This year (2021), has been another bumper year for dinosaur discoveries with over forty new species of dinosaur described, including several from the British Isles such as Pendraig (P. milnerae) from Wales and four new dinosaurs described from fossil finds on the Isle of Wight (Brighstoneus, Ceratosuchops, Riparovenator and Vectiraptor).

New genera are erected based on new fossil discoveries. In addition, a new dinosaur genus or species can be established based on a revision of existing and previously studied fossil material. A new genus of Late Cretaceous, Brazilian titanosaur was announced this year, based on fragmentary remains that had previously been assigned to a titanosaur that roamed Argentina. Time for Arrudatitan maximus to step out of the shadows.

The fragmentary fossil bones previously assigned to the Argentinian titanosaur Aeolosaurus maximus and now defined as new Brazilian titanosaur taxon Arrudatitan maximus. Picture credit: Silva Junior et al.

Picture credit: Silva Junior et al

Aeolosaurus maximus

The Aeolosaurus genus was erected by the Argentinian palaeontologist Jaime Powell in 1987 when the first species was named (A. rionegrinus). It was a widespread genus known from numerous individuals collected from Upper Cretaceous deposits, most notably the Angostura Colorada Formation in Río Negro Province, but dinosaur fossils collected from the Bajo Barreal, Los Alamitos and Allen Formations of Argentina have also been assigned to this genus.

The Brazilian fossil remains that led to the erection of the species Aeolosaurus maximus in 2011, have always been regarded as somewhat of an outlier when compared to Aeolosaurus fossil remains discovered in Argentina. A. maximus was described based on vertebrae, ribs, a left ischium, a fragmentary scapula and elements from the limbs including a left femur discovered in 1997 eroding out of an outcrop of the Adamantina Formation in the state of São Paulo state south-eastern Brazil.

Researchers who included Julian Silva Junior (Universidade de São Paulo), reassessed the fossil material following a cladistic analysis in 2019 that challenged the taxonomic placement. Writing in “Historical Biology”, the scientists have confirmed the assertion expressed previously that the Brazilian fossil material represents a distinct genus and the fossils ascribed to Aeolosaurus maximus have been reassigned to the new dinosaur species Arrudatitan maximus.

Although the size of A. maximus remains uncertain, based on the femur length of 1.55 metres, palaeontologists estimate that this titanosaur may have reached a length of around 15 metres.

Commenting on the revision, lead author of the scientific paper, doctoral student Julian Silva Junior stated:

“When analysing the caudal vertebrae, we found that they were different to those assigned to Aeolosaurus and these characteristics served to establish a diagnosis to propose a new genus.”

2021 – A Good Year for Titanosaur Discoveries

Several new titanosaur genera have been erected this year including Menucocelsior (M. arriagadai) and Ninjatitan (N. zapatai), which is the oldest titanosaur known to science.

Everything Dinosaur’s list of new titanosaurs named in 2021

• Arackar licanantay a titanosaur from the Upper Cretaceous Hornitos Formation of Chile.
• Arrudatitan maximus from the Upper Cretaceous Adamantina Formation of south-eastern Brazil.
• Australotitan cooperensis a titanosaur from the Winton Formation of Queensland, Australia.
• Garrigatitan meridionalis from the Upper Cretaceous Argiles Rutilantes Formation of south-eastern France.
• Hamititan xinjiangensis from the Lower Cretaceous Shengjinkou Formation of north-western China which was coeval with the euhelopodid sauropod Silutitan (S. sinensis) which was also scientifically described in 2021.
• Menucocelsior arriagadai from the Upper Cretaceous Allen Formation of Argentina.
• Ninjatitan zapatai the earliest titanosaur known to date described from fossils found in the Lower Cretaceous Bajada Colorada Formation of Argentina.

To read blog posts about some of these newly described titanosaurs:

A new species of titanosaur from the Atacama Desert of northern Chile (Arackar licanantay): A New Titanosaur from Chile – Arackar licanantay.

Australian dinosaur “Cooper” named: “Cooper” – Australotitan cooperensis.

Our article on Hamititan xinjiangensis and Silutitan sinensis: Two New Sauropods from North-western China.

To read the Everything Dinosaur blog post about the earliest titanosaur known to science: Ninjatitan zapatai the Earliest Titanosaur.

