The real Proterochampsa

Drawings are great.
Reig (1959) gave us a drawing of Proterochampsa (Fig. 1), and it was good enough to nest it correctly. This is the best we’ve had for decades.

Figure 1. Proterochampsa as drawn by Reig 1959..

Photographs are better. 
Trotteyn (2011) was kind enough to include a photograph or three of the actual specimen (Fig. 2) in her PhD dissertation. It’s a little different, and provides great data.

Figure 2. The skull of Proterochampsa (PVSJ 77) colorized here for bone identification. The mandible was rotated during crushing. Tip of the mandible is oddly shaped, perhaps due to breakage. Not sure. Most of the teeth are broken at the root line. DGS provides a little more detail on a difficult skull. 

DGS provides a little more detail here. And we can trust the photo a little more than the drawing. It’s a shame they didn’t provide a photo decades ago.

The holotype (PVSJ 77) is only known from a skull. Earlier we looked at a much larger Proterochampsa (PVSJ 606) known from more complete material.

References
Reig OA 1959 Primeros datos descriptivos sobre nuevos Reptiles Arcosaurios del Triasico de Ischigualsto (San Juan, Argentina): Revista de la Asociacion Geologica Argentina, tomo 13, n. 4, p. 257-270.
Trotteyn MJ and Haro JA. In Press. The braincase of a specimen of Proterochampsa Reig (Archosauriformes: Proterochampsidae) from the Late Triassic of Argentina. Paläontologische Zeitschrift. Published on-line May 11 2010. DOI 10.1007/s12542-010-0068-7
Trotteyn MJ 2011. Material postcraneano de Proterochampsa barrionuevoi Reig, 1959 (Diapsida: Archosauriformes) del Triásico Superior del centro-oeste de Argentina. Ameghiniana 48:424-446.
Trotteyn MJ 2011. Revisión osteologica, análisis filogenético y paleoecología de proterochampsidae (Reptilia – Archosauriformes). Tesis Doctoral. Instituto y Museo de Cienciea Naturales Universidad Nacional de San Juan. CONICET.

wiki/Proterochampsa

 

The vampire pterosaur has a new sister: Daohugoupterus

Cheng et al. (2014)
present a new small, late Jurassic pterosaur, Daohugoupterus. They were not quite sure what it was, assigning it to Pterosauria incerta sedis. The specimen is represented by an articulated skeleton lacking hind limbs, the anterior skull and two proximal wing phalanges (Fig. 1). Wing tip soft tissue was preserved. I believe the ulna and radius are just beneath the surface based on the positions of the humerus and carpus/metacarpus. The rest of the wing is likely twisted beneath these elements as the distal two wing phalanges frame the soft tissue.

Figure 1. Click to enlarge. Daohugoupterus in situ, colorized (left) and as originally traced (right). You’ll note that DGS pulled out more details than firsthand tracing.

From their abstract:
“Daohugou is an important locality of the Jurassic Yanliao Biota, where
only two pterosaurs have been described so far (Jeholopterus and
Pterorhynchus). Here we report a new genus and species, Daohugoupterus
delicatus gen. et sp. nov. (IVPP V12537), from this region, consisting
of a partial skeleton with soft tissue. The skull is laterally
compressed, differing from Jeholopterus. The antorbital fenestra is
larger than in Pterorhynchus. The upper temporal fenestra is unusually
small. The short cervical vertebrae bearing cervical ribs indicate
that it is a non-pterodactyloid flying reptile. The sternal plate is
triangular, being much wider than long. The deltopectoral crest of
humerus is positioned proximally and does not extend further down the
shaft, a typical feature of basal pterosaurs. Daohugoupterus also
differs from the wukongopterids and scaphognathids from the Tiaojishan
Formation at Linglongta, regarded to be about the same age as the
Daohugou Bed. The new specimen increases the Jurassic
non-pterodactyloid pterosaur diversity of the Yanliao Biota and is the
smallest pterosaur from Daohugou area so far.”

