''Retinosaurus'' (meaning "amber lizard") is an extinct genus of scincomorph lizard from the Early Cretaceous of

Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...

. The genus contains a single species, ''Retinosaurus hkamtiensis'', known from a specimen preserved in

amber Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In ...

Discovery and naming

The

holotype 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 sever ...

specimen, GRS 29689, was legally obtained from a Myanmar gem dealer in 2019. It was subsequently announced in a preprint in October 2021, and validly described as a new genus and species of lizard by Čerňanský ''et al.'' in January 2022. The fossil was discovered in the

Hkamti amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. The ...

site of Myanmar, which dates to the early

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0 ...

, approximately 110 million years ago. The holotype, which represents a juvenile individual, includes a well-preserved

articulated An articulated vehicle is a vehicle which has a permanent or semi-permanent pivot joint in its construction, allowing it to turn more sharply. There are many kinds, from heavy equipment to buses, trams and trains. Steam locomotives were sometim ...

skull, partial

postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...

, and skin impressions. In addition to the lizard fossil material, the amber also contains several

coleopterans Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 described ...

. The generic name, "''Retinosaurus''", is derived from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

words "retine", referring to liquid

resins In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on natu ...

created by trees, and "saurus", meaning "lizard". The specific name, "''hkamtiensis''", references Hkamti, the type locality.

Classification

In all but one of the phylogenetic analyses performed by the describing authors, ''Retinosaurus'' was recovered as a Pan- xantusiid. Most phylogenies resulted with ''Retinosaurus'' as a

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to a clade formed by '' Tepexisaurus'' + Xantusiidae. Because the holotype represents an immature individual, the authors explain that any phylogenetic results should be treated with caution.

References

{{taxonbar, from = Q110921227 Scincomorpha Fossil taxa described in 2022 Cretaceous lizards Early Cretaceous reptiles of Asia Fossils of Myanmar