The scientific paper: “Reassessment of Aeolosaurus maximus, a titanosaur dinosaur from the Late Cretaceous of Southeastern Brazil” by Julian C. G. Silva Junior, Agustín G. Martinelli, Fabiano V. Iori, Thiago S. Marinho, E. Martín Hechenleitner and Max C. Langer published in Historical Biology.

Visit the Everything Dinosaur website: Dinosaur Toys.

Scientists have named a new species of armoured dinosaur based on cranial and postcranial fossils collected in 2008 from the famous Nemegt Formation of the Gobi Desert, Mongolia. A detailed analysis of the fossil material consisting of a well-preserved skull, vertebrae, ribs, part of the hip and a tail club has been published in the journal “Scientific Reports”. The new ankylosaur has been named Tarchia tumanovae and it is the third species to be assigned to the Tarchia genus.

Location map (a) of the fossil discovery in Mongolia with (b) a larger scale map showing the fossil quarry. Photograph (c) shows the specimen (MPC-D 100/1353) partially excavated with (d) a line drawing of the fossils in situ. T. tumanovae illustrations show known fossil bones in white (e) dorsal view, (f) left lateral view and (g) shows a skeletal reconstruction with dermal armour. Picture credit: Park et al.

Picture credit: Park et al

Evidence of Injury and a Damaged Tail Club

A joint Korean/Mongolian expedition discovered the fossil material at Hermiin Tsav in the southern Gobi Desert. The ribs show signs of fracture healing and there are localised injuries on the pelvic bones. The researchers speculate that these injuries were probably caused by intraspecific combat. The pathology is consistent with tail club strikes. Intriguingly, the tail club of the skeleton also shows signs of injury. The tail club is asymmetrical when viewed from above (dorsal view). A badly healed ossified tendon on the tail knob handle is present, a possible injury caused as the tail was used during combat. Whether this injury occurred as a result of intraspecific combat or when deterring an attack from a theropod is unknown.

Noting a Change in the Diet of Late Cretaceous Ankylosaurids

The scientists noted wide muzzles are a character of low-level, bulk feeders, whereas those ankylosaurines with narrower muzzles such as T. tumanovae and the coeval, closely related Tarchia teresae were probably selective feeders. The researchers demonstrate that ankylosaurid diets shifted from one of low-level, relatively unfussy bulk feeders during the early Campanian to more selective diets as characterised by a narrower muzzle by the late Campanian/early Maastrichtian.

Photographs (a–d) and line drawings (e–h) of the skull of Tarchia tumanovae sp. nov. (MPC-D 100/1353). Photographs of the skull in (a) left lateral, (b) right lateral, (c) anterior, and (d) occipital views. Line drawings in (e) left lateral, (f) right lateral, (g) anterior, and (h) occipital views.

Picture credit: Park et al

It is not known why ankylosaurids show this trend towards selective feeding, although the researchers speculate that this change could have been a consequence of habitat change as the region gradually became less arid towards the very end of the Cretaceous. The research team also postulate that ankylosaurids evolved more selective browsing habits in response to the presence of bulk-feeding saurolophine hadrosaurids such as Saurolophus angustirostris and Barsboldia sicinskii.

A diagram showing (a) a phylogenetic analysis of Tarchia tumanovae, placed in the context of geological time. Ankylosaurids from this region seem to have changed feeding strategies, (b), evolving narrower muzzles that indicate a switch from low-level bulk feeding to more selective browsing. Ankylosaurid fossils from the geologically older Bayanshiree and Djadokhta Formations which represent arid habitats had broad muzzles, whilst ankylosaurids from the younger and more humid Nemegt Formation have narrower muzzles. Picture credit: Park et al.

Picture credit: Park et al

Honouring a Famous Researcher

The species name honours Tat’yana A. Tumanova of the Russian Academy of Sciences, in recognition of her contribution to the study of Mongolian armoured dinosaurs.

The scientific paper: “A new ankylosaurid from the Upper Cretaceous Nemegt Formation of Mongolia and implications for paleoecology of armoured dinosaurs” by Jin-Young Park, Yuong-Nam Lee, Yoshitsugu Kobayashi, Louis L. Jacobs, Rinchen Barsbold, Hang-Jae Lee, Namsoo Kim, Kyo-Young Song and Michael J. Polcyn published in “Scientific Reports”.

The Everything Dinosaur website: Dinosaur Models: Dinosaur Models.

