Meraxes gigas. Image credit: J. Gonzalez
It was the season of Light, it was the season of Darkness. The year began with the War between Russia and Ukraine, and the subsequent humanitarian crissis. Global fuel and food prices soared because of the conflict. Mega-fires were exacerbated by drought, and anthropogenic climate change. The State of the Cryosphere Report 2022 indicates that complete loss of Arctic sea ice in summer is now inevitable, which, combined with heat waves in Antarctica will lead to the irreversible sea-level rise. Meanwhile, the International Union for Conservation of Nature (IUCN) added 66 new species to its Red List.
But 2022 was not all bad. Cool new papers about the oldest animal, an Edmontosaurus “mummy”, the rise of dinosaurs and climate change, world’s oldest heart, world’s oldest brain, world’s oldest DNA, and a graveyard, shapped a remarkable year in paleontology. Among the most striking fossil discoveries are:
Dearc sgiathanach.
Postcranial skeleton and dentition of Dearc sgiathanach. From Jagielska et al., 2022
Discovered in 2017 by Amelia Penny, the holotype (NMS G.2021.6.1-4), a well preserved, articulated, skeleton, was found at Rubha nam Brathairean (Brothers’ Point), Isle of Skye, in north-west Scotland, in the Lonfearn Member of the Lealt Shale Formation (Bathonian, Middle Jurassic). The specimen is almost complete with the exception of the anterior and dorsal portions of the cranium, the end of the tail, hindlimbs elements, and parts of the wings. The name comes from the Scottish Gaelic language and has a double meaning: “winged reptile” and “reptile from Skye.” Phylogenetic analysys places Dearc sgiathanach within the clade Angustinaripterini. The new specimen suggests that many “pterodactyloid” features convergently evolved in other groups, and hightlights that the Middle Jurassic was a time of increasing diversification in pterosaur history.
First Triassic records of pterosaurs in the southern hemisphere
Pachagnathus and Yelaphomte. Image credit: Jorge Blanco
The description of two new specimens from Quebrada del Barro Formation in north-western Argentina are the first unequivocal Triassic records of pterosaurs in the southern hemisphere. Previous to this new work, the only record of a Triassic pterosaur in southern hemisphere was Faxinalipterus minima, from the Caturrita Formation in southern Brazil, although now is considered as a basal Ornithodira.
Yelaphomte praderioi was a small pterosaur. The holotype (PVSJ:914) is represented by a partial rostrum with the anterior part of both maxillae and palatine, and the posterior portion of both premaxillae. Pachagnathus benitoi was a moderate-sized pterosaur. The holotype (PVSJ:1080) is a partial mandibular symphysis lacking anterior end, preserving one tooth and three alveoli from the the left side, and the roots of three teeth and two alveoli from the right side.
Pterosaurs and the origin of feathers
Scanning electron micrographs of melanosomes in the soft tissues of MCT.R.1884
A new specimen of an adult Tupandactylus imperator, a tapejarid pterosaur from north-eastern Brazil, preserves extensive soft tissues which provides more evidence that pterosaurs had feathers. The new specimen (MCT.R.1884) comprises the posterior portion of the cranium and the remains of a soft tissue cranial crest preserved on five separate slabs. Two types of fibrous integumentary structures were present. The monofilaments (approximately 30 mm long and 60–90 μm wide) resemble those present in the anurognathid Jeholopterus ningchengensis and the ornithischian dinosaur Tianyulong. The most striking feature is the presence of fossil melanosomes with diverse morphologies that supports the hypothesis that the branched integumentary structures in pterosaurs are feathers. The fossil, originally poached from an undetermined outcrop of the Early Cretaceous Crato Formation, was in privated hands for an unknown period of time and later deposited at the Royal Belgian Institute of Natural Sciences (RBINS). The fossil was repatriated to Brazil early this year.
Abditosaurus kuehnei.
Fossil elements of Abditosaurus kuehnei collected during the 2012-2014 excavations. Image credit: Rubén Contreras. From Vila et al., 2022.
Abditosaurus kuehnei from the Late Cretaceous of Catalonia is the most complete titanosaur skeleton discovered in Europe so far. The specimen reached 17,5 meters in length (57 ft) with a body mass of 14,000 kg. The holotype, an associated, semi-articulated, partial skeleton, includes several isolated teeth, 12 cervical vertebrae, 7 dorsal vertebrae, 3 chevrons, scapular and pelvic bones, right tibia, parts of the femurs and a complete humerus. Phylogenetic analyses indicates that Abditosaurus is a saltasaurid lithostrotian titanosaur. Saltasaurinae, a clade from South America and Africa, includes Neuquensaurus, Saltasaurus and Paralititan. The arrival of Abditosaurus to Europe via a dispersal event from Africa ocurred after a regressive event during the Early Maastrichtian (70.6 Ma) that affected the central Tethyan margin and northern Africa.
Maip macrothorax
Maip macrothorax. Image credit: Agustín Ozán
Maip macrothorax is a large-bodied megaraptorid from lower Maastrichtian Chorrillo Formation in Santa Cruz Province, Argentina. The holotype (MPM 21,545) includes the axis (only lacking both prezygapophyses and its right postzygapophysis), several dorsal and caudal vertebrae, three incomplete cervical ribs, numerous incomplete or fragmentary dorsal ribs, numerous gastral elements, left coracoid, distal end of a second metatarsal, and fragments of the scapula. The generic name, Maip, is derived from an evil entity in Aonikenk mythology that represents “the shadow of the death”. The specific name, macro, derives from the Greek word makrós (meaning long), and the Latin word thorax (meaning chest) in reference to its wide thoracic cavity (which has, approximately, more than 1.20 m width). The specimen was discovered in 2019, but due the outbreak of the COVID-19 pandemic in early 2020 the dig was temporarily interrupted.
