In as we speak’s weblog publish we have a look at the dwarf nodosaurid Patagopelta (P. cristata), which was formally named and described earlier this month.
A brand new, very small, armoured dinosaur has been named and described from fossils present in Argentina. The dinosaur which measured round 2 to 2.3 metres in size (based mostly on the scale of the femur), means that some members of the Nodosauridae in Gondwana turned smaller within the Late Cretaceous, maybe as armoured dinosaurs in South America had been beneath evolutionary stress from different ornithischians and titanosaurs.
Dwarf Nodosaurid Patagopelta
Fragmentary stays of Late Cretaceous armoured dinosaurs are identified from Chile and Argentina, however little work had been undertaken to evaluate these specimens and to overview their phylogeny and taxonomic relationship with different members of the Ankylosauria clade from North America and elsewhere on the planet.
Writing within the ” Journal of Systematic Palaeontology”, the researchers led by Facundo Riguetti, a CONICET doctoral fellow, reassessed the identified ankylosaur materials at the side of another not too long ago discovered fossils and, in consequence, they had been capable of set up a brand new nodosaurid species from bones and a single tooth present in sediments of the Allen Formation (Campanian–Maastrichtian) in Salitral Moreno, Río Negro Province (northern Patagonia).
Patagopelta cristata
The dinosaur’s genus identify interprets as “Patagonian defend” while the trivial identify derives from the Latin for crest – a reference to the diagnostic crests on each the anterior floor of the femur and the lateral osteoderms of the cervical rings.
Dr Riguetti commented:
“The significance of the examine lies in the truth that Patagopelta is the primary species of Ankylosauria described for the continental territory of Argentina, which fills the prevailing hole for this group and provides a brand new thyreophoran to the only a few incomplete and indeterminate stays identified for our nation from one of these ornithischian dinosaur.”
The Proper Femur
The perfect-preserved fossil factor is the suitable femur, which is full and exhibits typical anatomical traits related to the Nodosauridae. This bone together with the distinctive cervical osteoderms led to the erection of this new species. Because the femur is just 25 cm in size and bone histology suggests an grownup animal, the researchers conclude that Patagopelta was a dwarf type of armoured dinosaur.
Co-author Sebastián Apesteguía, a CONICET researcher, defined:
“For an armoured dinosaur, Patagopelta is extraordinarily small. As a result of measurement of the femur, solely 25 centimetres in size, we estimate that the animal should have been between two and three meters lengthy, whereas, generally, ankylosaurs are medium-sized or giant animals, with a mean size of between 4 and 5 metres.”
A Faunal Trade Throughout the Americas
Though it’s thought that the Nodosauridae advanced within the Northern Hemisphere, in direction of the tip of the Cretaceous (Campanian – Maastrichtian), a land bridge existed between North America and South America that permitted a faunal alternate. Titanosaurs migrated north, which explains why fossils of titanosaurs corresponding to Alamosaurus happen within the USA. Ornithischian dinosaurs corresponding to hadrosaurs and nodosaurids moved south.
The picture above exhibits a typical Late Cretaceous titanosaur, for fashions of Late Cretaceous dinosaurs together with titanosaurs and armoured dinosaurs: CollectA Prehistoric Life Fashions.
Sebastián Apesteguía added:
“That’s the reason in South America we solely look forward to finding animals like Patagopelta in rocks from the Late Cretaceous, simply earlier than the worldwide extinction of the dinosaurs occurred.”
Dwarfism in Late Cretaceous South American Thyreophora
The dimensions of Patagopelta together with the not too long ago described Stegouros (Soto-Acuña et al, 2021)*, from southernmost Chile, means that armoured dinosaurs in South America could have step by step develop into smaller. This trait isn’t identified in members of the Thyreophora described from different elements of the world. Palaeontologists have speculated that maybe competitors from titanosaurs and the migration of hadrosaurs into South America might need led to armoured dinosaurs adapting to completely different ecological niches to keep away from competitors. By being smaller these animals wanted fewer assets than bigger, contemporaneous herbivorous dinosaurs.
It has additionally been urged that the geology of Patagonia the place the fossils of Patagopelta had been discovered would possibly present a clue to the dwarfism. Geologists are conscious of a number of Late Cretaceous marine transgressions within the area. This might need led to the institution of an island archipelago with dinosaurs dwelling on these small islands step by step develop into smaller as a consequence of a shortage of assets (the “island rule”).
Tracks of Dwarf Ankylosaurs
Members of the Patagopelta analysis staff had beforehand described tracks of dwarf ankylosaurs, presumably affected by comparable circumstances, preserved in Higher Cretaceous deposits in Bolivia.
*To learn All the things Dinosaur’s 2021 article concerning the discovery of Stegouros: New Armoured Dinosaur from Chile.
All the things Dinosaur acknowledges the help of a media launch from Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) within the compilation of this text.
The scientific paper: “A brand new small-bodied ankylosaurian dinosaur from the Higher Cretaceous of North Patagonia (Río Negro Province, Argentina)” by Facundo Riguetti, Xabier Pereda-Suberbiola, Denis Ponce, Leonardo Salgado, Sebastián Apesteguía, Sebastián Rozadilla and Victoria Arbour printed within the Journal of Systematic Palaeontology.