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Aratasaurus

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Aratasaurus
Temporal range: Early Cretaceous (late Aptian–early Albian?)
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Holotype femur and tibia
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Coelurosauria
Genus: †Aratasaurus
Sayão et al., 2020
Species:
†A. museunacionali
Binomial name
†Aratasaurus museunacionali
Sayão et al., 2020

Aratasaurus is an extinct genus of basal coelurosaurian theropod dinosaur from the Early Cretaceous (Aptian) Romualdo Formation of Brazil. The genus contains a single species, A. museunacionali, known from a partial right leg. Aratasaurus represents the only tetrapod fossil known from the lower levels of the Romualdo Formation.

Discovery and naming

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Holotype leg bones before preparation

The Aratasaurus holotype, MPSC R 2089, was discovered in 2008 in Mina Pedra Branca, a plaster mine representing outcrops of the lower Romualdo Formation near Santana do Cariri in Ceará state of northeastern Brazil.[1] The specimen consists of a partial articulated right leg, including the distal end of the femur, the proximal end of the tibia, part of metatarsals I–IV, several phalanges, and three pedal unguals. The specimen represents only part of the preserved individual, but the remainder was broken and lost during mining activity.[2]

After its discovery, the fossil was taken to the Plácido Cidade Nuvens Museum of Paleontology to be prepared and described. Between 2008 and 2016, histological sample slices were made of the bones to observe the microscopic tissues. In 2016, the specimen was deposited at the National Museum of Brazil.[1] On September 2, 2018, the museum was heavily damaged in a fire,[3] but the area where the holotype was stored remained intact.[2]

In 2020, Sayão and colleagues described Aratasaurus museunacionali as a new genus and species of early coelurosaurian theropod based on these fossil remains. The generic name, Aratasaurus, combines the Tupi words "ara", meaning "born", and "atá", meaning "fire", with the Greek "σαῦρος" ("sauros"), meaning "lizard". The specific name, museunacionali, honours the fire-devastated National Museum of Brazil, which is the country's oldest science institution.[2] The full binomial name is intended to mean "the dinosaur born from the National Museum fire".[4]

Description

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Speculative life restoration

As a coelurosaur, Aratasaurus likely had some form of feather covering, although no integument was preserved in the holotype. Some of the Aratasaurus bones—especially the tibia—compare favorably to Zuolong, a theropod from the Late Jurassic Shishugou Formation of China.[5] The pes is more similar to the Jurassic theropods Aorun and Tanycolagreus. Based on osteohistological studies, Sayão et al. (2020) proposed that the holotype of Aratasaurus represents a juvenile or young adult that was about four years old at the time of its death. It has an estimated body length of 3.12 metres (10.2 ft) and a body weight of around 34.25 kilograms (75.5 lb). However, since the individual was not mature, it would have been able to grow larger.[2]

Classification

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In their phylogenetic analyses, Sayão et al. (2020) recovered Aratasaurus as the sister taxon to Zuolong, in the basalmost clade of coelurosaurs. Their results are displayed in the cladogram below:[2]

Coelurosauria

Paleoecology

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Environmental reconstruction of the Romualdo Formation, including Irritator in the foreground and pterosaurs and a small theropod in the background

Aratasaurus is known from the Romualdo Formation of Brazil, which dates to the Aptian–Albian ages of the early Cretaceous period.[6][7] It is the only theropod—and the only fossil tetrapod—currently known from the base of the formation, which has an estimated date of 115 Ma.[1] However, at least three non-avian theropods have been named from the upper layers, including the spinosaurine Irritator challengeri and the coelurosaurs Santanaraptor placidus and Mirischia asymmetrica. This formation is very well known for its diverse pterosaur fauna, including abundant well-preserved anhanguerians and tapejarids.[8][9] Several fossil crocodylomorphs, fish, and turtles are also known from the formation.[2][10]

See also

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References

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  1. ^ a b c Van Brunnersum, Melissa Sou-Jie (July 10, 2020). "Scientists discover 115-million-year-old fossil of new dinosaur species in Brazil". DW.
  2. ^ a b c d e f Juliana Manso Sayão; Antônio Álamo Feitosa Saraiva; Arthur Souza Brum; Renan Alfredo Machado Bantim; Rafael Cesar Lima Pedroso de Andrade; Xin Cheng; Flaviana Jorge de Lima; Helder de Paula Silva; Alexander W. A. Kellner (2020). "The first theropod dinosaur (Coelurosauria, Theropoda) from the base of the Romualdo Formation (Albian), Araripe Basin, Northeast Brazil". Scientific Reports. 10 (1): Article number 10892. Bibcode:2020NatSR..1010892S. doi:10.1038/s41598-020-67822-9. PMC 7351750. PMID 32651406.
  3. ^ "Rio's 200-year-old National Museum hit by massive fire". Reuters. 2 September 2018. Archived from the original on 3 September 2018. Retrieved 2 September 2018.
  4. ^ Wojdon, Joanna; Wiśniewska, Dorota, eds. (2021-07-30). "10. On Fire, under Fire: Public Reactions to the Destruction of the Brazilian National Museum". Public in public history. Global Perspectives on Public History. New York: Routledge. ISBN 978-0-367-64103-0.
  5. ^ Choiniere, Jonah N.; Clark, James M.; Forster, Catherine A.; Xu, Xing (2010-12-02). "A basal coelurosaur (Dinosauria: Theropoda) from the Late Jurassic (Oxfordian) of the Shishugou Formation in Wucaiwan, People's Republic of China". Journal of Vertebrate Paleontology. 30 (6): 1773–1796. Bibcode:2010JVPal..30.1773C. doi:10.1080/02724634.2010.520779. ISSN 0272-4634. S2CID 86543963.
  6. ^ Martill, D.M (2007). "The age of the Cretaceous Santana Formation fossil Konservat Lagerstätte of north-east Brazil: a historical review and an appraisal of the biochronostratigraphic utility of its palaeobiota". Cretaceous Research. 28 (6): 895–920. Bibcode:2007CrRes..28..895M. doi:10.1016/j.cretres.2007.01.002. Retrieved 2018-10-06.
  7. ^ Heimhofer, Ulrich; Hochuli, Peter-A. (2010). "Early Cretaceous angiosperm pollen from a low-latitude succession (Araripe Basin, NE Brazil)". Review of Palaeobotany and Palynology. 161 (3–4): 105–126. doi:10.1016/j.revpalbo.2010.03.010.
  8. ^ Cerqueira GM, Santos MA, Marks MF, Sayão JM, Pinheiro FL (2021). "A new azhdarchoid pterosaur from the Lower Cretaceous of Brazil and the paleobiogeography of the Tapejaridae". Acta Palaeontologica Polonica. 66. doi:10.4202/app.00848.2020..
  9. ^ Duque, Rudah R. C.; Pinheiro, Felipe L.; Coutinho, Donatila Luiza Carvalho; Barreto, Alcina Magnólia Franca (2023-07-01). "New pterosaur specimens with geographic and stratigraphic procedence from the Romualdo Formation (Lower Cretaceous, Araripe Basin, Brazil)". Journal of South American Earth Sciences. 127: 104408. doi:10.1016/j.jsames.2023.104408. ISSN 0895-9811.
  10. ^ Kellner, Alexander W. A.; Campos, Diogenes de Almeida (1999-09-01). "Vertebrate paleontology in Brazil — a review". Episodes Journal of International Geoscience. 22 (3): 238–251. doi:10.18814/epiiugs/1999/v22i3/012.

Further reading

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