DGS
Digital Graphic Segregation was used to pull details out of the skeleton. While the original paper described small upper temporal fenestra (that are indeed there) the figure did not show this detail. No skull bones were identified. The vertebrae were outlined without details. Color tracing and reconstruction (fig. 2) help bring this specimen ‘back to life.’ The length of the rostrum is unknown, but after phylogenetic analysis nesting with Jeholopterus, the rostrum was reconstructed like it’s sister taxon.

Reconstruction
A reconstruction of all available elements resulted in a sister to Jeholopterus, sharing many traits including the strong reduction of anterior cervical vertebrae, robust cervical vertebrae posteriorly, wide ribs creating a pancake-like torso, and a fragile skull with very large orbit (Fig. 2). Notably, Jeholopterus was a contemporary from the same Late Jurassic formation.

Figure 2. Click to enlarge. Daohugoupterus reconstructed.

If you take a bone-by-bone survey
of the the DGS tracing vs. the original tracing (Fig. 1), you’ll find many differences. This is a difficult fossil and the accuracy of my tracings depending to a large part on testing each part within an evolving reconstruction (Fig. 3). Attempting reconstructions of roadkill pterosaurs is something conventional paleontologists are loathe to do, and they never ask me to help. Hence this blog.

Figure 3. Jeholopterus in lateral view. Note the wide ribs.

In a side-by-side comparison (Fig. 4)
Jeholopterus and Daohugoupterus do share many traits and are roughly the same size. Daohugoupterus does not have the robust limbs and surgically curved claws that Jeholopterus has, but Daohugoupterus does have enormous eyes, probably for night vison. They share a wider than deep torso which enables them to cram their bellies, but still keep an aerodynamic disc-like shape (also see Sharovipteryx for something similar). They also share a very robust neck that gets very gracile close to the skull. I presume this gives both pterosaurs a wider range of motion at the skull/neck juncture. But why does most of the neck have to be stronger than the dorsal vertebrae?

Figure 3. Jeholopterus and Daohugoupterus in side-by-side comparison to scale. The wings were relatively short in Daohugoupterus and the pelvis was small. The skull was relatively narrower, but the torso was just as broad.

On a side note
Experiment.com has accepted by submission and my first crowd-source funding project has started today. See details at:
https://experiment.com/projects/the-reptile-evolution-project

References
Cheng X, Wang X, Jiang S and Kellner AWA 2014. Short note on a non-pterodactyloid pterosaur from Upper Jurassic deposits of Inner Mongolia, China. Historical Biology (advance online publication) DOI:10.1080/08912963.2014.974038

 

Another odd rhynchocephalian: Ankylosphenodon

You don’t find very much
about Ankylosphenodon pachyostosus (Reynoso 2000) online, even though it is odd and known by a complete skeleton. It’s a basal rhynchocephalian, nesting between Gephyrosaurus and Marmoretta in the large reptile tree. The long torso and tail, along with those small limbs gives credence to the possibility that Marmoretta and Megachirella were similarly equipped (they are known from a skull and anterior torso only) at the base of the Pleurosauridae, which we looked at earlier here.

Figure 1. Ankylosphenodon pachyostosus. Click to enlarge. This long-bodied taxon nests at the base of the pleurosaurs, Marmoretta and Megachirella.

Middle Cretaceous, Mexico, considered an herbivore. Martinez et al. 2013) nested Ankylosphenodon between Sphenodon and Clevosaurus and Sphenotitan, but Marmoretta, Megachirella, and Gephyrosaurus were not included in their taxon list and neither were a host of derived rhynchocephalians. `

From Wikipedia (translated from Italian, I think).
“This animal had a body rather robust, with short legs positioned at the sides of the body and a skull from the remarkable features. These included a set of teeth unusual: there were, in fact, long teeth roots open, deeply “embedded” in the jaw and placed in the vicinity of the channel Meckel . Another feature dell’anchilosfenodonte was given by significant thickening of the ribs and vertebrae ( pachiostosi ), a feature that normally is found in aquatic vertebrates.”

