| Dactylosaurus | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | †Sauropterygia |
| Family: | †Pachypleurosauridae |
| Genus: | †Dactylosaurus Gürich,1884 |
| Type species | |
| †Dactylosaurus gracilis Gürich, 1884 | |
| Synonyms | |
| |
Dactylosaurus is agenus ofnothosaur in thefamilyPachypleurosauridae. Along withAnarosaurus,Dactylosaurus was one of the earliest known pachypleurosaurs to come fromEurope.[1]
Dactylosaurus comes from theGreekdaktulos (δακτυλος), "finger" andsauros (σαυρος), meaning "lizard" or "reptile."
Dactylosaurus was a small reptile measuring up to 50 cm (1.6 ft) long.[2] The nasal bones ofDactylosaurus meet and are broadly structured.[3] Theupper temporal fenestra is large andkidney-shaped.[3] There are 17cervicalvertebrae[3] and the cervicalribs have anterior processes.[3] Themaxillae ofDactylosaurus extended broadly up the side of the snout.[1]
Theholotype specimen (MGUWR WR 3871s) ofD. gracilis was only a partialskeleton, consisting of theanterior end alone.[1] Because it differed slightly from the fossils ofD. gracilis, it was first thought to belong to the speciesD. schroederi,[1] which is now considered ajunior synonym for juvenileD. gracilis.[3] Once this was established, the juvenile fossil, which was found before the adult fossils, became the holotype. The onelimb that was found (a left forelimb), was noted to have a slimmerradius andulna thanNeusticosaurus,[1] a similar nothosaur fromEurope.[1]D. gracilis is the smallest known species in its family,[1] which includes the much more recognizedKeichousaurus, a nothosaur often remembered for its small size.[4] The original holotype ofD. gracilis is considered a juvenile,[3] however the size of a nothosaur when itsbones harden is used to show size, making the estimate as smallest member of its family still valid.[1]
Dactylosaurus lived in the Early and MiddleTriassic period during the LateOlenekian andAnisian[3]faunal stage, of central Europe.[5]
In terms ofgeology, they are found:1) in the uppermost Röt (uppermost Buntsandstein; Lower Triassic): e.g. Michałkowice (Siemianowice Śląskie) and Kamień Śląski, S Poland,[3] (the second location is not sure because Röt is not exposed there),2) in the lowermostMuschelkalk (Middle Triassic), inter alia in theGogolin Formation - Gogolin and its vicinity, S Poland.[5][6]
In 2012, the new Röt site (~ 247 Ma; Lower Triassic; the latest Olenekian) with abundant disarticulated remains ofDactylosaurus was found in Gogolin. Presently, this in the only site whereDactylosaurus remains are accessible to collect.[7][8][9]
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