Adriosaurus

Adriosaurus
Temporal range: Late Cretaceous, 95Ma
↓
London specimen of A. suessi above, with interpretative drawing of its skull on the left. Vienna holotype specimen of A. suessi below.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Infraorder: Anguimorpha
(unranked): 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 aquatic lizard that lived about 95 million years ago. It was snake-like and grew 10 to 12 inches. This is the first fossil record of vestigial limbs in lizards, and gives scientists a glimpse back to the time when terrestrial lizards evolved to be limbless and returned to their watery origins.[3][4]

Cladogram based on Palci and Caldwell (2010a), Caldwell and Palci (2010b)[5][2]: 

Anguimorpha

Anguidae


Xenosaurus

Shinisaurus

Heloderma


Lanthanotus

Varanus



Pythonomorpha


Aigialosauridae

Mosasauridae



Ophidiomorpha
Dolichosauridae

Coniasaurus

Dolichosaurus


Pontosaurus lesinensis

Pontosaurus kornhuberi

Aphanizocnemus


Adriosaurus skrbinensis

Adriosaurus suessi

Acteosaurus

Ophidia












References

  1. ↑ 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 27 (1): 1–7. doi:10.1671/0272-4634(2007)27[1:VFAAEI]2.0.CO;2.
  2. ↑ 2.0 2.1 Michael W. Caldwell and 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 - MSNBC.com
  4. ↑ Aquatic Lizard Was Losing Its Front Limbs
  5. ↑ Alessandro Palci and Michael W. Caldwell (2010a). "Redescription of Acteosaurus tommasinii von Meyer, 1860, and a discussion of evolutionary trends within the clade Ophidiomorpha". Journal of Vertebrate Paleontology 30 (1): 94–108. doi:10.1080/02724630903409139.