Echinochimaera
Name:
Echinochimaera
(Spiny chimaera).
Phonetic: Ek-in-o-ky-me-rah.
Named By: Richard Lund - 1977.
Classification: Chordata, Chondrichthyes,
Holocephali, Chimaeriformes.
Species: E. meltoni
(type), E. snyderi.
Diet: Uncertain.
Size: E. meltoni males up to
15 centimetres
long, females 7 centimetres. E. snyderi
only known from
juveniles at the time of writing, but analysis suggests slightly
larger than E. meltoni when fully grown.
Known locations: USA, Montana.
Time period: Serpukhovian of the Carboniferous.
Fossil representation: Numerous individuals
including juvenile specimens.
Though
only small, Echinochimaera is still a very
interesting fish that is
known to have swum in the waters of what is now Montana during the
Carboniferous. Echinochimaera had a deep round
body that was
propelled by a relatively thin tail which ended in a small caudal fin.
This indicates that Echinochimaera was not a very
fast swimmer, and
as such may have cruised along in slower waters. Sexual dimorphism
seen in the type species is quite extreme with males of E.
meltoni
growing to just over double the size of the females. At the time of
writing E. snyderi is only known from juveniles,
but comparison to
similarly aged juveniles of E. meltoni suggest
that E. snyderi
would have been the larger species when fully grown.
Strong
spines supported the fins, and while these may have provided support
for them when brushing past submerged debris, as well as provided
some defence against predators, they may have also served a display
function. Indeed the males of E. meltoni had a
differently shaped
dorsal fin to the females, with the main spike being larger and
pointing forwards. Males also had four pairs of spines on top of
their heads whereas females only had one pair.
Further reading
- Chondrichthyan life history styles as revealed by the 320
million years old Mississippian of Montana. - Environmental
Biology of Fishes (Springer Netherlands) 27 (1): 1–19. -
Richard Lund - 1990.
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