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.

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.

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

Figure 3. Eichstaettisaurus schroederi.

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.

 

2 thoughts on “Not Bavarisaurus?

  1. Figures 2 and 3 in Nopcsa’s plate are the braincase of Compsognathus itself as preserved (2) and reconstructed (3), not the lizard’s. Thus the “pterygoid morphology anteriorly” is the cultriform process and basipterygoid processes of a theropod.

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