Cherminotus

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Cherminotus
Temporal range: Late Cretaceous, 75  Ma
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Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Varanidae
Genus: Cherminotus
Borsuk-Bialynicka, 1984
Species:C. longifrons
Binomial name
Cherminotus longifrons
Borsuk-Bialynicka, 1984

Cherminotus is an extinct genus of monitor lizard from the Late Cretaceous of Mongolia. The type and only species, Cherminotus longifrons, was named in 1984.

A genus is a taxonomic rank used in the biological classification of living and fossil organisms, as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.

Monitor lizard genus of reptiles

The monitor lizards are large lizards in the genus Varanus. They are native to Africa, Asia and Oceania, but are now found also in the Americas as an invasive species. A total of 79 species are currently recognized.

The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series. The Cretaceous is named after the white limestone known as chalk which occurs widely in northern France and is seen in the white cliffs of south-eastern England, and which dates from this time.

Description and history

Cherminotus longifrons was first described in 1984 from the Barun Goyot Formation. More specimens were later found in the Djadokhta Formation in localities such as Ukhaa Tolgod. [1]

The Barun Goyot Formation is a geological formation dating to the Late Cretaceous Period. It is located within and is widely represented in the Gobi Desert Basin, in the Ömnögovi Province of Mongolia.

Cherminotus is small for a monitor lizard and has a longer snout than its closest relative, the living Earless monitor lizard. Cherminotus is also very similar in appearance to Aiolosaurus , another monitor from the Cretaceous of Mongolia. Both monitors have a single hole in the lacrimal bone called the lacrimal foramen. Other monitors and monitor ancestors have two holes in the lacrimal, making the presence of only one hole in Cherminotus a case of evolutionary reversal. [2]

Earless monitor lizard Earless monitor lizard

The earless monitor lizard is a semiaquatic, brown lizard native to the Southeast Asian island of Borneo. It is the only living species in the family Lanthanotidae and it is related to the true monitor lizards.

Aiolosaurus is an extinct genus of monitor lizard from the Late Cretaceous of Mongolia. The type and only species, Aiolosaurus oriens, was named in 2000 from Ukhaa Tolgod, a rich fossil site in the Campanian-age Djadochta Formation.

Lacrimal bone smallest and most fragile bone of the human skull and face

The lacrimal bone is a small and fragile bone of the facial skeleton; it is roughly the size of the little fingernail. It is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders. Several bony landmarks of the lacrimal bone function in the process of lacrimation or crying. Specifically, the lacrimal bone helps form the nasolacrimal canal necessary for tear translocation. A depression on the anterior inferior portion of the bone, the lacrimal fossa, houses the membranous lacrimal sac. Tears or lacrimal fluid, from the lacrimal glands, collect in this sac during excessive lacrimation. The fluid then flows through the nasolacrimal duct and into the nasopharynx. This drainage results in what is commonly referred to a runny nose during excessive crying or tear production. Injury or fracture of the lacrimal bone can result in posttraumatic obstruction of the lacrimal pathways.

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Priscagama is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia and China. It belongs to an extinct family of iguanians called Priscagamidae. Several incomplete skulls have been found in the Barun Goyot and Djadochta formations, and were originally referred to the genus Mimeosaurus; the type species Priscagama gobiensis was named in 1984 when it was recognized that these skulls belonged to a distinct species. Priscagama differs from most other priscagamids in having a more elongate, lightly-built skull. It is very similar in appearance to another priscagamid called Pleurodontagama, as the two can only be distinguished by the shape of their teeth.

Phrynosomimus is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia belonging to the extinct family Priscagamidae. The type species Phrynosomimus asper was named in 1996. Fossils have been found in the Barun Goyot and Djadochta formations and include several complete skulls. Phrynosomimus has a short, triangular skull with bony spikes projecting from the back, stemming from the squamosal and parietal bones. These spikes give it a similar appearance to the modern horned lizard Phrynosoma and inspire its name, which means "Phrynosoma mimic". Like other priscagamids it has an acrodont dentition, meaning that its teeth grow from the margins of the jaws rather than their inner surfaces, as is the case for the pleurodont dentitions of most lizards.

Ukhaatherium is a now extinct species of mammal that lived during the upper Cretaceous about 84 to 72 million years ago in today's East Asia. It is known above all from Ukhaa Tolgod, where it alone is occupied by eight individuals, six of them completely. In general, Ukhaatherium weighing about 32 g was quite small and resembled today's insect eaters. In addition, there were still some original skeletal features.

<i>Almas ukhaa</i> species of reptile (fossil)

Almas is a genus of troodontid theropod dinosaur from the Late Cretaceous of Mongolia. It contains a single species, Almas ukhaa, named in 2017 by Pei Rui and colleagues, based on a partial articulated skeleton. The only known specimen was found in the Djadochta Formation, which is late Campanian in age.

References

  1. Gao, K.; Norell, M.A. (2000). "Taxonomic composition and systematics of Late Cretaceous lizard assemblages from Ukhaa Tolgod and adjacent localities, Mongolian Gobi Desert". Bulletin of the American Museum of Natural History. 249: 1–118. doi:10.1206/0003-0090(2000)249<0001:tcasol>2.0.co;2.
  2. Conrad, J.L. (2008). "Phylogeny and systematics of Squamata (Reptilia) based on morphology". Bulletin of the American Museum of Natural History. 310: 1–182. doi:10.1206/310.1.