The centra appear to become longer anteriorly, with amphicoelous
The centrum bears an amphicoelous
condition, concave anterior and posterior articular facets.
In addition, in the Deccan Intertrappean beds, no single amphicoelous
or opisthocoelous vertebra has been reported, and all available vertebral specimens appear to belong to procoelous Neobatrachia, an anuran clade that includes taxa more derived than discoglossids (PRASAD & RAGE, 2004).
Overall, the Clark Quarry vertebrae display a suite of features that characterize Amphiuma as follows (modified from Holman, 11, 13, and Gardner, 7): vertebrae elongate and amphicoelous
; neural crests long and well developed; neural spines short and divergent from either side of the posterior extent of the neural crests; postzygapophyseal crests present (worn but evident in the fossils); alar processes present (damaged on the fossils); transverse processes broken but appear to be unicapitate suggesting a post-anteriormost trunk position; centra constricted medially with deep subcentral keels (evident but worn or damaged in both fossils); anterior basapophyses elongate (preserved in GCVP 8310 but damaged in GCVP 8311).
The platycoelous centra recognized in UPUAM 14072 allow to exclude its assignment to the European pachypleurosaurs, which present amphicoelous
centra and pachyostotic zygapophyses (Rieppel, 2000).
vertebra), the posterior face more so.
All the preserved vertebrae are clearly amphicoelous
, with the centrum circular, ventrally concave and as high as broad.
All the centra are platycoelous or slightly amphicoelous
with hexagonal articular surfaces.