Procolophonids and look-alikes, like Sauropareion

A recent endaaper
by MacDougall et al. (2013) reported on the post-crania of the Early Triassic reptile, Sauropareion (Fig. 1). The description was excellent.

Unfortunately
they labeled it a procolophonid and a parareptile. That was by tradition, for the most part.

Figure 1. Sauropareion in situ from MacDougall et al 2013.

A phylogenetic analysis was performed by them (Fig. 2) to nest Sauropareion. While their test included several taxa I have not tested (everyone needs a new project for the new year), the large reptile tree found a much different nesting (color notes in Fig 2), at the base of the owenettids, and, by extension, at the base of the Lepidosauriformes, close to Paliguana.

Figure 2. Nesting Sauropareion. Here it nests correctly with owenettids, but the inclusion of pareiasaurids like Sclerosaurus, and diadectids, like Procolophon, is unwarranted, according to the results of the large reptile tree. Also, several taxa that should have been included were not, given the gamut of the inclusion set. Several basal lepidosauriformes should also have been included given their proximity in the large reptile tree. The lack of resolution may be due to the inclusion of unrelated taxa or the incompleteness of the included taxa.

We need to take a large look at procolphonids
Unfortunately Procolophonidae has become a wastebasket taxon for any small reptile with short toes and a large orbit. A large gamut phylogenetic analysis is needed to correctly nest the many taxa that have been attributed to it — and to correctly nest the Procolophonidae itself.

The large reptile tree nests Procolophon, Hypsognathus and Pentaedrusaurus with Diadectes, a taxon typically excluded in prior analyses.

MacDougall et al. include Sclerosaurus, but that taxon nests with pareiasaurs in the large reptile tree.

Phonodus nests with bolosaurs in the large reptile tree, not far from procolophonids and diadectids.

Assumptions and traditions
need to be tested in a larger gamut analysis. If I have any influence over the study of paleontology, this is what I want, a large gamut analysis by someone else to test the large reptile tree.

References
MacDougall MJ, Modesto SP and Botha-Brink J 2013. The postcranial skeleton of the Early Triassic parareptile Sauropareion anoplus, with a discussion of possible life history. Acta Palaentologica Polonica 58(4):737-749.

A funny looking pterosaur toe bone…

Sometimes odd things pop out of fossils.
Here (Fig. 1) is a pterosaur foot (Rhamphorhynchus muensteri,  JME-SOS 4009, no. 62 in the Wellnhofer 1975 catalog). Phalanx p4.1 is greatly expanded, yet no longer than it’s counterpart on the other foot.

Figure 1. Right pes of n62, Rhamphorhynchus muensteri. Note p4.1 is greatly expanded, like a balloon. The left foot is not so afflicted. There is still a claw on digit 4, off the edge of the photo. See if you can see a faint, very faint impression of a web. If you do, then look off to the right and you’ll see that geographical feature continuing beyond the bones. 

Maybe you know what this is…
I don’t know what makes toe phalanges expand like this. It is no longer than the slender phalanx on the left pes, but it is greatly expanded, like a balloon. Is it due to disease or injury?

BTW
Very few Rhamphorhynchus have such a long pedal digit 4. I have only found one other specimen from about 20 or so that I have examined.

I thought you might find it as interesting as I did. 

 

 

 

The Clavicle and Interclavicle of Odontochelys – a proto-turtle

Today, a little snippet about the turtle shell and its origins.

The turtle plastron
(= lower shell) has its origins in the dermal bones of related reptiles. The interclavicle, renamed entoplastron (= gular) in turtles, is incorporated (Fig. 1) in Odontochelys (Li et al. 2008). The clavicles, renamed the epiplastra in turtles, are also incorporated. More can be learned with Proganochelys, a basal turtle, likewise from the Late Triassic.

Modern turtles
modify these patterns somewhat. Pleurodire turtles add an extra scute, the intergular).

Figure 1. Odontochelys in situ exposed ventrally. The interclavicle (renamed entoplastron, in red) and clavicles (renamed epiplastra, in blue) are located here. Here the right clavicle is shown at full length, crushed into the transverse plane. The left clavicle may be likewise crushed into the transverse plane, but it is largely hidden beneath the plastron here. Both extended vertically in vivo.

Earlier we looked at the origin of turtles in Stephanospondylus, an early splinter from the pareiasaur lineage derived from millerettids. Turtle relationships, and many others, are clarified in the large reptile tree.