References
Reynoso VH 1996. Early Cretaceous Lepidosaurs (Reptilia: Diapsid) from Central Mexico and the Phylogeny of Lepidosauromorphs. 369 pp. Unpublished PhD Thesis, McGill University, Montreal, Canada.
Reynoso VH 2000. An unusual aquatic sphenodontian (Reptilia: Diapsida) from the Tlayua Formation (Albian), central Mexico. Journal of Paleontology 74:133-148.

Kallimodon(?) reconstructed

Figure 1. Kallimodon from WikiCommons.

I found this purported Kallimodon specimen on WikiCommons and traced it out. The museum number is not available. If anyone knows it, please let me know. I can’t say if it is Kallimodon or not. I don’t have access to images of the holotype (1887-VI-I), or if I do (there are several specimens on Google), not one is identified as the holotype.

Figure 2. Kallimodon? in situ after adjusting levels and a tracing. Possible eggs are in light blue on the in situ specimen. This specimen is small, only about 20 percent larger than pictured here.

Whatever the provence of this specimen, DGS enables details to be brought out, despite or because of crushing. There is a palate labeled Kallimodon, but it obvious comes from another specimen. And I can’t be sure it is the holotype without seeing the label.

Figure 3. Kallimodon? reconstructed. This taxon, whether it is Kallimodon or not, nests with Sphenodon, but has distinct proportions, with a small skull, long torso and long legs.

Though distinct from all other rhynchocephalians, this specimen nests with Sphenodon, the living rhynchocephalian. There is also some confusion regarding the naming and numbering of this taxon:

Etymology
Homoesaurus pulchellus Zittell, 1887
Kallimodon pulchellus (Zittell, 1887) Frickhinger 1994
Locality: Kelheim, Bayern (Bavaria) State, Germany.
Horizon: Solnhofen.
Age: Tithonian Stage, Upper Malm Epoch, Late Jurassic.

References
Cocude-Michel, M 1963.  Les rhynchocéphales et les sauriens des calcaires lithographiques (Jurassique supérieur) d’Europe occidentale.  Nouv. Arch. Mus. Hist. Nat. Lyon 7 187 pp.
Frickhinger, K A 1994. Die Fossilien von . The Fossils of Solnhofen: Goldschneck-Verlag, 336pp.
Zittell KA 1887. Rhynchocephalia – Handbuch der Palaeontologie 3:583-800. München and Leipzig.

Paleofile

 

Leptosaurus: another transitional taxon between Rhynchocephalia and Rhynchosauria

Leptosaurus, a very small rhynchoceplian basal to Sapheosaurus and Noteosuchus on one branch, Trilophosaurus, Mesosuchus and rhynchosaurs on the other. Teeth are not fused to the jaws. Astragalus not fused to the calcaneum. Note the very tiny pectoral girdle. Preserved in ventrolateral view, the nares are not visible, so perhaps they were dorsal as in rhynchosaurs.

Leptosaurus pulchellus (Fitzinger 1837, Zittel 1887, Renesto and Viohl 1997; aka: Kallimodon Cocude & Michel, 1963) SCHA 40 Late Jurassic, Tithonian Stage, Germany,
155.7 to 150.8 Ma.

Holotype: Leptosaurus neptunicus Fitzinger 1837.

Rhynchocephalians are generally not so small, but this one is, likely yet another case of miniaturization at the base or transition to a major clade. In this case the SCHA 40 specimen attributed to Leptosaurus (I haven’t seen the holotype) is basal to the much larger Sapheosaurus and Noteosuchus on one branch, Trilophosaurus, Mesosuchus. Priosphenodon and rhynchosaurs on the other.

The large reptile tree (still not updated) keeps adding transitional taxa without changing the tree topology. That’s a measure of its strength. And more taxa using the same number of characters keeps dropping that character/taxon ratio.

