Top fossil discoveries of 2021

Australotitan cooperensis. Image credit: Eromanga Natural History Museum, Artist: Vlad Konstantinov.

The pandemic is not over yet. Despite the fast development of effective vaccines against COVID-19, the virus continued to spread and mutate throughout the last year, with Omicron taking central stage in the last two months. Much of the blame is the unequal distribution of vaccines, a phenomeno described by Tedros Adhanom Ghebreyesus as a “catastrophic moral failure”.

But 2021 was not all bad. Cool new papers about ancient DNA, a billion-year-old freshwater protist, mass extinctions, the abundance of Tyrannosaurus rex, the description of two new spinosaurids from the Wessex Formation of the Isle of Wight, the speed of theropods, and the flower revolution, shapped a remarkable year in paleontology. Among the most striking fossil discoveries are:

  • MOZ-Pv 1221, a new giant titanosaur sauropod from the Upper Cretaceous of Argentina.

Image credit; Jose Luis Carballido/CTyS-UNLaM/AFP

This new giant titanosaur sauropod was discovered in 2012 and is the second taxon from Candeleros Formation, in addition to Andesaurus. The new specimen, identified as MOZ-Pv 1221, includes a sequence of anterior and middle caudal vertebrae, consisting of the first 20 mostly articulated caudal vertebrae and haemal arches plus isolated posterior caudals, pelvis and other appendicular elements. The preserved caudal sequence corresponds to approximately the anterior half of the tail. The neural spines of the anterior caudal vertebrae in MOZ-Pv 1221 are transversely wider than anteroposteriorly long. Compared to other giant titanosaurs, the recovered appendicular bones of MOZ-Pv 1221 are larger than any known titanosaur described to date.

  • Ninjatitan zapatai, the earliest known titanosaur.

Anterior caudal vertebra of Ninjatitan zapatai. From Gallina et al., 2021

Ninjatitan lived 140 million years ago and reached 20 meters in length (65 feet). The firs remains were discovered in 2014 by technician Jonatan Aroca. The holotype (MMCh-Pv228) includes an incomplete anterior–middle dorsal vertebra, a middle dorsal centrum, and anterior caudal centra with the base of neural arches preserved, a complete left scapula, a fragmentary distal femur, and a nearly complete left fibula of a single individual. The generic name honors the Argentine paleontologist Sebastián “Ninja” Apesteguía. The species name refers to Mr. Rogelio “Mupi” Zapata, in recognition for his work as a technician of the Museo Municipal Ernesto Bachman. Despite the fragmentary nature of the new taxon, three derived characters of Ninjatitan support its possition within the clade Titanosauria: 1) presence of procoelous anterior caudal centra; 2) pneumatized neural arch of anterior caudal vertebrae; and 3) position of the acromial process near the glenoid level. The position of Ninjatitan, as a basal titanosaur, extends the origin of this clade by at least 10 Myr.

  • Taytalura alcoberi, the father of lizards.

Taytalura alcoberi.Image credit: Jorge Blanco

The holotype (PVSJ 698), dated to be around 231 million years old, was discovered by a team lead by Ricardo Martínez in 2001 in the Ischigualasto Formation. The tiny skull reached only two centimeters in size, but it was well-preserved. Micro-CT scanning of the skull reveals some features shared with sphenodontians, including a tetraradiate squamosal, differing from the triradiate condition of squamates; a medially curved mandibular symphysis, as in early sphenodontians; and a small coronoid. Taytalura is about 11 million years younger than the oldest known lepidosaurs from Europe, and approximately the same age as the first known crown lepidosaurs in South America. The new finding provides strong evidence that stem lepidosaurs were contemporaneous with the first assemblages of crown lepidosaurs.

  • Australotitan cooperensis, the southern titan.

3-D digital restorations of the holotype (EMF102) of the titanosaurian Australotitan cooperensis (From Hocknull et al. 2021).

The Winton Formation, located in the uppemost unit of the Eromanga Basin, provides an important source of information about the Cretaceous of Australia. In the last two decades, four new dinosaurs were recovered in this area, including Australotitan cooperensis, the largest dinosaur ever found in Australia. The holotype (EMF102), discovered in 2005, comprises a partial left scapula, partial left humerus, complete right humerus, right ulna, both pubic bones and ischia, and partial right and left femora. Three aditional specimens were referred to the genus: EMF164, EMF105, and EMF165. The fragmented femur of specimen EMF164 has a length of 2.146 metres (7.04 feet), similar in size to the femora of Futalognkosaurus and Dreadnoughtus.

  • Ypupiara lopai, the first unenlagiine dromaeosaurid species from Brazil.

Right maxilla of DGM 921-R with details of teeth. Scale bar: 10 mm. From Brum et al., 2021.