References
Li C, Wu X-C, Rieppel O, Wang L-T and Zhao L-J 2008. An ancestral turtle from the Late Triassic of southwestern China. Nature 456: 497-501.

wiki/Odontochelys

Tribelesodon/Tanystropheus: rough draft

Before the fossil named “Tribelesodon” (Fig. 1) was identified as a small Tanystropheus with three-cusped teeth (Peyer 1931) it was considered a type of pterosaur with three-cusped teeth (Bassani 1886, Arthaber 1921, Von Nopcsa 1923). So it’s famous.

Figure 1. Tanystropheus (Tribelesodon specimen) from Wellnhofer 1991, part, counterpart and very rough tracing.

The part and counterpart fossil (Fig. 1) of Tribelesodon was housed in Italy’s Museo di Storia Naturale di Milano before it was destroyed by Allied bombs during World War II. Thankfully, Wellnhofer (1991) provided small images of the fossil.

Figure 2. Rough comparisons of the Tribelesodon specimen assigned to Tanystropheus (Peyer 1931) compared to more complete specimens from Europe (MSNM BES SC 1018) and China (IVPP V 14472). The Tribelesodon specimen appears to have had a larger skull and more gracile postcrania, but otherwise closely comparable in size to the IVPP specimen.

Here, very roughly, I trace (Fig. 1) and uncoil the neck (Fig. 2) using DGS and compare it to more complete specimens from Europe and China. The Tribelesodon specimen appears to have had a larger skull and more gracile postcrania, but otherwise closely compares in size to the IVPP specimen. I’ll readily admit some bones may be misidentified and vaguely indicated, especially around the pelvis. The details, in this case, are not that important. Overall, it’s pretty obvious what we have here.

Earlier we looked at several of the largest specimens of Tanystropheus, the evolution of Tanystropheus and other topics related to this genus.

Thanks to Tracy Ford for providing me a scale bar on this specimen.

References
Bassani F 1886. Sui Fossili e sull’ età degli schisti bituminosi triasici di Besano in Lombardia. Atti della Società Italiana di Scienze Naturali 19:15–72.
Li C 2007. A juvenile Tanystropheus sp.(Protoro sauria: Tanystropheidae) from the Middle Triassic of Guizhou, China. Vertebrata PalAsiatica 45(1): 37-42.
Meyer H von 1847–55. Die saurier des Muschelkalkes mit rücksicht auf die saurier aus Buntem Sanstein und Keuper; pp. 1-167 in Zur fauna der Vorwelt, zweite Abteilung. Frankfurt.
Nosotti S 2007. Tanystropheus longobardicus (Reptilia, Protorosauria: Reinterpretations of the anatomy based on new specimens from the Middle Triassic of Besano (Lombardy, Northern Italy). Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano, Vol. XXXV – Fascicolo III, pp. 1-88
Peyer B 1931. Tanystropheus longobardicus Bass sp. Die Triasfauna der Tessiner Kalkalpen. Abhandlungen Schweizerische Paläontologie Gesellschaft 50:5-110.
Renesto, S. 2005. A new specimen of Tanystropheus (Reptilia Protorosauria) from the Middle Triassic of Switzerland and the ecology of the genus. Rivista Italiana di Paleontologia e Stratigrafia, 111(3): 377–394.
Wellnhofer P 1991. The Illustrated Encyclopedia of Pterosaurs. Salamander Books Ltd., London. 192 pp.
Wild R 1973. Die Triasfauna der Tessiner Kalkalpen XXIII. Tanystropheus longobardicus(Bassani) (Neue Ergebnisse). – Schweizerische Paläontologische Abhandlungen 95: 1-16.

wiki/Tanystropheus

Giant Tanystropheus to scale, and a tribute to Rupert Wild

Figure 1. Click to enlarge. Four large Tanystropheus specimens in situ and roughly reconstructed. The human silhouette is 6 feet (1.8m) tall. In situ images from Wild 1974. Note the presence and absence of epipubic bones along with the variation in skull size.

Tanystropheus (Fig. 1, Middle Triassic, Europe, von Meyer 1852) was discovered in the 19th century, but not fully realized for what it was until Peyer 1931. One early specimen, named Tribelesodon, was mistaken for a pterosaur (Basani 1886, Arthaber 1921, Von Nopcsa 1923). The long neck bones were mistakenly compared to wing bones. The foot, with its long p5.1 digit, were indeed very pterosaurian in general morphology. So the taxonomic mistake had some basis.