References
Renesto S and Viohl G 1997. A sphenodontid (Reptilia, Diapsida) from the late Kimmeridgian of Schamhaupten (Southern Franconian Alb, Bavaria, Germany). Archaeopteryx 15:27-46.

Megachirellla and Marmoretta are basal to Pleurosaurs

Earlier we looked at pleurosaurs (Fig. 1, elongate, aquatic rhynchocephalians). Pleurosaurus goldfussi (Meyer 1831) was discovered first. Palaeopleurosaurus is a more primitive taxon with a distinct premaxillary tooth. Note the retraction of the nares, common to many aquatic reptiles.

The present blogpost updates their origins with phylogenetic analysis, adding these two taxa to the large reptile tree.

Dupret (2004) nested pleurosaurs (Fig. 1) with Sapheosaurus. Adding pleurosaurs to the large reptile tree (not updated yet) nested them with Marmoretta and Megachirella (Figs. 2-5), helping to remove the ‘enigma’ status from the latter. Dupret (2004) did not include these two taxa in analysis.

Figure 1. The pleurosaurs, Pachypleurosaurus and Pleurosaurus, known rhynchocephalians, now nesting with Marmoretta and Megachirella.

Pleurosaurs are yet one more clade of “return to the water” reptiles, and probably the last one anyone thinks of. They’re just not often reported on. Wiki reports, “Pleurosaurus fossils were discovered in the Solnhofen limestone formation of Bavaria, Germany and Canjuers, France.” The limbs were reduced. The torso and tail were elongated. Pleurosaurs probably swam in an eel-like or snake-like undulating pattern.

But where did they come from?

Figure 2. Marmoretta, a basal rhynchocephalian in the lineage of pleurosaurs

Marmoretta oxoniensis (Evans 1991) Middle/Late Jurassic, ~2.5 cm skull length, orginally considered a sister of kuehneosaurs, drepanosaurs and lepidosaurs. Here Marmoretta was derived from a sister to Gephyrosaurus. Marmoretta was a sister to Planocephalosaurus and Megachirella. 

Distinct from Gephyrosaurus, the skull of Marmoretta was flatter overall with a larger orbit. The parietals were longer. The naris was larger and more dorsal. The prefrontal was narrower. The lacrimal was still visible. The jugal was reduced.

A flat-headed rhynchocephalian, Marmoretta nests near the base of that clade, prior to the fusion of teeth together and to the jaws in many derived taxa, including pleurosaurs.

Figure 3. Megachirella, a flat-headed rhynchocephalian close to Marmoretta and basal to pleurosaurs.

Megachirella wachtleri (Renesto and Posenato 2003, Renesto and Bernardi 2013) KUH-1501, 2 cm skull length, Middle Triassic, was a tiny lepidosauromorph with a moderately elongated neck and flattened skull. The teeth were short and stout. Megachirella was originally nested with Marmoretta and the large study confirms it, but it is also basal to the aquatic pleurosaurs.

Figure 4. Megachirella in situ with bones colorized using DGS techniques. Some bones are represented by impressions of the lost bone. The yellow premaxilla tooth is represented by a questionable impression/crack. The nasal may not be a bone, according to S. Renesto. Scale bar = 1 cm.

 

Shifting the pleurosaurs to Gephyrosaurus adds 13 steps. To Planocephalosaurus adds 23 steps. More steps are added with a shift to other rhynchocephalians.

Figure 5. Skull elements of Megachirellla traced in color (Fig. 4) then transferred to line art in three views. Reconstructions are important in such roadkill taxa.

Megachirella is a Middle Triassic rhynchocephalian. That leaves plenty of time for a sister to evolve into a Late Jurassic pleurosaur. The retracted naris common to pleurosaurs is clear on both Marmoretta and Megachirella. All three had an open lateral temporal fenestra.

If you find any mistakes here, please let me know. Such specimens are at or a little beyond the edge of my experience.

