Avalonnectes
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Avalonnectes Temporal range: Early Jurassic, 199.6–198 Ma |
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| Holotype of Avalonnectes arturi | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | †Sauropterygia |
| Order: | †Plesiosauria |
| Family: | †Rhomaleosauridae |
| Genus: |
†Avalonnectes Benson, Evans & Druckenmiller, 2012 |
| Type species | |
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†Avalonnectes arturi Benson, Evans & Druckenmiller, 2012 |
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Avalonnectes is an extinct genus of small-bodied rhomaleosaurid known from the Early Jurassic period (most likely earliest Hettangian stage) of the United Kingdom. It contains a single species, A. arturi.
Avalonnectes is known from the holotype specimen NHMUK 14550, which consists of the posterior portion of a skull, and a nearly complete, three-dimensionally preserved and articulated postcranial skeleton. Another partial postcranial skeleton which was referred to it is AGT uncatalogued. Both specimens were collected at Street, of Somerset, from the Pre-Planorbis beds of the Blue Lias Formation of the Lower Lias Group. These beds likely occur below the first occurrence of the ammonite Psiloceras planorbis. Thus, they probably fall within the earliest Hettangian P. tilmanni Chronozone, which is about 199.6-198 million years old, immediately following the Triassic–Jurassic Boundary. Plesiosaurs fossils which were discovered at Street represent the earliest known occurrence of the Plesiosauria. Hence, Avalonnectes is one of the oldest plesiosaurs to date.
Avalonnectes is a small-bodied rhomaleosaurid with 18–19 dorsal vertebrae. This low number represents its autapomorphy. A phylogenetic analysis performed by Benson et al. (2012) found it to be a basal rhomaleosaurid. The cladogram below shows Avalonnectes phylogenetic position among other plesiosaurs following Benson et al. (2012).
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