Echinochimaera

Ek-in-o-ky-me-rah.
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John Stewart

Paleoecologist

John Stewart is a distinguished paleoecologist whose work has significantly advanced our understanding of prehistoric ecosystems. With over two decades dedicated to unearthing fossils across Asia and Africa

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Name

Echinochimaera ‭(‬Spiny chimaera‭)‬.

Phonetic

Ek-in-o-ky-me-rah.

Named By

Richard Lund‭ ‬-‭ ‬1977.

Classification

Chordata,‭ ‬Chondrichthyes,‭ ‬Holocephali,‭ ‬Chimaeriformes.

Diet

Uncertain.

Species

E.‭ ‬meltoni‭

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.

In Depth

       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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