Ubirajara jubatus

From Wikipedia, the free encyclopedia

Ubirajara
Temporal range: Late Aptian, 115–113 Ma
PreꞒ
Ꞓ
O
S
D
C
P
T
J
K
Pg
N
↓
Ubirajara jubatus revised.png
A reconstruction of "Ubirajara jubatus" with erect quills and a relaxed mane.
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Compsognathidae
Genus: †Ubirajara
Smyth et al., 2020[1]
Species:
†U. jubatus
Binomial name
†Ubirajara jubatus
Smyth et al., 2020[1]

Ubirajara ("lord of the spear"; the "J" is pronounced the same as in English) is a genus of compsognathid theropod that lived during the early Cretaceous period in what is now Brazil. It is known by a single species, Ubirajara jubatus, recovered from the Crato Formation. It has been described as the first dinosaur discovered with preserved integumentary structures.[2] Such proto-feathers, most likely used for display, include slender monofilaments associated with the base of the neck, increasing in length along the dorsal thoracic region, where they would form a mane, as well as a pair of elongate, ribbon-like structures likely emerging from its shoulders.[2][3]

Discovery and naming[]

Workers recovered a number of fossils from a chalk quarry located between Nova Olinda and Santana do Cariri. In 1995, these were acquired by the Staatliches Museum für Naturkunde Stuttgart and moved to Germany after an export permit was allegedly obtained.[1][4]

These fossils have been alleged to have been illegally imported into Germany out of Brazil in 1995, as Brazilian laws do not allow the removal of fossils from its territory, nor for studies on them to be conducted without the participation of at least one Brazilian scientist.[5][6][7] As a result, Brazilian scientists are campaigning for the repatriation of the fossils.[8]

One of the pieces was a chalk plate that had already been split by the workers. Further preparation by a sharp steel pin and X-ray photography revealed the presence of a small theropod skeleton.[1][failed verification][2]

The genus was erected by Robert S. H. Smyth, David Michael Martill, Eberhard Frey, Hector Eduardo Rivera-Silva and Norbert Lenz in December 2020.[1] The generic name means "Lord of the Spear" in the local Tupi language in reference to the shoulder spikes. The specific name means "maned" in Latin, referring to the mane on its back.[2][9]

Due to the ethical issues involving the potentially illegal transfer of the fossil from Brazil to Germany, the article was "temporarily removed" only a few days after being published.[10]

The holotype, SMNK PAL 29241, was discovered in a layer of the Crato Formation, dating from the Aptian, about 115 million years old. It consists of a partial skeleton lacking the skull, preserved on a slab and counterslab. It contains nine neck vertebrae, thirteen back vertebrae, two sacral vertebrae, the shoulder girdle, one neck rib, seven dorsal ribs, fifteen belly ribs and the almost complete left arm. Apart from the bones, the fossil preserves remains of the plumage, skin, granulate structures in the torso and the keratin sheaths of the hand claws. The skeleton is partially articulated. It represents a juvenile, and possibly male, individual.[1][failed verification][2]

Description[]

The individual of the type specimen has been described as being one metre (3 ft) long.[11]

The describing authors established a unique combination of two traits that in themselves were not unique. The shoulder blade has 81% of the length of the humerus instead of being equally long or much longer, the two prevailing conditions with other compsognathids. The top profiles of the neural spines of the sacral vertebrae are 15% to 27% longer than their bases are long in side view, instead of being much longer as with Mirischia.[1][failed verification]

The granulated structures in the torso were concluded to have been adipocere, corpse wax. They do not show food remains and are therefore unlikely to represent intestines. Also they lack a scale structure. The specimen preserves a "mane" of proto-feathers that ran along its neck and back. Also they covered the arm including the hand up to the claws. This SMF (Slender MonoFilamentous integument) became longer towards the rear, reaching a length of eleven centimetres over the ninth and tenth back vertebrae. These filaments were not branched and had a diameter of about 0.3 millimetre with a hollow core. Skin remains contain a series of nineteen rectangular vertical structures that were interpreted as the follicles of the filaments. Skin muscles would have allowed to erect a mane over the back. Their shrinking in the saline lagoon conditions of the Crato Formation would have caused the mane to have been activated after death, as still shown by the fossil.[1][failed verification]

