| Dactylosaurus Temporal range: Middle Triassic (Anisian?) |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Sauropsida |
| Superorder: | Sauropterygia |
| Order: | Nothosauroidea |
| Suborder: | Pachypleurosauria |
| Family: | Pachypleurosauridae |
| Genus: | Dactylosaurus Gürich, 1884 |
| Species | |
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| Synonyms | |
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Dactylosaurus is a genus of nothosaur in the family Pachypleurosauridae. Along with Anarosaurus, Dactylosaurus was one of the earliest known pachypleurosaurs to come from Europe.[1]
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Dactylosaurus comes from the Greek daktulos (δακτυλος), "finger" and sauros (σαυρος), meaning "lizard" or "reptile."
The nasal bones of Dactylosaurus meet and are broadly structured.[2] The upper temporal fenestra is large and kidney-shaped.[2] There are 17 cervical vertebrae[2] and the cervical ribs have anterior processes.[2] The maxillae of Dactylosaurus extended broadly up the side of the snout.[1]
The holotype specimen (MGUWR WR 3871s) of D. gracilis was only a partial skeleton, consisting of the anterior end alone.[1] Because it differed slightly from the fossils of D. gracilis, it was first thought to belong to the species D. schroederi,[1] which is now considered a junior synonym for juvenile D. gracilis.[2] Once this was established, the juvenile fossil, which was found before the adult fossils, became the holotype. The one limb that was found (a left forelimb), was noted to have a slimmer radius and ulna than Neusticosaurus,[1] a similar nothosaur from Europe.[1] D. gracilis is the smallest known species in its family,[1] which includes the much more recognized Keichousaurus, a nothosaur often remembered for its small size.[3] The original holotype of D. gracilis is considered a juvenile,[2] however the size of a nothosaur when its bones harden is used to show size, making the estimate as smallest member of its family still valid.[1]
Dactylosaurus lived in the Middle Triassic period during the Anisian faunal stage, of central Europe.[4] In terms of geology, they are found in the lowest Muschelkalk layers, in and around the Gogolin Formation.[4]
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