Lanarkia
horrida Thelodont
Phylum
Chordata, Subphylum Vertebrata, Superclass Agnatha, Group Thelodonti
(Thelodontiformes)
Geological
Time: Upper Silurian
Size: 45
mm in length
Fossil Site:
Seggholm, Muikirk, Ayrshire, Scotland
The
Thelodontia are a group of fishes most commonly known from their
distinctive tooth-like scales. Indeed the term Thelodont, derived
from Greek, means nipple tooth. The teeth have a characteristic
crown made
of dentine. The scales even on a single specimen are quite variable.
Thelodonts are rarely found as complete specimens; those that are
show them to be flattened fish, many of which were bottom dwellers.
Recent finds of intact specimens from Canada show that thellodonts
evolved into some deep-bodied forms that swam freely in the water
column. These deep-bodied forms may have been more closely allied
with jawed fishes than their other relatives. All Thelodonts were
extinct by the Upper Devonian. This high-quality specimen exhibits
the distinctive, chracteristic scales.
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