Deinodus
Encyclopedia
Deinodus is a form genus that includes two species: the form found in the Onondaga Formation of western New York
, Deinodus bennetti, and the form found in the Columbus and Limestone of central Ohio
, Deinodus ohioensis. Both species are limited to the Eifelian age of the middle Devonian
Period, which occurred 398-391 million years ago (Martin, 2002).
Denison (1978) postulates that the genus could be an arthrodire or ptyctodont, but places it in his "incertae sedis
" section. Individual specimens tend to resemble the ptyctodonts from the same units and ptyctodonts from Australia
, so Deinodus is most likely a ptyctodont. Specimens interpreted as lateral spines may show that Deinodus was a basal ptyctodont, not far removed from the petalichthids
(Martin, 2002).
D. bennetti was first described in 1919 (Hussakof and Bryant). Specimens of Deinodus exhibit a variety of shapes, though most possess the characteristic large tubercles reported by Hussakof and Bryant (1918). Those specimens that do not possess tubercles resemble those that do possess tubercles. These tubercles are usually found on a margin, close to the widest point, and are different in appearance from those reported in other placoderms (Long, 1997).
The variety of shapes probably represents function rather than ontogeny
. Specimens have been attributed to upper and lower dental plates, dorsal spines, trunk shield plates and lateral spines. Tubercles are found on all of these elements (Long, 1997; Martin, 2002).
Most specimens that are considered dental elements are still entombed in matrix, so it is difficult to determine the feeding strategy of the fish (Martin, 2002). Since most ptyctodonts are durophagus
(Maisey, 1996), meaning that they ate organisms with hard shells or exoskeletons, it seems likely that Deinodus was too.
D. ohioensis was a bit smaller than D. bennetti and preferred shallower water. D. ohioensis could have been a smaller species or juvenile D. bennetti using the Columbus sea as a nursery area (Martin, 2002).
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
, Deinodus bennetti, and the form found in the Columbus and Limestone of central Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...
, Deinodus ohioensis. Both species are limited to the Eifelian age of the middle Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
Period, which occurred 398-391 million years ago (Martin, 2002).
Denison (1978) postulates that the genus could be an arthrodire or ptyctodont, but places it in his "incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
" section. Individual specimens tend to resemble the ptyctodonts from the same units and ptyctodonts from Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, so Deinodus is most likely a ptyctodont. Specimens interpreted as lateral spines may show that Deinodus was a basal ptyctodont, not far removed from the petalichthids
Petalichthyida
The Petalichthyida was an order of small, flattened placoderm fish. They were typified by their splayed fins, and numerous tubercles that decorated all of the plates and scales of their armor. They reached a peak in diversity during the Early Devonian and were found throughout the world,...
(Martin, 2002).
D. bennetti was first described in 1919 (Hussakof and Bryant). Specimens of Deinodus exhibit a variety of shapes, though most possess the characteristic large tubercles reported by Hussakof and Bryant (1918). Those specimens that do not possess tubercles resemble those that do possess tubercles. These tubercles are usually found on a margin, close to the widest point, and are different in appearance from those reported in other placoderms (Long, 1997).
The variety of shapes probably represents function rather than ontogeny
Ontogeny
Ontogeny is the origin and the development of an organism – for example: from the fertilized egg to mature form. It covers in essence, the study of an organism's lifespan...
. Specimens have been attributed to upper and lower dental plates, dorsal spines, trunk shield plates and lateral spines. Tubercles are found on all of these elements (Long, 1997; Martin, 2002).
Most specimens that are considered dental elements are still entombed in matrix, so it is difficult to determine the feeding strategy of the fish (Martin, 2002). Since most ptyctodonts are durophagus
Durophagy
Durophagy is the term for describing the eating behavior of animals that consume hard-shelled or exoskeleton bearing organisms, such as corals, shelled mollusks, or crabs....
(Maisey, 1996), meaning that they ate organisms with hard shells or exoskeletons, it seems likely that Deinodus was too.
D. ohioensis was a bit smaller than D. bennetti and preferred shallower water. D. ohioensis could have been a smaller species or juvenile D. bennetti using the Columbus sea as a nursery area (Martin, 2002).