Atractosteus


Atractosteus, 'spindle' and osteon is a genus of gars in the family Lepisosteidae, with three extant species. It is one of two surviving gar genera alongside Lepisosteus.
The three surviving species are all widely separated from one another, with A. spatula being found in the south-central United States, A. tropicus in southern Mexico and Central America, and A. tristoechus in Cuba. Although generally inhabiting fresh water, they are tolerant of marine conditions.

Evolution

The genus first appeared during the Santonian stage of the Late Cretaceous, having diverged from Lepisosteus earlier in the Cretaceous. It quickly achieved a widespread distribution throughout the rest of the Cretaceous, being known from North America, South America and Europe. Atractosteus survived the Cretaceous-Paleogene extinction event, with one articulated fossil of the species A. grandei being recovered from strata dated to just a few thousand years after the extinction event, making it the oldest known articulated vertebrate fossil from the Cenozoic. It was found throughout North America and Europe during the Paleogene, but by the Neogene this had shrunk to only certain parts of North America, where it is still found today.

Systematics

Species

Fossil species

The following fossil species are known:
Former fossil species:

Dubious fossil species

  • †"Atractosteus" africanus
  • †"Atractosteus" emmonsi Hay 1929
  • †"Atractosteus" lapidosus Hay 1919
  • †Atractosteus occidentalis non Wiley 1976
The extinct nomen dubium fossil species A. strausi is based on a single Miocene-aged gar scale from Germany, and has often been used as the species for the Atractosteus gars from the older Messel Formation. Although this scale provides evidence for gars surviving in Europe as late as the Miocene, it is not diagnostic enough to be considered a member of Atractosteus, nor can the Messel gars be confidently placed in it.