Dactylosaurus comes from the Greekdaktulos (δακτυλος), "finger" and sauros (σαυρος), meaning "lizard" or "reptile."
Description
Dactylosaurus was a small reptile measuring up to 50 cm (1.6 ft) long.[2] The nasal bones of Dactylosaurus meet and are broadly structured.[3] The upper temporal fenestra is large and kidney-shaped.[3] There are 17 cervicalvertebrae[3] and the cervical ribs have anterior processes.[3] The maxillae of Dactylosaurus extended broadly up the side of the snout.[1]
D. gracilis
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.[3] 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.[4] The original holotype of D. gracilis is considered a juvenile,[3] 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]
Distribution
Muschelkalk, a German form of shelly limestone, occasionally produces Dactylosaurus fossils in its lowest layers.
In terms of geology, 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 lowermost Muschelkalk (Middle Triassic), inter alia in the Gogolin 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 of Dactylosaurus was found in Gogolin. Presently, this in the only site where Dactylosaurus remains are accessible to collect.[7][8][9]
^ abcdefghRieppel, O & L Kebang (1995), "Pachypleurosaurs (Reptilia, Sauropterygia) from the Lower Muschelkalk, and a review of the Pachypleurosauroidea." Fieldiana Geol. N.S. 32: 1-44.
^Sues H-D., Carroll R.L. 1985. The pachypleurosaurid Dactylosaurus schroederi (Diapsida: Sauropterygia). Canadian Journal of Earth Sciences 22(11): 1602-1608
^Kowal-Linka M., Bodzioch A. 2012a. Warstwy kościonośne z Dactylosaurus (Reptilia, Sauropterygia)
z retu (trias dolny, olenek) Opolszczyzny Bonebeds with Dactylosaurus (Reptilia, Sauropterygia) from the Röt (Lower Triassic, Olenekian) in the Opole Silesia region (S Poland). Przegląd Geologiczny 60 (12): 646–649
^Kowal-Linka M., Bodzioch A. 2012b. New findings of vertebrate remains from the Röt (Lower Triassic, Olenekian) in the vicinity of Gogolin (Opole Silesia, S Poland). [W:] Krasiejów - inspiracje paleontologiczne / Krasiejów - paleontological inspirations. E. Jagt-Yazykova, J. Jagt, A. Bodzioch, D. Konietzko-Meier (red.). Zakład Poligraficzno-Wydawniczy "Plik", Bytom: 70-80. ISBN978-83-916841-8-4
^Kowal-Linka M., Bodzioch A. 2017. Genesis of the Lower Triassic bonebeds from Gogolin (S Poland): The impact of microbial mats on trapping of vertebrate remains. Palaeogeography, Palaeoclimatology, Palaeoecology 466, 38–58
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