Heteropetalus elegantulus
Female Heteropetalus elegantulus fossil.
Heteropetalus elegantulus is an elegantly slim little euchondrocephalan with many different tooth shapes along its jaws. It ranges to only about 4 inches in length. Skull, jaws, and dentition place it close to Debeerius. It is common in the weedier shallow water areas.
Male (top) and female (bottom).
There are no scales, except for a small patch at the rear of the dorsal fin of males. Lateral line canals of the head are supported by rather large highly modified scales. Heteropetalus has an almost eel-like body, a protocercal tail, rounded and very flexible pectoral fins midway up the sides of the body, and a single long flexible undulatory dorsal fin (preceded by a small fin spine). All these features indicate a maneuverer in weedy or reef-like environments as well as along the bottom.
Mature males have a distinctly strengthened, hooked and denticulated posterior end of the dorsal fin; the dorsal fin of males was significantly higher than that of females. This dorsal fin dimorphism is similar to that seen in the Gouramies, modern bony tropical fish available in any pet store.
Dorsal view of Heteropetalus elegantulus head
They have a very small mouth, with the teeth crowded to the front of the jaws, and a variety of plucking, nipping, and crunching teeth. The jaw suspension itself is rather flexible to give it a certain amount of both lateral and fore-and-aft motion.
The bright yellow spots in the dorsal view of a head are the inner
ears, and the yellow is from iron oxide particles that were
bio-concentrated during the life of this fish.
H. elegantulus was
originally described as a petalodont, but subsequent discoveries proved
it to be otherwise; it is closely related to Debeerius ellefseni.
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