Lesson learned here:
respected scientists can make mistakes. And these mistakes can become traditions until falsified. A reconstruction might have helped.

Peyer’s contribution
New complete skeletons of Tanystropheus described by Peyer (1931) solved the basic problem by showing the hyper-elongate bones actually belonged between the skull and torso.

Wild’s contribution
In 1974 Rupert Wild reviewed all the available material (27 specimens) of T. langobardicus. A few are pictured above (Fig. 1). Before the advent of phylogenetic analysis, Wild had the insight to label them Reptilia > Lepidosauria > Squamata > Lacertilia > Tanysitrachelida > Tanystropheidae. This is largely confirmed by the present large reptile tree. (The term “Lacertilia” includes all lizards, but not snakes, so it is a paraphyletic taxon in the large reptile tree. The term “Tanysitrachelida” (Peyer 1931) is no longer in use. Tanystropheidae includes other long-necked reptiles, such as  Langobardisaurus, Pteromimus, Tanytrachelos and Amotosaurus, all very much smaller taxa.)

To his credit,
Wild (1978) also was among the first to promote the idea that pterosaurs were not archosaurs, but something else along the lines of an eosuchian, a term little used today. Back then an Eosuchian was commonly considered a basal diapsid, like Youngina, a genus then considered close to the ancestry of both lepidosaurs and archosaurs. Now, thanks to the large reptile tree, we know that lepidosaurs and archosaurs are not related, except at a very basal reptile level. We also know that diapsids are diphyletic, having two origins. Wild’s heretical break with tradition is to be applauded. At the time closer relatives to pterosaurs, like Langobardisaurus, Cosesaurus, Sharovipteryx and Longisquama were either unknown or just becoming known.

Others
(Carroll 1989, etc.) placed Tanystropheus outside the Archosauriformes along with rhynchosaurs, which makes absolutely no sense. Still others (Renesto 2005 following tradition) placed Tanystropheus within the Protorosauria, which makes more sense, but, unfortunately, this is by untested tradition only.

Phylogenetic testing using more taxa in the large reptile tree clarifies relationships. Tanystropheidae nest between Huehuecuetzpalli + Macrocnemus and Cosesaurus within the Tritosauria, outside of the Squamata.

Despite what Wikipedia tells you, phylogenetic analysis recovers Dinocephalosaurus as a convergent form derived from Macrocnemus, not directly related to Tanystropheus despite   the roughly similar appearance and size.

Earlier we looked at several solutions to the niche and posture of Tanystropheus. Here you can see the ancestry and sisters of Tanystropheus.

Here (fig. 1) we can see that some large Tanystropheus specimens had a larger skull. Others had a smaller skull. Some had epipubic bones. Others did not. More precision in creating the reconstructions might someday reveal other differences not readily visible in these roadkill fossils.

References
Bassani F 1886. Sui Fossili e sull’ età degli schisti bituminosi triasici di Besano in Lombardia. Atti della Società Italiana di Scienze Naturali 19:15–72.
Li C 2007. A juvenile Tanystropheus sp.(Protoro sauria: Tanystropheidae) from the Middle Triassic of Guizhou, China. Vertebrata PalAsiatica 45(1): 37-42.
Meyer H von 1847–55. Die saurier des Muschelkalkes mit rücksicht auf die saurier aus Buntem Sanstein und Keuper; pp. 1-167 in Zur fauna der Vorwelt, zweite Abteilung. Frankfurt.
Nosotti S 2007. Tanystropheus longobardicus (Reptilia, Protorosauria: Reinterpretations of the anatomy based on new specimens from the Middle Triassic of Besano (Lombardy, Northern Italy). Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano, Vol. XXXV – Fascicolo III, pp. 1-88
Peyer B 1931. Tanystropheus longobardicus Bass sp. Die Triasfauna der Tessiner Kalkalpen. Abhandlungen Schweizerische Paläontologie Gesellschaft 50:5-110.
Renesto, S. 2005. A new specimen of Tanystropheus (Reptilia Protorosauria) from the Middle Triassic of Switzerland and the ecology of the genus. Rivista Italiana di Paleontologia e Stratigrafia, 111(3): 377–394.
Wild R 1973. Die Triasfauna der Tessiner Kalkalpen XXIII. Tanystropheus longobardicus(Bassani) (Neue Ergebnisse). – Schweizerische Paläontologische Abhandlungen 95: 1-16.
Wild R 1978. Die Flugsaurier (Reptilia, Pterosauria) aus der Oberen Trias von Cene bei Bergamo, Italien. Bolletino della Societa Paleontologica Italiana 17(2): 176–256.

wiki/Tanystropheus

Where is the pectoral girdle on this pterosaur?