References
Carroll RL 1985. A pleurosaur from the Lower Jurassic and the taxonomic position of the Sphenodontids.
Dupret V 2004. The pleurosaurs: anatomy and phylogeny. Revue de Paléobiologie, Geneve 9:61-80.
Evans SE 1991. A new lizard−like reptile (Diapsida: Lepidosauromorpha) from the Middle Jurassic of Oxfordshire. Zoological Journal of the Linnean Society 103:391-412.
Fraser NC and Sues H-D 1997. In the Shadows of the Dinosaurs: early Mesozoic tetrapods. Cambridge University Press, 445 pp. Online book.
Heckert AB 2004. Late Triassic microvertebrates from the lower Chinle Group (Otischalkian-Adamanian: Carnian), southwestern U.S.A. New Mexico Museum of Natural History and Science Bulletin 27:1-170.
Meyer H 1831. IV Neue Fossile Reptilien, aud der Ordnung der Saurier.
Renesto S and Posenato R 2003. A new lepidosauromorph reptile from the Middle Triassic of the Dolomites (northern Italy). Rivista Italiana di Paleontologia e Stratigrafia 109(3) 463-474.
Renesto S and Bernardi M 2013. Redescriptions and phylogenetic relationships of Megachirella wachtleri Renesto et Posenato, 2003 (Reptilia, Diapsida). Paläontologische Zeitschrift, DOI 10.1007/s12542-013-0194-0

Calanguban, another basalmost scleroglossan squamate

Calanguban alamoi (Simoes, Caldwell and Kellner 2014, Early Cretaceous) was originally considered the oldest scincomorph, but in the large reptile tree (not updated yet) it nests with Liushusaurus (Fig. 1) at the base of the Scleroglossa. Due to the large size of its skull and orbit, this was considered an immature specimen. But all sisters are likewise tiny with a large orbit and short rostrum. So what we appear to see hear is yet another case of miniaturization at the base of a major clade.

Earlier we looked at Euposaurus another basal squamate, but at the base of the Iguania.

Figure 1. Liushusaurus (above) and Calanguban (below) to scale. Both nest at the base of the Scleroglossa, which makes them sisters to the basalmost tested iguanid, Iguana. 

References
Evans SE and Wang Y 2010. A new lizard (Reptilia: Squamata) with exquisite preservation of soft tissue from the Lower Cretaceous of Inner Mongolia, China.
Simoes TR, Caldwell MW and Kellner AWA 2014. A new Early Cretaceous lizard species from Brazil, and the phylogenetic postion of the oldest known South American squamates. Journal of Systematic Palaeontology. http://dx.doi.org/10.1080/14772019.2014.947342

wiki/Liushusaurus

Cartorhynchus compared to ichthyosaurs and sauropterygians

While phylogenetic analysis nests the new ichthyosaur-mimic, Cartorhynchus, with pachypleurosaurs, sometimes it helps to put the contenders side-by-side (Fig. 1). I’ve also updated the odd pectoral girdle and traced the visible palatal elements since Cartorhynchus was first presented here (which has been updated).

Figure 1. Sauropterygian sisters to Cartorhynchus (green) compared to ichthyosaurian sister candidates. No ichthyosaurs have a short snout and flat belly. Cartorhynchus and sauropterygians swim with their flippers. All ichthyosaurs swim with their tails. Cartorhynchus nests between Pachypleurosaurus and Qianxisaurus in the large reptile tree. That’s where you find a small premaxilla and large clavicles.

Cartorhynchus certainly has a distinct morphology, even for a pachypleurosaur.  But then pachypleurosaurs are basal to a wide range of marine reptiles including placodonts, plesiosaurs, thalattosaurs (including Helveticosaurus and Vancleavea), ichthyosaurs and mesosaurs.

The large head, short neck and flippers instead of limbs set Cartorhynchus apart from other basal sauropterygians. Placodonts also have a short neck and short rostrum, so it happens.