Scientists writing in the journal “Nature” have announced the discovery of a new species of Late Cretaceous ankylosaur from southernmost Chile. The dinosaur named Stegouros elengassen evolved a large tail weapon, unlike any other tail weapon known in the Dinosauria. Stegouros had a flat, frond-like structure formed by seven pairs of laterally projecting osteoderms. This formidable tail weapon superficially resembles a macuahuitl, a frightening war club used by Aztec warriors.

A life reconstruction of the newly described Gondwana ankylosaur Stegouros elengassen. Picture credit: Mauricio Álvarez.

Picture credit: Mauricio Álvarez

A Combination of Stegosaur and Ankylosaur Anatomical Characteristics

The researchers from the University of Chile (Universidad de Chile) in Santiago report on an articulated, nearly complete fossil specimen representing a single animal that was excavated by a field team in February 2018 from sediments relating to the Dorotea Formation in the province of Ultima Esperanza in southern Chile. Stegouros was very small for an ankylosaur, measuring around two metres in length and weighing approximately 100 kilograms.

It shows ankylosaurian cranial characters, but a largely ancestral postcranial skeleton, with some stegosaur-like characters.

A phylogenetic analysis places Stegouros in the Ankylosauria and the research team postulate that it is closely related to other ankylosaurs known from southern Gondwana such as Kunbarrasaurus from Australia and Antarctopelta, fossils of which were found on James Ross Island off the Antarctic Peninsula.

Field team members jacket the fossilised remains of Stegouros. Picture credit: Universidad de Chile.

Picture credit: Universidad de Chile

The Parankylosauria Clade

The researchers propose the establishment of a new clade of ankylosaurs – the Parankylosauria which consists of basal ankylosaurs that split from the main ankylosaurian lineage during the Middle Jurassic, although the fossil evidence for this is currently lacking with Stegouros, Antarctopelta and Kunbarrasaurus forming part of a ghost lineage of basal ankylosaurs with origins back in the mid-Jurassic.

The posterior of the Stegouros specimen with the armoured tail clearly shown. Picture credit: Universidad de Chile.

A Transitional Ankylosaur

Commenting on the significance of this fossil discovery, lead author of the scientific paper, Sergio Soto, a researcher at the University of Chile stated that the fossilised remains of S. elengassen represent a “Rosetta Stone” for deciphering the fragmentary fossils of other ankylosaurs from southern Gondwana.

He added:

“Stegouros is an evolutionary link between ankylosaurs and other older lineages of armoured dinosaurs. Stegouros has only some of the features normally found in ankylosaurs, particularly the skull, but many others are absent. It also has some traits similar to stegosaurs, inherited from a common ancestor with them, but that other ankylosaurs lost in evolution.”

Picture credit: Universidad de Chile

Stegouros roamed the Chilean Patagonia around 74 million years ago. The genus name translates as “roofed tail”, whilst the species name comes from a mythical armoured monster from the folklore of the indigenous Tehuelche people.

Note

CollectA introduced a 1:6 scale figure of this remarkable dinosaur in 2023.  Safari Ltd also added a Stegouros model to their range in 2024.

The CollectA Deluxe 1:6 scale Stegouros elengassen dinosaur model – due to be available mid 2023.

To view the range of CollectA Deluxe prehistoric animal figures available from Everything Dinosaur: CollectA Deluxe Prehistoric Life Models.

The scientific paper: “Bizarre tail weaponry in a transitional ankylosaur from subantarctic Chile” by Sergio Soto-Acuña, Alexander O. Vargas, Jonatan Kaluza, Marcelo A. Leppe, Joao F. Botelho, José Palma-Liberona, Carolina Simon-Gutstein, Roy A. Fernández, Héctor Ortiz, Verónica Milla, Bárbara Aravena, Leslie M. E. Manríquez, Jhonatan Alarcón-Muñoz, Juan Pablo Pino, Cristine Trevisan, Héctor Mansilla, Luis Felipe Hinojosa, Vicente Muñoz-Walther and David Rubilar-Rogers published in the journal Nature.

The Everything Dinosaur website: Dinosaur Toys and Models,

Known from a single specimen discovered in Spain back in 1993 Pelecanimimus (P. polyodon) from the Las Hoyas lagerstätte was the first unambiguous ornithomimosaur described from Europe. Although the scientific paper erecting the genus was published in 1994, no detailed examination of the holotype fossil material (LH 7777) had been undertaken.

A re-examination of the holotype fossil has been carried out by a team of international scientists, which included Francisco Ortega, one of the authors of the original scientific paper describing this 2-metre-long theropod. They conclude that Pelecanimimus was remarkably bird-like although as a member of the Ornithomimosauria it was not that closely related to the dinosaur lineage that led to the evolution of the birds.