This is a game
to see how sharp-eyed you are. Below is Rhamphorhynchus intermedius in situ, virtually completely articulated. Even so, you might have difficulty finding the elements of the pectoral girdle here (Fig. 1).

Figure 1. Rhamphorhynchus intermedius. Where are the pectoral girdle elements. Scroll down for one interpretation.

Scroll down to see one interpretation.

Down.

Down.

Down.

Down.

Down.

Down.

Down.

Here is one solution (Fig. 2):

Figure 2. Rhamphorhynchus intermedius with pectoral elements colorized. See how much easier it is when the bones have color added? How well did your interpretation match? Scapula in red. Coracoids in green. Sternal complex in yellow. Humerus in blue.

Let DGS (Digital Graphic Segregation) work for you.
During crushing the coracoids criss-crossed. The posterior gastralia shifted forwards and overlying matrix slightly obscures the rostral profile. Otherwise, it’s all there, including a meal at the rear of its gut.

References
Koh TP 1937. Unterscuchungen über die Gattung Ramphorhynchus. – Neues Jahrbuch Mineralogie, Geologie und Palaeontologie, Beilage-Band 77: 455-506.
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33.Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.

wiki/Rhamphorhynchus

The Amphibian within an Amphibian

Everyone has heard of the famous, “Fish within a Fish.” Here (Fig. 1), not quite within, perhaps, but apparently choking on its prey is an amphibian, Sclerocephalus, within (at least partially) another, larger amphibian. News for this fossil up for auction was posted in late September. More here.

Figure 1. I know, it’s not exactly under our charter, but here one amphibian is choking on another smaller one. Sclerocephalus is the genus.

It’s a dog-eat-dog world out there. 
The fossil dates to the Permian period, around 259m-251m years ago. The predator has been identified as a juvenile Sclerocephalus haeuseri – a carnivorous amphibian approximately 28 inches in length. The smaller fossilized amphibian is tentatively identified as another species, Cherlyderpeton latirostris, but it may be a younger version of the animal that ate it.

More here. News as late as November did not indicate the date of the auction or highest bid of the fossil.

 

Viviparity in lizards

A new paper by Pyron and Burbrink (2013) combines lizard viviparity and lizard phylogeny and finds multiple origins for viviparity…and, multiple reversals to oviparity. The paper also suggests that the basal condition in lizards was oviparity. Only living taxa were tested.

Figure 1. From Wang and Evans 2011, a gravid Cretaceous lizard with 2 embryos. Odd that they are located as high as the forelimb, but when you have 15, allowances have to be made.

Earlier, Wang and Evans (2011) produced fossils of a Cretaceous lizard and her embryos (Fig. 1), all 15 of them!

From the Wang and Evans abstract:
“Although viviparity is most often associated with mammals, roughly one fifth of extant squamate reptiles give birth to live young. Phylogenetic analyses indicate that the trait evolved more than 100 times within Squamata, a frequency greater than that of all other vertebrate clades combined. However, there is debate as to the antiquity of the trait and, until now, the only direct fossil evidence of squamate viviparity was in Late Cretaceous mosasauroids, specialised marine lizards without modern equivalents. Here, we document viviparity in a specimen of a more generalised lizard, Yabeinosaurus, from the Early Cretaceous of China. The gravid female contains more than 15 young at a level of skeletal development corresponding to that of late embryos of living viviparous lizards. This specimen documents the first occurrence of viviparity in a fossil reptile that was largely terrestrial in life, and extends the temporal distribution of the trait in squamates by at least 30 Ma. As Yabeinosaurus occupies a relatively basal position within crown-group squamates, it suggests that the anatomical and physiological preconditions for viviparity arose early within Squamata.”

I would hasten add: perhaps not early in pylogeny, but often. Note these yabeinosaurs (Fig. 1) are beneath the rib cage close to the humerus. Moreover, the orientation is not head first toward the cloaca. Evidently it all works out.

We’ve seen fossils of reptiles huddling together in Decuriasuchus, Heleosaurus and others.