Like all pachypleurosaurs,
Cartorhynchus has both an anterior and posterior coracoid (Fig. 2) forming a chest shield like a plesiosaur. That makes it a flipper swimmer, not a tail swimmer, like ichthyosaurs, which evolved from long, mesosaur-like sauropterygians, like Wumengosaurus. No ichthyosaur has a flat robust gastralia basket, wide rib cage, and short rostrum like Cartorhynchus and the pachypleurosaurs have. Note the long premaxillary ascending process makes contact withe the frontals, as in Pachypleurosaurus. The palate is more pachypleurosaur-like than ichthyosaur-like.

The scapula-coracoid
In many pachypleurosaurs and their descendants, the anterior coracoid and scapula are fused together. Many illustrations of pachypleurosaurs don’t note this, but call the unit a scapula. You can discover this for yourself by looking at a wide variety of clade members. In Cartorhynchus, the scapula is not fused to the coracoid (Figs. 2, 3).

Figure 1. New tracing and reconstruction of the basal sauropterygian with flippers, Cartorhynchus.

Cartorhynchus and basal ichthyosaurs share many traits.
But Cartorhynchus and basal sauropterygians share a few more. That tips the scales in favor on sauropterygians, based on the hypothesis of maximum parsimony. Ichthyosaurs can also trace their ancestry through basal pachypleurosaurs. So they’re not that far removed.

Figure 2. Cartorhynchus reconstruction in lateral and dorsal views with new lateral view skull and pectoral girdle.

The new palatal data confirms the pachypleurosaur affinities of Cartorhynchus. Note the presence of internal nares essentially below the external nares. In Wumengosaurus and ichthyosaurs the internal nares are set further back in the skull.

The new interpretation of the ultra-wide interclavicle makes the overall shape more fusiform, despite the presence of a small neck, and it locates the scapula as far laterally as the widest ribs, which makes more sense in the reconstruction based on the squared off proximal humerus giving it room to move dorso-ventrally, more like an underwater wing.

References
Motani R et al. 2014. A basal ichthyosauriform with a short snout from the Lower Triassic of China. Nature doi:10.1038/nature13866

DGS: pulling more data out of Eichstaettisaurus gouldi

We’ve looked at DGS (Digital Graphic Segregation) before here, here and here. Today another example, pulling more data from a published photo of a prehistoric reptile crushed flat on an Early Cretaceous matrix. It’s Eichstaettisaurus gouldi (Evans et al. 2004, Figs. 1-7), a pre-snake, which we looked at yesterday.

Figure 1. The hind limb and skull of Eichstaettisaurus gouldi according to Evans et al. 2004.

DGS is a method of tracing the bones (Figs. 2-6), then using the tracings to reconstruct the animal (Fig. 7). On the other hand, by using traditional methods, Evans et al. (2004) produced conventional tracings (Fig. 1).

Figure 2. Eichstaettisaurus gouldi in sintu and traced in color. Here the tail and other bones are identified.

Overall the specimen (Fig. 2) appears to lack most of its dorsal vertebrae and most of its tail. However, using DGS enables these areas to provide data.

Figure 3. Eichstaettisaurus gouldi pes in situ and traced in color. Compare to figure 1. Impressions count in paleontology, not just bones.

Here (Fig. 3) the foot of E. gouldi is traced using colors for digits. Compare this data to the original tracings of Evans et al. (2014, Fig. 1). All of the elements are similar to those in sister taxa. All PILs (parallel interphalangeal lines) are continuous.

Figure 4. Eichstaettisaurus gouldi skull in situ and colorized in ventral view.

Here (Fig. 4) is the skull in ventral view with elements identified (for mandible and palatal bones see below). Rather than a hyoid, as originally tentatively identified, a supratemporal (St) is positively identified here and there’s another one, too. Elements not originally identified include the prefrontal (Prf), postfrontal (Pof), lacrimal (La), nasal (Na), opisthotic, (Op) and supra occipital (So).

Figure 5. Eichstaettisaurus gouldi mandible in situ traced and colorized.

