Oksoko avarsan

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Oksoko
Temporal range:
Ma
↓
Holotype block assemblage (top) and line drawing (bottom)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Oviraptoridae
Subfamily: †
Heyuanninae
Genus: †Oksoko
Funston et al., 2020
Type species
†Oksoko avarsan
Funston et al., 2020

Oksoko (Oak-soak-oh; from

oviraptorid dinosaur from the Late Cretaceous of Asia, that lived in what is now the Nemegt Formation in Mongolia. It includes the type species
Oksoko avarsan.

History of discovery

Holotype block assemblage prior to fossil preparation

The first specimen of Oksoko, MPC-D 100/33, was discovered in 1974 by the Soviet-Mongolian Palaeontological Expedition at the Bügiin Tsav locality in the Nemegt Formation of Mongolia. It is represented by a partial subadult postcranial skeleton. The holotype specimen is a block of an assemblage of three individuals buried in life positions that has been labelled as MPC-D 102/110.

The first individual, subcatalogued as MPC-D 102/110a, is a partial skeleton of a juvenile preserving the

sediments and preservation state, which may suggest that MPC-D 102/11 is part of the holotype block assemblage.[1]

Another, isolated specimen was collected in 1998 at the Guriliin Tsav locality by a joint expedition from the Hayashibara Museum of Natural Sciences and the Mongolian Palaeontological Centre. It was catalogued as MPC-D 102/12 and represents postcranial skeleton of an adult individual.

Skull of holotype MPC-D 102/110a

This block was in 2006 confiscated from poachers by the General Intelligence Agency of Mongolia along with a fourth specimen, MPC-D 102/11, representing a partial juvenile skeleton preserving the skull. They were later returned to the Mongolian Palaeontological Center on December 14 during the same year, where they were posteriorly prepared by professionals. Though the exact localities of these specimens are currently unknown due to their theft, although the colour of their sediments and geochemical analyses confirm their provenance from the Nemegt Formation.

All of the specimens were later assigned to the new

Öksökö, one of the multiple triple-headed eagles in the Altaic mythologies, in reference to the holotypic block assemblage preserving three skulls. The specific name, O. avarsan, is taken from the Mongolian word аварсан (avarsan, meaning rescued) given that specimens of the genus were redeemed from fossil poachers.[1]

Although MPC-D 100/33 has been largely referred as a

metacarpal. To date, Oksoko is unequivocally known from at least two localities of the Nemegt Formation: Bügiin Tsav and Guriliin Tsav.[1]

Description

Size comparison with a human
Body size of three specimens

The

tyrannosaurids, the avialan Balaur bondoc, and caudipterid oviraptorosaurs.[1]

Classification

Forelimb bones of Oksoko, showing the two-fingered hand in (d)

The describers' phylogenetic analysis places it as a derived member of the subfamily

Heyuanninae in the family Oviraptoridae. It has been suggested that Oksoko represents a highly derived form in a series of oviraptorosaurs whose third digits have reduced over evolutionary time. Their cladogram is shown below (only relationships within Oviraptoridae are shown):[1]

Oviraptoridae

Paleoenvironment

Oksoko was found in the

titanosaurs are also known from the formation. Fossils of a pterosaur, crocodilians, and small mammals are also present.[3][4][5]

References

  1. ^
    PMID 33204472
    .
  2. PMID 27410683
    .
  3. doi:10.1016/j.palaeo.2017.10.031
    .
  4. doi:10.1016/j.palaeo.2017.10.023
    .
  5. S2CID 182937778
    .
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