| Stensioella | |
|---|---|
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| Cast of specimen fromHunsrück,Budenbach,Germany. | |
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| Reconstruction | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | †Placodermi |
| Order: | †Stensioellida Romer, 1945 |
| Family: | †Stensioellidae Berg, 1940 |
| Genus: | †Stensioella Broili, 1933 |
| Species: | †S. heintzi |
| Binomial name | |
| †Stensioella heintzi Broili, 1933 | |
Stensioella heintzi is an enigmaticplacoderm of arcane affinity. It is only known from theLower DevonianHunsrück slate of Germany. Thegenus is named afterErik Stensiö, the species name honoursAnatol Heintz.
Stensioella heintzi has an elongated body, a whip-like tail, and long, wing-like pectoral fins. In life, the animal would have looked vaguely like an elongatedratfish. Like thesympatricGemuendina,S. heintzi had armor made up of a complex mosaic of small, scale-liketubercles.
Stensioella is tentatively placed within Placodermi as being among the most basal of all placoderms, as from what can be discerned from the only whole specimen found, the shoulder joints of its armor appear to be very similar to other placoderms. Despite this detail, coupled with superficial similarities in skull plates, and gross, superficial similarities between its tubercles, and the tubercles of therhenanids, some paleontologists believe that there are very few concrete reasons forS. heintzi's placement in Placodermi. The paleontologist,Philippe Janvier[1] suggests that it was actually aholocephalid, and not a placoderm at all. However, if this is true, then the holocephalids (chimaeras,iniopterygians,petalodonts, et al.) diverged from sharks before theChondrichthyanDevonian radiation.
Aside from a superficially similarbodyplan to primitive holocephalids likeMenaspis, critics to Janvier's idea say that there is very little else in commonS. heintzi has with holocephalids.
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| Forerunners | 
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| Jawless fish |
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| Jawed fish |
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| Related | |||||||||||||
† extinct | |||||||||||||
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