Gavialosuchus americanus

The false gharials, a type of crocodylian, were widespread throughout the world during the Miocene between 25 million years BP- 5 million years BP.  They inhabited the coastal regions of Eurasia, and North and Central America when worldwide climate was warmer than it is today.  With their long snouts and rows of sharp teeth, they were well adapted for catching the fish that abounded in salt marshes and saltwater lagoons.  Fossil evidence of false gharials has been found along the eastern seaboard of North America from Florida to as far north as New Jersey.  Gaviolosuchus americanus is the species that lived in eastern North America during the late Miocene, while G. carolinensis occurred here during the Oligocene (33 million years BP- 25 million years BP).  The false gharials likely arose as early as the Eocene.

New Pictures 026

Skeleton of Gavialosuchus carolinensis on display at the Charleston Museum.  This species lived during the Oligocene.

Gavialosuchus americanus Skull

Skull of Gavialosuchus americanus.  Note the long snout.

Some scientists use the scientific name of Thecachampus americanus instead of Gavialosuchus americanus.  Scientific nomenclature is a tedious topic, so I won’t delve too deeply into it on my blog.  The first scientific name ever given to a species holds precedence.  Paleontologists often find fossil material they mistakenly think is from a new species, and they will give it a name.  Later studies then determine the “new” species is actually the same as a species that had already been named.  The older species name is accepted as the correct one.  The dispute between the usage of Gavialosuchus americanus and Thecachampus americanus has yet to be unanimously resolved.

Gavialosuchus americanus was a little larger than the sole surviving species of false gharial–Tomistoma schlegeli.  The extinct species grew to 18 feet, surpassing T. schlegeli by a couple of feet.  T. schlegeli survives today in parts of Malaysia and Indonesia, but they’ve been extirpated from Thailand.  They mostly eat fish but will opportunistically take monkeys, deer, birds, other reptiles, and humans.

Tomistoma schlegelii false gharial LA zoo 03.jpg

The only species of false gharial still extant–Tomistoma shlegeli.  Various species  of false gharials occurred along the coasts  of Eurasia and North America  from the late Eocene to the early Pliocene.

Anatomical studies suggested the false gharials are distantly related to the true gharial (Gaviatis gangetives) of India.   The long narrow snout of the false gharial was considered an example of convergent evolution when unrelated or distantly related organisms evolve the same adaptation to similar environments.  However, a genetic study determined the false gharial and the true gharial are closely related sister species.  The vertebrate zoologists were wrong.

Gavialosuchus americanus co-existed with a species of alligator in North America.  An analysis of chemical isotopes in the bones of both crocodylians suggests they occupied different habitats.  The false gharial of America inhabited saltwater environments and alligators ruled the freshwater lakes and streams.

References:

Harshman, J. ; et. al.

“True and False Gharials: A Nuclear Genophylogeny of Crocodylians”

Systematic Biology 2003

Whiting, Evan; David Steadman, and John Krigbow

“Paleoecology of Miocene Crocodylians in Florida: Insights from Stable Isotope Analysis”

Paleogeography, Paleoclimatology, Paleoecology March 2016

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