An Ossified Sternum

Pelecanimimus when it was named, was the only ornithomimosaur that had a preserved ossified sternum. The sternum is not usually preserved in theropods, it has been suggested that this part of the skeleton was not ossified and therefore it did not fossilise well, or perhaps the absence of this structure was due to preservational bias. The distance observed between the coracoids in articulated theropod specimens led to many palaeontologists inferring its presence. In this new paper, the researchers examined the shape of the sternum and concluded that its morphology was similar to the sternums of dinosaurs more closely related to birds such as Velociraptor and Oviraptor (the Maniraptora clade).

Pelecanimimus Breathed Like a Bird

Furthermore, the research team found evidence of the presence of uncinate processes. These small, hook-shaped bones are linked to the ribs and are also present in extant and extinct birds. Pelecanimimus is the only known representative of the Ornithomimosauria with these structures and this is the first time that uncinate processes have been found in a non-maniraptoran theropod. If maniraptorans evolved these structures, along with the distantly related Pelecanimimus, this suggests convergent evolution.

In birds, uncinate processes function to increase the mechanical advantage for movements of the ribs and sternum during respiration. They make breathing more efficient. In summary, the research team suggest Pelecanimimus, breathed like a modern bird.

Elena Cuesta, the lead author of the study from the Fukui Prefectural University, Japan explained:

“The fact that Pelecanimimus preserved these processes suggests that it also had a bird-like breathing mechanism. Apparently, the origin of such avian-like features is older and more widespread than thought. However, the evolutionary history of both the ossified sternum and uncinate processes is still unclear. Nevertheless, their detection in Pelecanimimus confirms that these elements were present in Ornithomimosauria as well as in other dinosaurs.”

Distinctive Features on the Hands

The joint Japanese/Spanish research team also discovered distinctive features on the hands. The manus of Pelecanimimus has conspicuously elongated metacarpals, particularly metacarpal I and lengthened distal phalanges, a feature also found in some later, more derived ornithomimosaur species. The authors of the study conclude that these anatomical features require the erection of a new clade, the Macrocheiriformes. This clade is defined as including Pelecanimimus and more derived ornithomimosaurs. The term Macrocheiriformes, means “forms with large hands.”

The scientific paper: “Pelecanimimus (Theropoda: Ornithomimosauria) postcranial anatomy and the evolution of the specialized manus in Ornithomimosaurs and sternum in maniraptoriforms” by Elena Cuesta, Daniel Vidal, Francisco Ortega, Masateru Shibata and José L Sanz published in the Zoological Journal of the Linnean Society.

A new dinosaur from Appalachia – Parrosaurus missouriensis.

For much of the Cretaceous the North American landmass was effectively divided into two, by a shallow sea (Western Interior Seaway). At its greatest extent it was around 1,000 kilometres (600 miles) wide, the long, narrow landmass that represented the western part of North America is known as Laramidia and palaeontologists have amassed a huge amount of data about the abundant dinosaurs that roamed these ancient shores. The eastern landmass, Appalachia, stretched from Newfoundland in the north, to the mid-west American states, but in comparison little is known about the Appalachian dinosaur fauna.

A new species of duck-billed dinosaur has been added to the Appalachian biota, named Parrosaurus missouriensis and as the species epithet suggests, this Late Cretaceous herbivore was found in Missouri.

Very Rare Dinosaur Discovery

In contrast to the extensive, rapidly eroding “Badlands” of Montana, Wyoming and North/South Dakota, rocks of Cretaceous age from the ancient landmass of Appalachia are not exposed to any great extent in eastern North America. Dinosaur fossil bearing units are not being eroded, they remain buried under other strata and to add to this dilemma, much of the eastern part of the USA is conurbation. However, there are bright spots for palaeontologists looking for dinosaur bones.

Mines, eroding rivers and construction sites can all provide opportunities for fossil discoveries. Indeed, it was the digging of a well near to the village of Glen Allen in Bollinger County, south-eastern Missouri back in 1942 that led to the finding of several dinosaur bones, the first time such fossils had been reported from the “Show Me State”.

The caudal vertebrae that were excavated from the site were thought to represent a sauropod and it was scientifically described and named Neosaurus missouriensis in 1945 (Gilmore and Stewart). It was noted that the genus name was already occupied, Neosaurus having been erected in 1869 for a Palaeozoic synapsid from France, so the scientific name was changed to Parrosaurus missouriensis.