Unique, 15-centimetre (5.9 in) integumentary structures projected from its sides. The left side shows a pair of flat straight elongated spikes. A similar pair was assumed to have been present on the opposite right side. The upper spike is fifteen centimetres long, the lower one fourteen centimetres. The structures are reinforced by a central sharp longitudinal ridge, 0.1 millimetre wide. Total width is 4.5 millimetres for the upper spike, 2.5 millimetres for the lower with parallel sides which only taper close to the distal end. There is no sign of any ossification. The authors compared this Broad Monofilamentous Integument to those of the standardwing bird-of-paradise. The authors speculate that the ribbon-like shoulder structures might have had display purposes, perhaps being erected in a courtship display. It was also deemed possible that they vibrated and even made a noise. That such a display structure should be present in a juvenile is exceptional. This phenomenon is not known from modern Neornithes but has been reported in Enantiornithes and Zuolong.[1][failed verification] The authors noted that in the more derived group of the Paraves such structures were largely limited to the tail. They suggested this prevented the display structures to limit the aerodynamic capabilities of these volant species. The non-volant compsognathids would in this respect not be hindered by shoulder spikes. That simple filaments could evolve into complex display structures would be an indication that pennaceous feathers were not evolved for display reasons, contrary to what has been often assumed.[1][failed verification][12]

Phylogeny[]

Ubirajara was placed in the Compsognathidae family in 2020, as the sister species of a clade formed by Sinosauropteryx and Compsognathus.[13]

References[]

  1. ^ Jump up to: a b c d e f g h i j Smyth, Robert S. H.; Martill, David M.; Frey, Eberhard; Rivera-Silva, Hector E. & Lenz, Norbert (December 2020). "A maned theropod dinosaur from Brazil with elaborate integumentary structures". Cretaceous Research. doi:10.1016/j.cretres.2020.104686.
  2. ^ Jump up to: a b c d e "A maned theropod dinosaur from Gondwana with elaborate integumentary structures". en.x-mol.com. Retrieved 2021-09-13.
  3. ^ Yarlagadda, Tara. "Paleontologists find tiny, flamboyant dinosaur in ground-breaking discovery". Inverse. Retrieved 2021-09-13.
  4. ^ https://g1.globo.com/ce/ceara/noticia/2021/09/10/museu-da-alemanha-se-recusa-a-devolver-fossil-contrabandeado-do-ceara-diz-sociedade-de-paleontologia.ghtml
  5. ^ Pickrell, John (14 December 2020). "A newfound feathered dinosaur sported fuzz and weird rods on its shoulders". Science News. Society for Science & the Public. Archived from the original on 19 December 2020. Retrieved 19 December 2020.
  6. ^ Vogel, Gretchen (18 December 2020). "Chicken-size dino with a furlike mane stirs ethics debate". Science Magazine. American Association for the Advancement of Science. Archived from the original on 19 December 2020. Retrieved 19 December 2020.
  7. ^ Greshko, Michael (22 December 2020). "One-of-a-kind dinosaur removed from Brazil sparks backlash, investigation". National Geographic. National Geographic Society. Archived from the original on 23 December 2020. Retrieved 23 December 2020.
  8. ^ "Cientistas fazem campanha para que fóssil de Ubirajara jubatus, novo dino brasileiro, seja repatriado". Folha de S. Paulo (in Portuguese). December 18, 2020. Retrieved December 19, 2020.
  9. ^ Grigorakakis, Panos (2020-12-18). "Bizarre New Dinosaur Sported Mane & Shoulder 'Spears'". Medium. Retrieved 2021-09-16.
  10. ^ "TEMPORARY REMOVAL: A maned theropod dinosaur from Gondwana with elaborate integumentary structures". Cretaceous Research: 104686. 2020-12-13. doi:10.1016/j.cretres.2020.104686. ISSN 0195-6671.
  11. ^ Grigorakakis, Panos (2020-12-18). "Bizarre New Dinosaur Sported Mane & Shoulder 'Spears'". Medium. Retrieved 2021-09-16.
  12. ^ "'Like nothing seen in nature before': strange dinosaur has scientists enthralled". The Guardian. 15 December 2020. Retrieved 17 December 2020.
  13. ^ Grigorakakis, Panos (2020-12-18). "Bizarre New Dinosaur Sported Mane & Shoulder 'Spears'". Medium. Retrieved 2021-09-16.
Retrieved from ""