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.
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.”
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).
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.
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.