arrow points to the place on the chart where we will someday place the closest known ancestors of Archaeopteryx.

At least this cladogram (Fig. 2) shows some Triassic and Jurassic taxa (not that that’s required). In any case, we’re still looking for the precursor to Archaeopteryx that is not a closer precursor to oviraptorids, alvarezsaurids, etc. One of the keys to figuring out flightless or flapless taxa that came before or after is the design of the coracoid, as we looked at earlier with the precursors to pterosaurs that were flapping long before they were flying. With a locked down coracoid flapping can progress. With a sliding coracoid (the plesiomorphic condition), not so much.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Turner AH, Pol D, Clarke, JA, Erickson GM and Norell M 2007. “A basal dromaeosaurid and size evolution preceding avian flight” (pdf). Science 317 (5843): 1378–1381. doi:10.1126/science.1144066PMID 17823350.

Pterodactylus on a branch sculpture

Pterodactylus on a cork branch by David Peters, 2013.

Pterodactylus on a cork branch by David Peters, 2013. Private commission.

On occasion I get private requests for pterosaur illustrations and sculptures. Here’s one, fresh in 2013, of Pterodactylus, to scale, on a cork branch. It portrays the wing membranes as they are preserved in the Vienna specimen and others, shallow at the elbow, readily stowed when the wings are folded and ready to deploy in a sailplane or nighthawk configuration when ready to take-off. It also echoes, with appropriate updates, an early Burian painting.

Note the long forelimbs give clearance for the long rostrum when on branches like this.