Make way
for Bothriolepis rex, a bottom-feeding fish from the Devonian that represents
the biggest of its kind.
A
multi-institution team of researchers has discovered the newest, biggest member
of a group of extinct, armor-plated fish called Antiarchi.
The new
fish, Bothriolepis rex, dates to the Devonian Period, some 370 million years
ago, and swam Earth's oceans long before dinosaurs were on the scene. Bony
plates covered its front fins, shoulders and head, and its size – about 5.5
feet long – makes it the new top fish among Antiarchs, surpassing Bothriolepis
maxima by about 30% in length.
Researchers
from Drexel University, Delaware Valley University, Stanford University and the
University of Chicago collaborated on the discovery and have published their
findings about the ancient fish in the Journal of Vertebrate Paleontology.
The fossils
used to describe the fish were found on Ellesmere Island in Nunavut, Canada and
included the bony, thick plates that covered the ancient creature's head. The
plates probably gave B. rex a measure of protection from the bites of large
predatory fish called sarcopterygians, say the researchers.
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The fish
wasn't the violent type. It may have a "rex" in its name, but B. rex
was no kind of fierce hunter. Instead, the scientists say, it was, like others
in the Bothriolepis genus, a bottom-feeder that cruised the sandy sea floor
picking up dead plant and animal matter.
With a
flattened underside and a downward-angled mouth, "it was not equipped for
active predation," said the study's lead author Jason Downs, of Delaware Valley
University, in a statement.
Bones from
the skull of Bothriolepis rex and a line drawing of the head viewed from above.
The bones create an armor with a single opening for the eyes. The mouth is on
the lower surface of the skull, indicating a bottom-feeding life. Photo by
Valentina Garcia,drawing by Jason Downs.
"Bothriolepis
rex extends the range of known body sizes for the group Antiarchi," said
Downs. "The large body size and the thick, dense armor present a unique
opportunity to address questions about the lifestyle of this unusual group of
armored swimmers."
Armor
aside, however, the party would "soon" end for B. rex, whose size
might not have helped its cause.
"All
Antiarchs are extinct by the end of the Devonian Period," said Downs.
"We can't know exactly why B. rex went extinct, but large-bodied species
are often found to be at a higher risk of extinction than small-bodied
ones."