Here (Fig. 5) the mandible elements are digitally segregated. Here teeth are identified. In figure 1 no teeth are identified, but Evans et al. (2004) do note the presence of teeth in the text.

Figure 6. Eichstaettisaurus gouldi palate in situ and colorized. More elements were found here using DGS than by personal examination of the specimen by the three authors, who should have thought it odd that in ventral view so few palatal elements could be identified ten years ago.

Here (Fig. 6) the palate elements are identified using DGS. They are few and far between. Evans et al. only identified the pterygoids, premaxilla and maxilla.

Figure 7. Eichstaettisaurus schroederi. Previous to 2004, the only known specimen of this genus. Proximal carpals are missing here, as they are missing in Adriosaurus.

Eichstaettisaurus schroederi (Fig. 7) has a more generalized (plesiomorphic) shape. The palate can be partly seen within the orbit, and the elements are more robust than in E. gouldi. 

 

Figure 8. Eichstaettisaurus gouldi. A transitional taxon in the lineage of terrestrial snakes. Here all the parts listed above are added to a reconstruction to ensure fit, both mechanically and phylogenetically. The scapula is assumed to have a soft dorsal extension, as in Varanus. The ribs are more slender than phylogenetic bracketing would indicate,  and the coracoids are triangular, the only autapomorphies I’ve found so far. Not sure about neural spines as these are buried in the matrix.

A reconstruction of E. gouldi (Fig. 8) demonstrates the validity of the DGS interpretations as all parts fit both mechanically and phylogenetically. See Varanus, Ardeosaurus, Adriosaurus (Fig. 9) and Pachyrhachis for phylogenetic bracketing. Thus, all the parts are transitional morphologies between varanids and basal snakes. Even the anterior bowing of the radius is found in Adriosaurus.

Figure 8. Various specimens of Adriosaurus documenting the reduction of large clawed hands to small clawless paddles, then ultimately disappearing completely. Note the curved radius and long pedal digits as in E. gouldi.

Eichstaettisaurus gouldi is the first taxon in the lineage of snakes to demonstrate an elongate torso and reduced limbs (though not by very much at this point). These become exaggerated in Adriosaurus and Pachyrhachis.

References
Evans SE, Raia P and Barbera C 2004. New lizards and rhynchocephalians from the Lower Cretaceous of southern Italy. Acta Palaeontologica Polonica 49:393-408.

Not Bavarisaurus?

Conrad (2014) reports
The lizard ingested by Compsognathus  (Fig. 1) is a new species, not congeneric with the holotype of Bavarisaururus macrodactylus (= Homoeodactylus macrodactylus, Wagner 1852). That is verified here.

Figure 1. Click to enlarge. The little Jurassic lizard Bavariasaurus was found inside the belly of the little Jurassic dinosaur, Compsognathus. But it is not the same genus as the holotype.

From the Conrad (2014) abstract:
“Bavarian limestone deposits represent some of the few areas preserving articulate Jurassic squamates. Bavarisaurus, two species of Eichstaettisaurus, and Ardeosaurus have been recognized from those deposits. Although usually identified as Bavarisaurus macrodactylus or Bavarisaurus cf. macrodactylus, a lizard preserved as a cololite in the theropod Compsognathus longipes shows important differences from the type specimen of Bavarisaurus macrodactylus. This cololite lizard specimen (hereafter, ‘cololizard’) is preserved as a combination of bone and bone-impressions, some of which are extremely clear. The skull preserves the premaxilla, maxilla, prefrontal, frontal, parietal, postfrontal, jugal, pterygoid, ectopterygoid, and mandible. The humerus and much of the thoracic skeleton, tail, pelvis, and hind limb are preserved. Comparative studies demonstrate that the ingested form is a new species. A cladistic analysis of 133 fossil and living lepidosaurs scored for 1318 morphological characters suggests that Eichstaettisaurus gouldi and Bavarisaurus macrodactylus are sister species.

