Cryptolacerta
| Cryptolacerta | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Eocene ( Lutetium ) | ||||||||||||
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| Scientific name | ||||||||||||
| Cryptolacerta | ||||||||||||
| Müller et al., 2011 | ||||||||||||
Cryptolacerta is a small, extinct lizard from the Eocene , the discovery of which gave important clues to the systematics of scale reptiles. The holotype of Cryptolacerta hassiaca , the only known species, was found in the Messel mine in Hesse and is kept in the Senckenberg Nature Museum . The chosen generic name refers to the burrowing, hidden way of life of the animals ( Gr .: "Crypto" = hidden, Latin : "Lacerta" = lizard), the specific epithet hassiaca refers to the place of discovery in Hesse.
The exact investigation, including using computer tomography at the Helmholtz Center Berlin for Materials and Energy , provided the basis for an exact morphological description of the fossil .
features
Cryptolacerta had a head-trunk length of seven centimeters, plus the tail, which is largely missing in the only previously known fossil. Their anatomical characteristics are a mosaic of lizard features and double creeping features . Cryptolacerta has a capsule-like, heavily ossified skull in common with the double creeps . The muzzle is blunt and rounded. The jaws have heterodontic dentition with 14 teeth on the dental , 7 on the premaxillary and 12 on the maxillary . The outer nostrils are small. Overall, the skull of Cryptolacerta shows how the skull of the double sneak - which has the function of a drill head and enables the animals to dig - developed from a lizard-like skull.
The fore and hind feet of Cryptolacerta are greatly reduced compared to the rest of the bones of the fore and hind legs. The phalangeal formula is 2-3-4-4 / 5? -3 and shows that no toe has been reduced.
Systematics
Cryptolacerta is most closely related to the real lizards (Lacertidae) and the double snakes (Amphisbaenia), but closer to the latter, which can be proven by 19 common characteristics. This refutes the thesis that snakes (Serpentes) and double creeps arose from a common burrowing ancestor. The common taxon of Lacertidae and Amphisbaenia is called Lacertibaenia and was established by Vidal and Hedges as early as 2005 after molecular biological investigations had indicated a relationship between the two groups. The separation of the trunk groups of lizards and double snakes - determined using the molecular clock method - took place in the late Cretaceous 20 million years before the appearance of Cryptolacerta . Due to the island geography of the European continent in the palaeogene , Europe became a refuge for archaic Mesozoic scaled reptiles at this time .
The following diagram shows the position of Cryptolacerta as a sister group of the double sneaks in a common clade with the lizards.
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swell
- Johannes Müller, Christy A. Hipsley, Jason J. Head, Nikolay Kardjilov, André Hilger, Michael Wuttke & Robert R. Reisz (2011): Eocene lizard from Germany reveals amphisbaenian origins. Nature , Volume 473, pages 364-367, doi : 10.1038 / nature09919
- ↑ Nicolas Vidal, S. Blair Hedges: The phylogeny of squamate reptiles (lizards, snakes, and amphisbaenians) inferred from nine nuclear protein-coding genes. (PDF; 164 kB) In: Comptes Rendus Biologies. 328, No. 10-11, 2005, pp. 1000-1008, doi : 10.1016 / j.crvi.2005.10.001