Duck-billed Dinosaur Fossils

Ironically, duck-billed dinosaur fossils had been found in North Carolina and the species Hypsibema crassicauda was erected in 1869, a review of the Glen Allen material (Baird and Horner), led to the erection of the species Hypsibema missouriensis as the Missouri fossils were confirmed to be hadrosaurid and showed similarities with the fossils that had been found in North Carolina.

More recent excavations carried out at the Glen Allen site, led by fossil expert Guy Darrough and with the support of the Field Museum of Chicago has led to the discovery of at least four individual hadrosaur specimens. The fossils found in close association in black clay represent three adults and juvenile.

The site has yielded other fascinating fossils, providing a glimpse into the fauna of Appalachia. For example, a scute (dermal armour) from a giant crocodilian has been found, fossils of turtles discovered and even the tooth of a tyrannosaur has been uncovered.

Parrosaurus missouriensis

The extensive fossil material found as led to the establishment of a new species Parrosaurus missouriensis. This very notable fossil location might just prove to be a headache for the State administration, as in 2004 these fossils had been declared Missouri’s official State dinosaur when they were assigned to Hypsibema missouriensis.

The story has been widely reported and team members at Everything Dinosaur are optimistic that once the fossil material has been studied in detail and more of the specimens cleaned and prepared, then new discoveries will be made.

This month has seen another new species of sauropodomorph named and described. Issi saaneq (pronounced is-y sa-ah-neq), roamed what is now eastern Greenland around 214 million years ago (Late Triassic), this new dinosaur has been named based on two fossil skulls believed to represent one juvenile and one older animal possibly a sub-adult. Ascribed to the Plateosauridae family and showing affinities to South American sauropodomorphs I. saaneq helps to extend our understanding of the evolution and development of these important early dinosaurs.

Originally Assigned to Plateosaurus

The skull fossils were found in the early 1990s, during excavations of sediments representing lake shore deposits that make up part of the of the Malmros Klint Formation in Jameson Land, Greenland. The larger skull was found in 1991, the smaller skull, now believed to represent the same species was found subsequently along with numerous other fossils including skull material that has yet to be catalogued and described.

The two skulls (specimen numbers NHMD 164741 and NHMD 164758), are now part of the vertebrate fossil collection of the Natural History Museum of Denmark. Postcranial material was also found in association with the smaller skull (NHMD 164758) and this could have come from the same animal, but these bones have also not yet been examined in detail.

When first found, it was thought that these fossils were examples of Plateosaurus (P. engelhardt which is now regarded as nomen dubium with fossil material assigned to P. trossingensis). As several new sauropodomorphs had been described in recent years, the researchers were able to tap into the wealth of new fossil data and confidently assign the skulls to a new genus.

Commenting on the significance of the find, lead author of the scientific paper, published in the journal “Diversity”, Doctor Victor Beccari (Universidade Nova de Lisboa), stated:

“The anatomy of the two skulls is unique in many respects, for example in the shape and proportions of the bones. These specimens certainly belong to a new species.”

“Cold Bone” – Issi saaneq

Issi saaneq is the first non-avian dinosaur to be named from fossils found in Greenland. The name comes from the local Inuit language, with “issi” meaning cold and “saaneq” meaning bone. This is a reference to the harsh and very unpleasant weather conditions associated with the fossil site. The bones of this dinosaur were cold to the touch and the field team were often “frozen to the bone” as they worked in the extremely chilly conditions.

Affinities with South American Sauropodomorphs as well as Plateosaurus

Phylogenetic assessment indicates that Issi saaneq has affinities to Brazilian plateosaurids such as Macrocollum (M. itaquii) and the European Plateosaurus, being recovered as the sister clade of Plateosaurus in this study. It is the northernmost record of a Late Triassic sauropodomorph.

To read Everything Dinosaur’s blog post about the naming and scientific description of Macrocollum itaquii: How Did Some Dinosaurs Get Long Necks?

The discovery of Issi saaneq expands the known geographical range of these dinosaurs and broadens our knowledge about the evolution of the Sauropodomorpha.

The scientific paper: “A New Sauropodomorph Dinosaur from the Late Triassic (Norian) of Jameson Land, Central East Greenland” by Victor Beccari, Octávio Mateus, Oliver Wings, Jesper Milàn and Lars B. Clemmensen published in Diversity.