Gemuendina stuertzi

Taxobox
name = "Gemuendina"

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fossil_range = Early Devonian
regnum = Animalia
phylum = Chordata
classis = Placodermi
ordo = Rhenanida
familia = Asterosteidae
genus = "Gemuendina"
species = "G. stuertzi"

"Gemuendina stuertzi" ("Stuertz's Gemünden (fish)") was an early placoderm species of the order Rhenanida, of the seas of Early Devonian Germany. "Gemuendina" resembled a scaly ray with a pair of staring eyes, a pug-nose, and an upturned mouth. This leads virtually all artists who reconstruct it to give the creature a quizzical, almost shocked expression. It is a good example of convergent evolution- with its flat body and huge, wing-like pectoral fins it is highly similar to rays. Unlike rays, both "Gemuendina"`s eyes and nostrils were placed atop the head. Unlike most other placoderms, such as the Antiarchs, or the Arthrodires, "Gemuendina" and its three other known relatives (six, if the species of "Ohioaspis" are considered to be rhenanids) had armor made up of a mosaic of unfused bony plates. Because their armor was so fragile, few examples of rhenanids have survived in the fossil record. Because several regions of the Hunsruck lagerstätte 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.

External links

* [http://www.palaeos.com/Vertebrates/Units/Unit060/060.100.html#Rhenanida "Paleos Rhenanida"]

References

* 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 0-8018-5438-5