“Eichstaettisaurus schroederi and the cololizard form a polytomy with that clade in an holophyletic Eichstaettisauridae with the unambiguous synapomorphies of paired premaxillae, angulated jugals, and presence of a hook-like postglenoid humeral process. Eichstaettisaurus gouldi and Bavarisaurus macrodactylus are united by the shared presence of a straight frontoparietal suture. The cololizard differs from Bavarisaurus macrodactylus in possessing an anteriorly arching (rather than a W-shaped) frontoparietal suture, a fused (unpaired) parietal, and anteroposteriorly-oriented parietal supratemporal processes. The cololizard differs from Eichstaettisaurus schroederi in possessing a weakly inclined maxillary nasal process, an anteroposteriorly elongate (rather than tall)prefrontal, a longer prefrontal orbital process, absence of cristae cranii, and an anteriorly arched (rather than transverse) frontoparietal suture. The cololizard will soon be named as a type specimen within the type specimen for Compsognathus, and further expands known Jurassic Bavarian lizard diversity.”

Figure 2. Click to enlarge. Cleaned up reconstruction of the former Bavarisaurus (cololizard at present). Gray areas added based on sister taxa. This is a tritosaur.  Note the large naris bounded ventrally by the maxilla. The ventral pelvis is shallower. I don’t understand the pterygoid morphology anteriorly. The upper and lower teeth don’t match. That’s a red flag, but it is the only data available.

Homoeosaurus? macrodactylus holotype
The holotype of Bavarisaurus/Homoeosaurus? macrodactylus (Wagner 1852, Fig. 3) is indeed different than the ingested lizard (Fig. 1, Nopcsa 1903, Hoffstetter 1964).

Figure 3. Homoesaurus/Bavarisaurus? macrodactylus actually nests with Huehuecuetzpalli, so the lizard inside Compsognathus is indeed different.

Figure 3. Eichstaettisaurus schroederi is considered by Conrad to be a sister to the ingested lizard, but it doesn’t appear to share many traits as far as I can tell, and phylogenetic analysis confirms this. Eichstaettisaurus actually nests basal to Adriosaurus and snakes.

No one should know lizards better than Conrad
whose 2008 paper tested 222 fossil and extant taxa with 363 character traits. Unfortunately that phylogeny: (1) failed to find a third lepidosaur clade; (2) nested snakes with amphisbaenians (legless traits must have swamped out other traits); (3) failed to find the diphyletic origin of snakes, but nested the highly derived Leptotyphlops at the base; (4) nested the pre-snake Adriosaurus with mosasaurs; and (5) failed to recover the Eichstaettisaurus / Ardeosaurus link with Adriosaurus and snakes. Otherwise, the tree looked pretty good.

The large reptile tree nests the ingested lizard in the middle of the Tritosauria. The tree nests the holotype of Homoeosaurus macrodactylus with Huehuecuetzpalli, not with Homoeosaurus solnhofensis. The tree nests Eichstaettisaurus with Ardeosaurus close to Adriosaurus, the ancestor of terrestrial snakes.

References
Conrad J 2008. Phylogeny and systematics of Squamata (Reptilia) based on morphology. Bulletin of the American Museum of Natural History 310:1-182.
Conrad J 2014. The lizard (Squamata) in Compsognathus (Theropoda) is a new species, not Bavarisaururus. Journal of Vertebrate Paleontology abstracts.
Hoffstetter R 1964. Les Sauria du Jurassique supérieur et specialement les Gekkota de Baviére et de Mandchourie. Senckenberger Biologische 45, 281–324.
Nopcsa F 1903. Neues ueber Compsognathus. Neues Jahrbuch fur Mineralogie, Geologie und Palaeontologie 16: 476-494.
Wagner A 1852. Neu-aufgefundene Saurier, Uberreste aus dem lithographischen Schiefern und dem obern Jurakalke: Abhandlungen der Bayerischen Akademieder Wissenschaften Mathematisch-naturwissenschafliche Kl, 3(6): 661-710.