Rhacolepis buccalis Prehistoric Fossil Fish Osteichthyes Bony Fish Cretaceous Collection (3)

Description

Origin : Santana Formation, Cearà (Brazil)

Geological era : Early Cretaceous (Albian)

Age : 110 million of years

Size : cm 11.3 x 4.3 x 2.5

Prehistoric Fossil Fish Rhacolepis buccalis cm 11.3 x 4.3 x 2.5 Osteichthyes Extinct Bony Fish Mesozoic Cretaceous Collecting Paleontology Museum.

Nice collectible fossil find of good quality, with  appreciable details of the scales and, unusually, of the caudal fin, which often does not remain preserved. From the fossiliferous deposits of Santana Formation, Ceará, Brazil, only a piece, as in photo.
For supports, see Equipment Catalog

Rhacolepis buccalis is an extinct bony fish belonging to the Crossognatiformes. It lived in the Lower Cretaceous (Albian, about 115 - 105 million years ago) and its fossil remains were found in Brazil.
This robust-bodied fish could reach a length of about 25 centimeters. The head was long with a tapered anterior margin, and was about 33% of the length of the body. The paired fins were short; the pelvic fins originated from behind the level of the dorsal fin. The scales along the body were deeper than long and overlapped each other; they were rather small, ovoid, characterized by circles on the dorsal and ventral surfaces, and extended to the base of the fins.
Rhacolepis was characterized by a ploughshare equipped with two curved teeth and a single row of pointed teeth.
A 2016 study on two specimens of Rhacolepis demonstrated the possibility of fossilization of the heart in these fish. Rhacolepis in fact had a heart with an arterial cone equipped with at least five rows of valves. This represents a transitional morphology between the primitive many-valve condition and the current derived, single-valve condition. These fossils would demonstrate that the simplification of the heart in modern actinopterygia occurred gradually, and not through a drastic event.
Rhacolepis buccalis was described for the first time in 1841 by Louis Agassiz, in the monumental work Recherches sur les Poissons Fossiles. Rhacolepis fossils come mainly from the Santana Formation of the Albian of northeastern Brazil. Many of these fossils were found in nodules, in which the details were perfectly preserved.
Rhacolepis was initially attributed to elopids, but subsequent research indicated that this animal was a member of the pachyrizodontids, a group of fast predatory fish typical of the Cretaceous. The related, more recent Pachyrhizodus was much larger in size. Rhacolepis and the pachyrizodontids (included in the crossognatiformes group) may be closely related to the elopomorphs (Elopomorpha) and would appear to occupy a basal position among modern teleosts. Due to its phylogenetic position, Rhacolepis is fundamental for studies on the evolution of the morphological characteristics of teleosts.