Cryptovenator
| Cryptovenator | ||||||||||||
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Holotype of Cryptovenator hirschbergeri , an anterior half of the lower jaw (lower left for comparison a skull of Dimetrodon grandis , not to scale) |
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| Temporal occurrence | ||||||||||||
| Upper upper carbon | ||||||||||||
| 300 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Cryptovenator | ||||||||||||
| Fröbisch et al., 2011 | ||||||||||||
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Cryptovenator ( Greek kryptos "hidden", "secret" and Latin venator "hunter") describes a genus of basal sphenacodontid " pelycosaurs " ( Synapsida ) from the late Upper Carboniferous Germany. The type - and only species - Cryptovenator hirschbergeri was first described in 2011 using the front part of a lower jaw , which was a sandstone layer of the middle Remigiusberg formation of the Saar-Nahe basin ( Rhineland-Palatinate) comes from. With an age of around 300 million years, this fossil represents the oldest remains of an amniote in Germany . The species was named after the then district administrator of the Kusel district , Winfried Hirschberger , who had made a name for himself in the museum's appreciation of the region's paleontological finds.
With an estimated total length of around one meter, Cryptovenator is one of the smaller representatives of the Sphenacodontids.
Location
The type and only known specimen of Cryptovenator hirschbergeri comes from the western edge of the Remigiusberg quarry near Haschbach in southern Rhineland-Palatinate. The quarry is the type locality of the Remigiusberg Formation, dated 300 million years ago (late Gzhelian ), the basal formation of the Rotliegend of the Saar-Nahe basin. The find layer belongs to a mixed carbonate - siliciclastic sequence of deposits of the so-called Theisbergstegen lake (Lower Theisbergstegen bank).
The Remigiusberg quarry has produced many well-preserved fossils of fish and amphibians and is also rich in fossil footsteps from purely terrestrial land vertebrates . These traces were believed to have been created by diadectids , parareptiles , diapsids and synapsids . Body fossils of amniotes were not known from there until the discovery of Cryptovenator .
description
The holotype of Cryptovenator hirschbergeri is the front half of a lower jaw, which consists mainly of the dental and the length of which is about 5 centimeters. It is equipped with 11 teeth, the front three of which are significantly larger than the other teeth - so-called caniniform ( fang-like ) teeth (see also → heterodontics ). Of these three canine-shaped teeth, the second is the largest. All teeth have an approximately teardrop-shaped outline. What is striking is the great height of the entire anterior part of the dental, including the symphysis region . In addition, the lower, posterior part of the dental is clearly curved upwards. All of these are typical features of Sphenacodontids, which are found in a similar way in the genera Sphenacodon and Dimetrodon .
| Cladogram according to Fröbisch et al. (2011) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| The genus Cryptovenator is a basic, but not the most basic, representative of the Sphenacodontidae. |
Systematics
The teardrop-shaped contour of the teeth, the canine-shaped anterior teeth, the high symphysis and the pronounced upward curvature of the posterior part of the traditional jawbone undoubtedly identify Cryptovenator as sphenacodontids. The compact formation of the jaw and the only moderately pronounced heterodontics, on the other hand, are considered autapomorphies of Cryptovenator . In the case of the geologically younger representatives of the Sphenacodontids, such as Sphenacodon , Ctenospondylus or Dimetrodon from the early Permian, the heterodontics are much more pronounced - u. a. In these forms, the first tooth of the lower jaw is significantly reduced in size. Therefore, Cryptovenator is a relatively primitive sphenacodontid. But because it shares more features with the most strongly derived genera Dimetrodon or Sphenacodon than with Secodontosaurus , Cryptovenator is not quite at the base of the Sphenacodontidae.
meaning
The traditional permocarbone fauna of the Saar-Nahe Basin in general and that of the Remigiusberg Formation in particular is dominated by aquatic vertebrates. In contrast, in the fossil record of other Rotliegend basins, for example in the Thuringian Forest ( Bromacker ) or Upper Silesia ( Nowa Ruda ), basal synapsids ("pelycosaurs") occur relatively frequently.
Cryptovenator is the first find of an amniote in the Saar-Nahe basin and especially the first find of a representative of sphenacodontid "pelycosaurs", which until then were only indirectly represented by the Ichnotaxon Dimetropus . After Macromerion schwarzenbergii from Kounová in the Czech Republic , Cryptovenator is also the second oldest sphenacodontid find in Europe .
The direct evidence of sphenacodontids, the most strongly derived forms of the “pelycosaurs”, in the late Carboniferous supports the assumption that the diversification of the early amniotes took place long before the transition from the Carboniferous to the Permian. However, due to the sparse Carboniferous fossil record of the amniotes, it remains unclear whether this process occurred relatively quickly within a few million years at the end of the Carboniferous or dates back well into the Early Carboniferous.
literature
- Jörg Fröbisch, Rainer R. Schoch, Johannes Müller, Thomas Schindler, Dieter Schweiss: A new basal sphenacodontid synapsid from the Late Carboniferous of the Saar-Nahe Basin, Germany. Acta Palaeontologica Polonica. Vol. 56, No. 1, 2011, pp. 113-120, doi : 10.4202 / app.2010.0039 .
- Dieter Schweiss: Cryptovenator hirschbergeri - a chance find of extraordinary importance . Westrichkalender 2012, pp. 140–144.
- Sebastian Voigt, Jan Fischer, Thomas Schindler, Michael Wuttke, Frederik Spindler, Larry F. Rinehart: On a potential fossil hotspot for Pennsylvanian - Permian non-aquatic vertebrates in Central Europe. Paleontology, stratigraphy, facies (Freiberg research books, series C). Vol. 22 (548), 2014, pp. 39-44 ( ResearchGate ).