A Re-Evaluation of the Pleistocene Hellbender, Cryptobranchus guildayi
Cryptobranchus guildayi has been described as an extinct species of large salamander that is related closely to the modern Hellbender, Cryptobranchus alleganiensis. The validity of this extinct taxon has been questioned; thus, an expanded osteological sample of modern Hellbenders was compared to the C. guildayi fossil material. Based on our analysis of the fossil material, all morphological characters used to define C. guildayi can be observed in specimens of C. alleganiensis, or are based on misidentifications. Therefore, C. guildayi is considered to be conspecific with C. alleganiensis and taxonomically should be considered a junior synonym of the latter. The reassignment of the C. guildayi specimens to C. alleganiensis expands the prehistoric geographical range of the modern species to the Potomac River and its tributaries and also extends the age of the species into the Irvingtonian North American land mammal age.Abstract
A) Cryptobranchus guildayi fossil holotype used for original diagnosis of the species, a left partial dentary in lingual view (CM 20470); B) fossil dentary attributed to C. guildayi in the amended species diagnosis, in occlusal view (CM 40416); C) modern Cryptobranchus alleganiensis right dentary, in occlusal view (DCP 661).
Fossil sacral rib (CM 40416) attributed to Cryptobranchus guildayi and previously identified as a hyoid element in the species' amended diagnosis in A) lateral view (the arrow indicates the damaged region), and B) articular view; C) a modern Cryptobranchus alleganiensis sacral rib in lateral view in articulated life position (anterior is to the right; ETVP 6917); D) a modern C. alleganiensis sacral rib in articular view (DCP 661).
Bivariate plot of Cryptobranchus alleganiensis trunk vertebrae dimensions, with best fit regression (solid line) and 95% confidence interval (dashed lines). GWZ = the greatest width through the zygopophyses; GLZ = the greatest length through the zygopophyses.
Contributor Notes