Meraxes gigas
Reconstruction of the skeleton of Meraxes. From Canale et al., 2022
Meraxes gigas, a new specimen from the Upper Cretaceous of northern Patagonia, Argentina, is the most complete carcharodontosaurid ever found and provides new information about the skull length in Giganotosaurus. The holotype (MMCh-PV 65) is represented by a nearly complete skull without mandibles, pectoral and pelvic girdles, fore- and hindlimbs, fragments of cervical and dorsal vertebrae, complete sacrum, and proximal and middle caudal vertebral series. The first remains were discovered in 2012 in the Upper Cretaceous Huincul Formation of northern Patagonia, Argentina. The new specimen weighed more than 4 tons and measured up to 11 meters (36 feet) long. Histological analysis indicates that this dinosaur was an adult of 45-53 years of age at death. The skull of Meraxes is profusely ornamented and has a total length of 127 cm. This is the most complete cranium of any Carcharodontosaurinae. Applying scaling equations and measurements taken from Meraxes, the team lead by Dr. Juan Canale from the Museo Paleontológico Ernesto Bachmann, has estimated the size of the Giganotosaurus skull. The results indicate a length of 163 cm, one of the biggest theropod skulls ever found.
Jakapil kaniukura
Jakapil kaniukura. Image credit: Pepe Mateos/Agencia Telam
Jakapil kaniukura is the first definitive thyreophoran species from Argentina. The first remains were found in 2014, in the upper beds of the Candeleros Formation at the ‘Rinconada de la Piedra Blanca’ in Rio Negro Province, Argentina. The genus name Jakapil (Ja-Kapïl: shield bearer), comes from the ‘gananah iahish’, Puelchean or northern Tehuelchean language. The specific epithet, comprising kaniu (crest) and kura (stone), comes from the Mapudungun language and refers to the diagnostic ventral crest of the mandible. The holotype (MPCA-PV-630), with an estimated living mass of 4-7kg (9-15lb), is a partial skeleton of a subadult individual that includes fragmentary cranial bones, a nearly complete left lower jaw, partial vertebral elements, a complete dorsal rib, a partial coracoid, a nearly complete left scapula, a partial right scapula, two partial humeri, a possible partial right ulna, and more than forty osteoderms.
Elemgasem nubilus
Elemgasem nubilus. Image credit: Abel Germán Montes
Elemgasem nubilus, from the Portezuelo Formation of Argentina, is the first abelisaurid from the Turonian–Coniacian interval. The new specimen increases the diversity of this clade at a time of significant turnover in the tetrapod fauna of South America, marked by global climate change, and mass extinction events recorded worldwide in the marine realm. The holotype (MCF-PVPH-380), discovered in 2002, includes several axial and appendicular elements. Elemgasem measured about 4 meters (13 feet) long. The genus name refers to the Tehuelche god Elemgasem, the ‘owner’ of the animals and founder of the northern Tehuelche people. The specific name nubilus comes from the Latin ‘foggy days’ in reference to the climatic conditions during the palaeontological expedition when this specimen was discovered.
Natovenator polydontus
Natovenator polydontus. Image credit: Yusik Choi
Natovenator polydontus, a new theropod dinosaur from the Upper Cretaceous of Mongolia, was a small swimmer. The holotype (MPC-D 102/114) is a mostly articulated skeleton with a nearly complete skull, with anatomical characteristics very similar to the aquatic adaptations in Halszkaraptor. The most striking feature is the configuration of its articulated dorsal ribs that indicates that Natovenator had a dorsoventrally flattened and streamlined body, similar to penguins. The generic name is derived from the Latin nato (swim) and venator (hunter), in reference to to the hypothesized swimming behaviour and diet of the new taxon. Thespecific name polydontus, from the Greek polys (many) and odous (tooth) refers to the presence of the unusually number of teeth of the new specimen.
Patagopelta cristata
Digitized reconstruction of Patagopelta. Image credit: CONICET
Patagopelta cristata, a new nodosaurid ankylosaur from the Allen Formation (Campanian–Maastrichtian), Rio Negro Province, Argentina, is the first species of ankylosaurus described for Argentina. The new specimen also offers new evidence that contributes to the understanding of the relationships among the ankylosaurs from Gondwana. The new specimen lived about 70 million years ago. The body length estimated is ∼2 meters (comparable in size with the nodosaurid Struthiosaurus from the Late Cretaceous of Europe). The generic name is derived from the word ‘Patago’ (referring to the Argentinian Patagonia) and ‘pelta’ (shield in Greek), in reference to the presence of a large number of osteoderms covering the dorsal surface of the body. The specific name ‘cristata‘ (crest in Latin) refers to the presence of crests on the anterior surface of the femur and the lateral osteoderm of the cervical rings.
References:
Martínez, R.N., Andres, B., Apaldetti, C. and Cerda, I.A. (2022), The dawn of the flying reptiles: first Triassic record in the southern hemisphere. Pap Palaeontol, 8: e1424.https://doi.org/10.1002/spp2.1424
Canale, J.I. et al., New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction. Current Biology (2022). doi:10.1016/j.cub.2022.05.057
Aranciaga Rolando, A.M., Motta, M.J., Agnolín, F.L. et al. A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina. Sci Rep 12, 6318 (2022). https://doi.org/10.1038/s41598-022-09272-z
Lee, S., Lee, YN., Currie, P.J. et al. A non-avian dinosaur with a streamlined body exhibits potential adaptations for swimming. Commun Biol 5, 1185 (2022). https://doi.org/10.1038/s42003-022-04119-9
Letters from Gondwana. 