We’ve also looked a possible viviparity in mesosaurs. Ichthyosaurs and plesiosaurs are also notable live-bearers. Pterosaurs maintained embryos within the mother until shortly before hatching took place, based on the extreme thinness of the leathery eggshells and the degree of development of known embryos.

References
Pyron RA and Burbrink FT 2013. Early origin of viviparity and multiple reversions to oviparity in squamate reptiles. Ecology letters. doi: 10.1111/ele.12168.
Wang Y and Evans SE 2011. A gravid lizard from the Cretaceous of China and the early history of squamate viviparity. Naturwissenschaften Sept 98(9):739-43.

Walking with Dinosaurs – The Movie

Well, it’s getting bad reviews, mostly and only for the sound track. Otherwise it looks spectacular, except for the disfigured pterosaurs. Here’s the poster with editorial comments added, followed by a selection of reviewer comments from rottentomatoes.com

Figure 1. Walking with Dinosaurs poster. Again, disfigured pterosaurs.

RottenTomatoes.com Reviews:
“The photo-realistic look is striking, but the dialogue is occasionally wince-inducing. Think a sub-par Flintstones episode.”

“The beauty and majesty of the great creatures is marred a bit by too much focus on poop and barf jokes, silly winks at the audience,” and distracting anthropomorphism.”

“If you’re a fan of the 1999 BBC documentary series Walking with Dinosaurs and are hoping for more of the same, get ready for an Apatosaurus-sized level of disappointment from Walking with Dinosaurs 3D.”

“Features animation stunning and accurate enough to make up for its simple story and unnecessary voice-over dialogue.”

“Walking With Dinosaurs: The Movie boasts some impressive special effects but is ultimately let down by a terrible script, a dull story and a poorly conceived American voice dub that is extremely grating.”

YouTube previews London Gala Screening here and here.

Standard trailer here.

Stalking vs. Wading: Azhdarchids Round 2

Tetrapod Zoology by Darren Naish is defending stalking vs. wading azhdarchids here. In a reply to their PlosOne paper here, I brought up some issues regarding modern analogs, recounted here.

The issue today is Naish’s inappropriate use of disrespectful adjectives, even in his own blog. I’m not annoyed by such adjectives. But I am concerned for Naish’s reputation and respect, which can take a turn for the worse on his own accord if current patterns persist. It’s always better to take the high road, Darren.

Footnotes follow yellow numbers below.

Quoting Darren Naish:
“The terrestrial stalking model: challenged!
However,[1] if there’s one thing I’ve learnt about human nature, it’s that people will refuse to give up on poorly supported and even nonsense ideas, even when there’s strong or overwhelming evidence to the contrary. So there are still people supporting the idea of water-trawling azhdarchids and wading azhdarchids and so on. In recent months, two challenges to the terrestrial stalking hypothesis have appeared.

The first (I want to spend as little time as possible on this one) comes from the [2] indefatigable David Peters. Peters challenged our hypothesis by posting a comment at PLoS (that’s right, a 2013 comment on an article published in 2008. [3] Weird): he pointed to his own [4] highly suspect phylogenetic results to support the idea that azhdarchids descended from “petite” “micro-azhdarchids” that, [5] in his view, were most likely waders, and he also challenged the idea that azhdarchids look at all like ground hornbills. Mark and I responded (and then responded again, when he responded to our response): you can read the entire chain of correspondence here.”

[1] First Naish bathes what follows with this degrading preamble.

[2] “indefatigable,” as if this pest just won’t go away.

[3] Why paint this as “weird”?

[4] “Highly suspect” is one way of pointing the finger when you have no evidence to the contrary.

[5] Naish’s attempt at isolation makes it seem that I am an outlier, yet the innumerable Crayssac ptero beach wading walking (what’s the difference when there is surf?) tracks were made by similar size and type pterosaurs.

I encourage you to read Naish’s comments and rejoinders with an eye toward his tone of disrespect and ridicule. If we’re just talking about facts and hypotheses, then there is no need to cast the other author in such a light. If a tenured professor had offered the same comments, I can’t see how Naish would adopt the same tone.

Let’s just get down to the animal and its behavior with due respect. After all, we’re talking about a pterosaur behavior that could go either way, or both! whether ankle deep in water or mud or on dust and vegetation.

Even so, it’s still important to bring up salient points when dealing with Science. That’s how we progress.

By trying to make the other person look bad, popular opinion can sometimes swing the other way. And Darren is too valuable a scientist to let that happen.