''Sulcatidens'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

agamid Agamidae is a family of over 300 species of iguanian lizards indigenous to Africa, Asia, Australia, and a few in Southern Europe. Many species are commonly called dragons or dragon lizards. Overview Phylogenetically, they may be sister to th ...

lizard from the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was p ...

of Australia. Fossils are known exclusively from the

Riversleigh World Heritage Area Riversleigh World Heritage Area is Australia's most famous fossil location, recognised for the series of well preserved fossils deposited from the Late Oligocene to more recent geological periods. The fossiliferous limestone system is located ne ...

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

. It contains only one species, ''S. quadratus''.

Discovery and naming

The

holotype specimen A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

, QM F18010, of ''Sulcatidens'' was discovered from the 'Wayne's Wok' site at the

, in the

Boodjamulla National Park Boodjamulla National Park, formerly known as Lawn Hill National Park, is a national park in the Shire of Burke, Queensland, Australia. The Riversleigh World Heritage Area is a World Heritage Site within the park. The park lies on the traditiona ...

of north-western

. It consists of a partial

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The ...

retaining teeth. In addition, an incomplete maxilla was also referred to the species. It was described alongside other agamid material from Riversleigh by Covacevich ''et al.'' in 1990. The generic name is derived from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...

word ''sulcare'' ("to furrow"), in reference to the notches in the middle of the posterior maxillary teeth. The specific name comes from the Latin ''quadratus'' ("to make square"), which refers to the square-like shape of the posterior maxillary teeth.

Description

The teeth of ''Sulcatidens'', and all other agamids, are described as

acrodont Acrodonty (from Greek ''akros'' 'highest' + ''dont'' 'tooth') is an anatomical placement of the teeth at the summit of the alveolar ridge of the jaw, without sockets, characteristic of bony fish. Functionally, acrodont tooth implantation may be rela ...

, as they are attached to the apex of the jaw bone. The four posterior most maxillary teeth are roughly square in appearance and situated close to one another. When viewed occlusally, the teeth have a flattened labial surface. It differs from all other agamids in that the posterior most maxillary teeth have distal edges that are notched into the mesial edge of the preceding tooth.

Paleobiology

''Sulcatidens'' is known exclusively from the 'Wayne's Wok' site at Riversleigh, which dates to the

. At the time, Riversleigh was covered in a permanently wet and closed canopy rainforest environment.

References

Agamidae Agamid lizards of Australia Prehistoric lizard genera Fossil taxa described in 1990 {{Paleo-lizard-stub