Allkaruen

Source: Wikipedia, the free encyclopedia.

Allkaruen
Temporal range:
Middle
Ma
↓
[1]
Skeletal elements
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Order: †Pterosauria
Clade: †
Macronychoptera
Clade: †Novialoidea
Clade: †
Breviquartossa
Clade: †
Pterodactylomorpha
Genus: †Allkaruen
Codorniú et al. 2016[2]
Species:
†A. koi
Binomial name
†Allkaruen koi
Codorniú et al. 2016[2]

Allkaruen (meaning "ancient brain") is a

Cañadon Asfalto Formation in Argentina.[2]
It contains a single species, Allkaruen koi.

Description

Endocast of the brain

As demonstrated by a

flocculus and cerebral hemispheres, and the ratio between the length of the brain and the height of the hindbrain.[2] In addition, the relative orientations of the frontal bone and lateral semicircular canal are more similar to Rhamphorhynchus than Anhanguera, while the optic lobes are positioned lower than the forebrain as in pterodactyloids.[2][3] This unique combination of characters indicates that the anatomy of the braincase in pterodactyloids evolved through mosaic evolution
.

The parietals of Allkaruen were long, being 60% of the length of the frontals; the frontals themselves were broad, flat, and extensively pneumatized. The lower jaw was about 3.5 times the length of the section of the skull that is preserved, and it is curved upwards at its tip. The dentary bore four or five tooth sockets in its front half, and in the latter half they were replaced by a groove; this combination is unique among pterosaurs.[2]

Allkaruen was a small pterosaur. The holotype specimen would have been an adult, since its skull was entirely fused.[2]

Discovery and naming

The holotype of Allkauren consists of a braincase (MPEF-PV 3613), a mandible (MPEF-PV 3609), and a cervical vertebra (MPEF-PV 3615); a similar cervical vertebra (MPEF-PV 3616) was also referred to the genus.[2] These elements were in 2000 discovered in the Cañadón Asfalto Formation, Cerro Cóndor, Chubut, Argentina, which has been dated to the Middle-Late Toarcian, 179.17 ± 0.12-178.07 ± 0.21 m.a (although earlier estimates have suggested an earliest-Bathonian age).[4][5] Other elements, mostly disarticulated and consisting of a number of limb bones as well as another mandible, were also discovered at the site.[2][6]

The name Allkaruen is Tehuelche in origin, being derived from all ("brain") and karuen ("ancient"). The specific name, koi, originates from the Tehuelche word for "lake", in reference to the fact that the type locality would have been a saline lake.[2][7]

Classification

In 2016, two

phylogenetic analyses were conducted based on the dataset from the description of Darwinopterus in order to determine the phylogenetic position of Allkaruen.[8] One analysis was restricted to the holotype braincase, while the other included the holotype mandible and cervical vertebrae as well. Allkaruen was consistently recovered as the sister taxon of the Monofenestrata; the consensus of the 360 most parsimonious trees is shown below.[2]

 Breviquartossa 

In their 2024 description of

Cuspicephalus scarfi than to Quetzalcoatlus. Their results are shown in the cladogram below:[9]

Monofenestrata

References

  1. S2CID 225120452
    . Retrieved 27 August 2021.
  2. ^
    PMID 27635315
    .
  3. ^
    S2CID 4431861
    .
  4. doi:10.1007/978-3-030-95959-3_4
    . Retrieved 2 May 2022.
  5. hdl:11336/78351
    .
  6. ^ Codorniú, L.; Rauhut, O.W.M.; Pol, D. (2010). "Osteological features of Middle Jurassic pterosaurs from Patagonia (Argentina)". Acta Geoscientica Sinica. 31 (suppl. 1): 12–13.
  7. S2CID 129090656
    .
  8. PMID 19828548
    .
  9. ISSN 0272-4634
    .
Retrieved from "https://en.wikipedia.org/w/index.php?title=Allkaruen&oldid=1214307989"