Ypupiara lopai from the Maastrichtian of the Bauru Group is the first unenlagiine dromaeosaurid species from Brazil. The holotype (DGM 921-R) includes a partial preantorbital portion of a right maxillary, with three teeth in loci, and a partial posterior portion of a right dentary. The generic name means ‘the one who lives in the water’, an allusion to a Tupian myth about an aquatic creature. The specific name honors Alberto Lopa, the holotype’s discoverer. Ypupiara was found between the 40s and 60s in Peirópolis, near Uberaba, and placed in storage at the National Museum of Brazil. Unfortunately, the fossil was lost when the museum was consumed by a fire on 2 September 2018, but photographs of the specimen survived.

  • Mussaurus and the social behaviour of early sauropodomorphs.

Nest with eggs of Mussaurus patagonicus. Image credit: Credit: Diego Pol.

The discovery of 80 individuals of Mussaurus patagonicus, ranging from embryos to fully-grown adults, and more than 100 eggs, provides the earliest evidence of complex social behaviour. The eggs and nests of Mussaurus were found in three distinct horizons in the middle of the Laguna Colorada Formation. X-ray computed tomography reveals that the eggs were arranged in two or three layers within elongate depressions or trenches that appear to have been purposely excavated. The research team lead by Diego Pol calculated the site’s age at 193 million years, predating previous records of social behavior in dinosaurs by at least 40 My. The researchers also suggest that sociality may have influenced the early success and the first global radiation of sauropods.

  • Stegouros elengassen, an armoured dinosaur from Chile.

Skeletal anatomy of the S. elengassen holotype. From Soto-Acuña et al., 2021.

Stegouros elengassen, a new specimen from the Late Cretaceous Dorotea Formation of southern Chile, offers new evidence that contributes to the understanding of the relationships among the ankylosaurs from Gondwana. The holotype (CPAP–3165) was discovered in 2017 at the lower section of the Dorotea Formation. Stegouros lived about 72 to 75 million years ago, and reached 2 meters in lenght (six feet). The generic name is derived from the the Greek word “stego” (roof ) and the Greek word “uros” (tail) in reference to the covered tail. The specific name “elengassen” comes from an armoured beast in the mythology of the Aónik’enk people.

  • ‘Baby Yingliang’

The new specimen ‘Baby Yingliang’. Credit: Lida Xing

The new specimen (YLSNHM01266), nicknamed Baby Yingliang, is preserved curled inside its egg, with the head positioned ventral to the body. The oviraptorid affinity of Baby Yingliang is supported by several characers, including the crenulated ventral margin of premaxilla; the edentulous skull; the U-shaped mandibular symphysis; and the highly arched dentary. The vertebral column is estimated to have 22 presacral vertebrae. The pubis points posteroventrally, similar to that of modern birds, althought it is unclear how much of its orientation is genuine. The almost complete skeleton is ∼23.5 cm in total length. It was found in Shahe Industrial Park in Ganzhou City and acquired by the director of Yingliang Group, Mr Liang Liu. It was stored in Yingliang Stone Nature History Museum until the museum staff discovered it.

References:

Otero A, Carballido JL, Salgado L, Canudo JI, Garrido AC (2021), Report of a giant titanosaur sauropod from the Upper Cretaceous of Neuquén Province, Argentina, Cretaceous Research https://doi.org/10.1016/j.cretres.2021.104754

Pablo Ariel Gallina, Juan Ignacio Canale, & José Luis Carballido (2021).The earliest known titanosaur sauropod dinosaur. Ameghiniana58(1), 35–51 http://dx.doi.org/10.5710/AMGH.20.08.2020.3376

Martínez, R.N., Simões, T.R., Sobral, G. et al. A Triassic stem lepidosaur illuminates the origin of lizard-like reptiles. Nature 597, 235–238 (2021). https://doi.org/10.1038/s41586-021-03834-3

Hocknull SA, Wilkinson M, Lawrence RA, Konstantinov V, Mackenzie S, Mackenzie R. 2021. A new giant sauropod, Australotitan cooperensis gen. et sp. nov., from the mid-Cretaceous of Australia. PeerJ 9:e11317 https://doi.org/10.7717/peerj.11317

Brum, Arthur Souza, Pêgas, Rodrigo Vargas, Bandeira, Kamila Luisa Nogueira, Souza, Lucy Gomes de, Campos, Diogenes de Almeida, & Kellner, Alexander Wilhelm Armin. (2021). A new Unenlagiinae (Theropoda: Dromaeosauridae) from the Late Cretaceous of Brazil. https://doi.org/10.1002/spp2.1375

Pol, D., Mancuso, A.C., Smith, R.M.H. et al. Earliest evidence of herd-living and age segregation amongst dinosaurs. Sci Rep 11, 20023 (2021). https://doi.org/10.1038/s41598-021-99176-1

Soto-Acuña, S., Vargas, A.O., Kaluza, J. et al. Bizarre tail weaponry in a transitional ankylosaur from subantarctic Chile. Nature (2021). https://doi.org/10.1038/s41586-021-04147-1

Waisum Ma et al. (2021). An exquisitely preserved in-ovo theropod dinosaur embryo sheds light on avian-like prehatching postures, iScience  DOI: https://doi.org/10.1016/j.isci.2021.103516

 

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