Adriosaurus

Adriosaurus
Temporal range: Late Cretaceous, 95 Ma
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London specimen of A. suessi above, with interpretative drawing of its skull on the left. Vienna holotype specimen of A. suessi below.
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Clade: Pythonomorpha
Genus: Adriosaurus
Seeley, 1881
Species
  • A. microbrachis Palci & Caldwell, 2007[1]
  • A. skrbinensis Caldwell & Palci, 2010[2]
  • A. suessi Seeley, 1881 (type)

Adriosaurus is an extinct genus of squamate which lived in what is now Slovenia and other parts of Europe during the Late Cretaceous. It was a small, snake-like reptile, with the type species Adriosaurus suessi measuring up to 30 cm (12 in) in length. Adriosaurus represents the first occurrence of vestigial limbs in fossil lizards, having lost its manus and forearm completely in order to elongate its axial skeleton.[3][4][5] These unique anatomical features led to discussions of the evolutionary patterns of limb reduction in Squamata.[5]

Adriosaurus includes three species: A. microbrachis (“micro”, meaning small, and “brachis”, meaning arm, referring to the vestigial forelimb composed of only the humerus),[5] A. skrbinensis (named after the location where they found the fossil, Skrbina, northwest of Komen, Slovenia) and A. suessi. A. microbrachis lacks many crucial characters to be qualified for cladistic analysis.[6]

  1. ^ Alessandro Palci & Michael W. Caldwell (2007). "Vestigial forelimbs and axial elongation in a 95-million-year-old non-snake squamate". Journal of Vertebrate Paleontology. 27 (1): 1–7. doi:10.1671/0272-4634(2007)27[1:VFAAEI]2.0.CO;2.
  2. ^ Michael W. Caldwell & Alessandro Palci (2010b). "A new species of marine ophidiomorph lizard, Adriosaurus skrbinensis, from the Upper Cretaceous of Slovenia". Journal of Vertebrate Paleontology. 30 (3): 747–755. doi:10.1080/02724631003762963.
  3. ^ Ancient lizard missing front limbs - LiveScience - nbcnews.com
  4. ^ "Aquatic Lizard Was Losing Its Front Limbs". Archived from the original on 2012-10-16. Retrieved 2019-05-07.
  5. ^ a b c Alessandro Palci and Michael W. Caldwell. 2007. Vestigial Forelimbs and Axial Elongation in a 95 Million-Year-Old Non-Snake Squamate. Journal of Vertebrate Paleontology Vol. 27, No. 1. pp. 1-7
  6. ^ MICHAEL W. CALDWELL and ALESSANDRO PALCI. 2010, A NEW SPECIES OF MARINE OPHIDIOMORPH LIZARD, ADRIOSAURUS SKRBINENSIS , FROM THE UPPER CRETACEOUS OF SLOVENIA. Journal of Vertebrate Paleontology Vol. 30, No. 3. pp. 747-755