Two new North American Alligatorids discovered in 2020

[Crocophile]

Two new species of Alligatorids were discovered this year, one in Florida, another in Texas. The one from Florida seems to bridge the extinct A. mefferdi, to the extant A. mississippiensis, sharing characteristics of both.

 

1. Alligator hailensis

New early Pleistocene Alligator (Eusuchia: Crocodylia) from Florida bridges a gap in Alligator evolution

ABSTRACT: The American Alligator (Alligator mississippiensis) is one of two species of Alligator in the modern world. It is only distantly related to the other extant species (A. sinensis), with much closer relatives known from the geologic past of North America. A disparity exists, though, in the fossil record between A. mississippiensis and its close relative, the late Miocene (?)—early Pliocene A. mefferdi. While A. mississippiensis is known from the mid-Pleistocene and later, few Alligator remains were known from the earliest Pleistocene of North America until the discovery of the Haile 7C and 7G early Pleistocene (Blancan Land Mammal Age) sites from Alachua County, Florida. The Haile alligators exhibit a suite of characters from both A. mississippiensis and A. mefferdi, displaying intermediate morphology in time. The Haile alligators are distinct from either of the aforementioned taxa, and a new species, Alligator hailensis is suggested, bridging an important gap in the evolution of the American Alligator.

https://www.biotaxa.org/Zootaxa/article/view/zootaxa.4868.1.3

 

Image below of Alligator hailensis is by Jeremy B. Stout. Creative Commons 4.0 (CC By.SA.4.0)

 

2. Bottosaurus fustidens

 

A new species of Bottosaurus (Alligatoroidea: Caimaninae) from the Black Peaks Formation (Palaeocene) of Texas indicates an early radiation of North American caimanines

 

ABSTRACT: Morphological and molecular data suggest a close relationship for alligators and caimans. The first fossil appearances combined with phylogenetic hypotheses suggest a divergence of the groups near the Cretaceous–Palaeogene boundary, but the early fossil record of Caimaninae is incomplete, and large gaps exist between the earliest representatives of the group. A new caimanine from lower Palaeocene (Tiffanian) deposits in the Black Peaks Formation of Brewster County, Texas is established upon two specimens of different size that bear similarities to Bottosaurus harlani from the uppermost Cretaceous and lowermost Palaeogene of New Jersey. The larger individual consists of a partial skull and lower jaw in addition to postcranial material. The smaller individual preserves a snout and posterior portions of the skull. Both specimens suggest an animal with a comparatively short, flat, broad snout. Species of Bottosaurus share diagnostic morphological character states but are differentiated in meaningful ways. Phylogenetic analysis shows that the new species is sister to B. harlani, indicates an early radiation of North American caimanines and elucidates a more complicated biogeographical history than previously hypothesized. A growing body of evidence suggests that Caimaninae may be diagnosed by ancestral characters, potentially drawing basal alligatoroids crownwards in phylogenetic trees.

https://academic.oup.com/zoolinnean/article-abstract/191/1/276/5815831

 

[digit]

Very interesting. I need to track down a copy of the Haile alligator. I work with late Miocene gators from the Montbrook site on a nearly daily basis so this new "missing link" should make for interesting reading.

 

 

Cheers.

 

-Ken