Gemuendina stuertzi (named for Gemünden from where it was discovered)[1] is a placoderm of the order Rhenanida, of the seas of Early Devonian Germany. In life, Gemuendina resembled a scaly ray with an upturned head, or a large-finned stargazer. G. stuertzi is often invoked as an example of convergent evolution- with its flat body and huge, wing-like pectoral fins it has a strong, albeit superficial similarity to rays. Unlike rays, however, both Gemuendina`s eyes and nostrils were placed atop the head, facing upward. Furthermore, G. stuertzi's upturned mouth would have enabled it to suction prey that swam overhead, rather than swallow sediment or suction prey out of the substrate like modern rays.
Gemuendina stuertzi reconstructionModel of Gemuendina at AMNH
Unlike most other placoderm orders, such as the Antiarchs, or the Arthrodires, Gemuendina and its four other known relatives (or seven, if the three species of the ichthyolith genus Ohioaspis are confirmed to be rhenanids) had armor made up of a mosaic of unfused bony plates and scales. Because their armor was so fragile, few intact examples of rhenanids have survived in the fossil record. Because several regions of the Hunsrucklagerstätte were anoxic, thus free of scavenging organisms, intact, nearly pristine (albeit flattened) specimens of G. stuertzi have been found as a result. Also unlike other placoderms, it did not have the characteristic tooth plates of placoderms. Instead, it had star-shaped tubercle scales that allowed it to seize, then swallow fish and other animals that swam too close with its mouth.
Specimens of G. stuertzi ranged in size from 30 to 100 centimeters in length. In 1971, Erik Stensiö described a metre long specimen as a new species, "Broilina heroldi," which was later synonymized with Gemuendina.
Referencesedit
^Traquair, R.H. (1903). The Lower Devonian Fishes of Gemünden. Edinburgh: Edinburgh : Royal Society of Edinburgh. p. 723.
Janvier, Philippe. Early Vertebrates Oxford, New York: Oxford University Press, 1998. ISBN0-19-854047-7
Long, John A. The Rise of Fishes: 500 Million Years of Evolution Baltimore: The Johns Hopkins University Press, 1996. ISBN0-8018-5438-5
gemuendina, stuertzi, named, gemünden, from, where, discovered, placoderm, order, rhenanida, seas, early, devonian, germany, life, resembled, scaly, with, upturned, head, large, finned, stargazer, stuertzi, often, invoked, example, convergent, evolution, with,. Gemuendina stuertzi named for Gemunden from where it was discovered 1 is a placoderm of the order Rhenanida of the seas of Early Devonian Germany In life Gemuendina resembled a scaly ray with an upturned head or a large finned stargazer G stuertzi is often invoked as an example of convergent evolution with its flat body and huge wing like pectoral fins it has a strong albeit superficial similarity to rays Unlike rays however both Gemuendina s eyes and nostrils were placed atop the head facing upward Furthermore G stuertzi s upturned mouth would have enabled it to suction prey that swam overhead rather than swallow sediment or suction prey out of the substrate like modern rays GemuendinaTemporal range Emsian Fossil of Gemuendina stuertzi at the American Museum of Natural History Scientific classification Domain Eukaryota Kingdom Animalia Phylum Chordata Class Placodermi Order Rhenanida Family Asterosteidae Genus GemuendinaTraquair 1903 Species G stuertzi Binomial name Gemuendina stuertziTraquair 1903 Synonyms Broilina heroldi Stensio 1971 Gemuendina stuertzi reconstruction Model of Gemuendina at AMNH Unlike most other placoderm orders such as the Antiarchs or the Arthrodires Gemuendina and its four other known relatives or seven if the three species of the ichthyolith genus Ohioaspis are confirmed to be rhenanids had armor made up of a mosaic of unfused bony plates and scales Because their armor was so fragile few intact examples of rhenanids have survived in the fossil record Because several regions of the Hunsruck lagerstatte were anoxic thus free of scavenging organisms intact nearly pristine albeit flattened specimens of G stuertzi have been found as a result Also unlike other placoderms it did not have the characteristic tooth plates of placoderms Instead it had star shaped tubercle scales that allowed it to seize then swallow fish and other animals that swam too close with its mouth Specimens of G stuertzi ranged in size from 30 to 100 centimeters in length In 1971 Erik Stensio described a metre long specimen as a new species Broilina heroldi which was later synonymized with Gemuendina References edit Traquair R H 1903 The Lower Devonian Fishes of Gemunden Edinburgh Edinburgh Royal Society of Edinburgh p 723 Janvier Philippe Early Vertebrates Oxford New York Oxford University Press 1998 ISBN 0 19 854047 7 Long John A The Rise of Fishes 500 Million Years of Evolution Baltimore The Johns Hopkins University Press 1996 ISBN 0 8018 5438 5External links edit nbsp Paleontology portal Paleos Rhenanida nbsp This article about a placoderm is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Gemuendina amp oldid 1211547506, wikipedia, wiki, book, books, library,
