Telmasaurus

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Telmasaurus
Temporal range:
Ma
↓
Life restoration
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Superfamily: Varanoidea
Genus: †Telmasaurus
Gilmore, 1943
Species:
†T. grangeri
Binomial name
†Telmasaurus grangeri
Gilmore, 1943

Telmasaurus is an extinct genus of

Djadokha and Barun Goyot Formations that date between the early and middle Campanian stage from approximately 80 to 75 million years ago. The type species
Telmasaurus grangeri was named in 1943.

Description

Telmasaurus grangeri was named in 1943 and is now known from several fossils.[1] Only two skulls are known, and the snout region is missing from both. Based on the size of these skulls, Telmasaurus was larger than other Cretaceous varanoid lizards, approaching the size of modern monitor lizards. Its skull is flatter than most other varanoids. The fusion of two bones in the skull called frontals links Telmasaurus with other early varanids like Paravaranus. The lacrimal bone of Telmasaurus has a single hole in it, as do those of other early varanoids. The vertebrae of Telmasaurus are also known, and the way they attach to each other is very different from the way those of modern monitor lizards do.[2] A small crest running between the eye sockets is a distinguishing feature of the genus.[3]

Classification

Telmasaurus was first classified in the family

helodermatids
and the group containing monitor lizards and snakes. Below is a cladogram from the 1998 anaylis:

Varanoidea 

Helodermatidae

†Gobidermatidae

†Estesia

†Telmasaurus

 Thecoglossa 
 Pythonomorpha 

†Mosasauroidea

Serpentes

 
Lanthanotidae
 

†Cherminotus

Lanthanotus

 Varanidae 

†Saniwa

†Saniwides

Varanus

In a 2008 analysis, the basal positioning of Telmasaurus remained well supported, but it was grouped with another varanoid called Saniwides. Saniwides was once classified in Varanidae as a close relative of living monitor lizards. Other Cretaceous varanids like Cherminotus and Aiolosaurus are similar in appearance to Telmasaurus, but Telmasaurus is a more primitive member of Varanoidea. Below is a cladogram from the 2008 analysis:[4]

Varanoidea 

†Mosasauria

†"Saniwa" feisti

†

Necrosaurus cayluxi

†Saniwides mongoliensis

†Telmasaurus grangeri

 Varanidae (monitor lizards)

†Aiolosaurus oriens

 
Lanthanotinae
 

†Cherminotus longifrons

Lanthanotus borneensis

 
Varaninae
 

†

Ovoo gurvel

†Saniwa ensidens

Varanus

References

  1. ^ a b Borsuk-Bialynicka, M. (1984). "Anguimorphans and related lizards from the Late Cretaceous of the Gobi Desert, Mongolia" (PDF). Palaeontologica Polonica. 46: 5–105.
  2. ^ Molnar, R.E. (2004). "The long and honorable history of monitors and their kin". In Pianka, E.R.; King, D.; King, R.A. (eds.). Varanoid Lizards of the World. Bloomington: Indiana University Press. pp. 10–67.
  3. PMC 1691912
    .
  4. S2CID 83550662
    .
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