Ubirajara jubatus

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Proposed holotype specimen 2023 - Abertura da caixa do fossil Ubirajara jubatus.jpg
Proposed holotype specimen

"Ubirajara" ("lord of the spear") is an informal genus of compsognathid theropod that lived during the early Cretaceous period in what is now Brazil. The manuscript describing it was available online pre-publication but was never formally published and, as a consequence, both genus and species name are considered invalid and unavailable. [1] It is known by a single species, "Ubirajara jubatus", recovered from the Crato Formation. It was described as the first Gondwanan non-avian theropod dinosaur discovered with preserved integumentary structures. 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 [2] The taxon was informally named in 2020 in a now-withdrawn in-press academic paper. The description caused controversy due to the fossil having been apparently illegally smuggled from Brazil. In July 2022, Germany agreed to return the fossil to Brazil after a legitimate export permit could not be found. The name "Ubirajara jubatus" was removed from ZooBank in November 2022, which means it no longer has any nomenclatural significance. [1]

Contents

History of discovery

Skeletal reconstruction showing known elements Ubirajara jubatus skeletal.jpg
Skeletal reconstruction showing known elements

Workers recovered a number of fossils from a chalk quarry located between Nova Olinda and Santana do Cariri. One of the recovered 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. The specimen, 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 consists of 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 also 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. [3] [ failed verification ]

The genus name "Ubirajara" was erected by Robert S. H. Smyth, David Michael Martill, Eberhard Frey, Hector Eduardo Rivera-Silva and Norbert Lenz in December 2020. [3] [ failed verification ] The generic name means "Lord of the Spear" in the local Tupi language, in reference to the elongate shoulder filaments. The informal specific name, "jubatus", means "maned" in Latin, referring to the preserved integument on its back. [4] However, since the paper was never published, the name "Ubirajara jubatus" is unavailable. [1]

Officials with the specimen's slab and counterslab during a ceremony after its return to Brazil in 2023 12 06 2023 - Cerimonia de repatriacao do fossil Ubirajara jubatus (52969689747).jpg
Officials with the specimen's slab and counterslab during a ceremony after its return to Brazil in 2023

The fossil was acquired in 1995 by the State Museum of Natural History Karlsruhe (SMNK) and moved to Germany after an export permit was allegedly obtained. [3] [ failed verification ] [5] The 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. [6] [7] [8] As a result, Brazilian scientists campaigned for the repatriation of the fossils. [9]

Due to the ethical issues involving the potentially illegal transfer of the fossil from Brazil to Germany, the paper describing the specimen was "temporarily removed" only a few days after being made available online "in press" prior to formal publication. [8] [10] The article was later withdrawn in September 2021. [11] The case has been labeled as an instance of scientific colonialism. [12] [13] [14] [15]

In July 2022, following an extensive social media campaign, the SMNK agreed to return the specimen to Brazil after their investigation failed to find legitimate export permits. [16] The specimen has been reported as repatriated in June 2023. [17]

On 18 November 2022, the records of the names "Ubirajara jubatus", as well as their publication records, were removed from ZooBank, and a 2023 review noted that "Ubirajara jubatus" is an unavailable name with no nomenclatural significance, but not specifically a nomen nudum . [1]

It has also been noted that the phylogenetic matrix containing the specimen has never been made available, raising doubts about the claimed affinities of the specimens. [1]

On June 13, 2023, the fossil was repatriated to the claimant country (Brazil), and delivered to the Plácido Cidade Nuvens Paleontology Museum, equipment of the Regional University of Cariri (Urca) [18]

Description

Life restoration Ubirajara jubatus revised.png
Life restoration

In life, the fossil individual would have been approximately 1 metre (3.3 ft) long. [4]

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 . [3] [ 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. [3] [ 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 . [3] [ failed verification ] The authors noted that in the more derived group of the Paraves, such structures are 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. [3] [ failed verification ] [19]

Phylogeny

The specimen was placed in the Compsognathidae family in 2020, as the sister species of a clade formed by Sinosauropteryx and Compsognathus . [4] This phylogeny was criticized since it cannot be properly scientifically tested or replicated at the moment because the data supporting it were never made available. [1]

Compsognathidae

See also

Related Research Articles

<span class="mw-page-title-main">Feather</span> Body-covering structure of birds

Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and a premier example of a complex evolutionary novelty. They are among the characteristics that distinguish the extant birds from other living groups.

<i>Sinosauropteryx</i> Extinct genus of dinosaurs

Sinosauropteryx is a compsognathid dinosaur. Described in 1996, it was the first dinosaur taxon outside of Avialae to be found with evidence of feathers. It was covered with a coat of very simple filament-like feathers. Structures that indicate colouration have also been preserved in some of its feathers, which makes Sinosauropteryx the first non-avialian dinosaurs where colouration has been determined. The colouration includes a reddish and light banded tail. Some contention has arisen with an alternative interpretation of the filamentous impression as remains of collagen fibres, but this has not been widely accepted.

<span class="mw-page-title-main">Coelurosauria</span> Clade of dinosaurs

Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs.

<i>Beipiaosaurus</i> Extinct genus of dinosaurs

Beipiaosaurus is a genus of therizinosauroid theropod dinosaurs that lived in Asia during the Early Cretaceous in the Yixian Formation. The first remains were found in 1996 and formally described in 1999. Before the discovery of Yutyrannus, Beipiaosaurus were among the heaviest dinosaurs known from direct evidence to be feathered. Beipiaosaurus is known from three reported specimens. Numerous impressions of feather structures were preserved that allowed researchers to determine the feathering color which turned out to be brownish.

<span class="mw-page-title-main">Feathered dinosaur</span> Dinosaur with feathers

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<i>Mirischia</i> Extinct genus of dinosaurs

Mirischia is a small genus of compsognathid theropod dinosaur from the Albian stage of Brazil.

<i>Alxasaurus</i> Therizinosauroid dinosaur genus from the Early Cretaceous

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<i>Juravenator</i> Extinct genus of dinosaurs

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<i>Santanaraptor</i> Extinct genus of dinosaurs

Santanaraptor is a genus of tyrannosauroid theropod dinosaur that lived in South America during the Early Cretaceous, about 112 million years ago.

<span class="mw-page-title-main">Compsognathidae</span> Extinct family of dinosaurs

Compsognathidae is a family of coelurosaurian theropod dinosaurs. Compsognathids were small carnivores, generally conservative in form, hailing from the Jurassic and Cretaceous Periods. The bird-like features of these species, along with other dinosaurs such as Archaeopteryx inspired the idea for the connection between dinosaur reptiles and modern-day avian species. Compsognathid fossils preserve diverse integument — skin impressions are known from four genera commonly placed in the group, Compsognathus, Sinosauropteryx, Sinocalliopteryx, and Juravenator. While the latter three show evidence of a covering of some of the earliest primitive feathers over much of the body, Juravenator and Compsognathus also show evidence of scales on the tail or hind legs. "Ubirajara jubatus", informally described in 2020, had elaborate integumentary structures on its back and shoulders superficially similar to the display feathers of a standardwing bird-of-paradise, and unlike any other non-avian dinosaur currently described.

<i>Sinocalliopteryx</i> Extinct genus of dinosaurs

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<i>Yutyrannus</i> Genus of proceratosaurid dinosaur from the Early Cretaceous period

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<i>Kulindadromeus</i> Extinct genus of dinosaurs

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<span class="mw-page-title-main">State Museum of Natural History Karlsruhe</span> Natural history museum in Baden-Württemberg, Germany

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References

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