The discovery of a titanosaurid egg, preserved inside another titanosaur egg (ovum-in-ovo) adds weight to the theory that dinosaurs had a reproduction strategy very similar to birds. This discovery opens up the possibility that dinosaurs laid their eggs sequentially like birds, whereas other reptiles tend to lay eggs simultaneously as a clutch.

The researchers from the University of Delhi in collaboration with a colleague from the Higher Secondary School (Dhar District, Madhya Pradesh), documented the contents of a titanosaur nest discovered in Upper Cretaceous deposits (Maastrichtian stage) from the Lameta Formation exposed in the lower Narmada valley. The Lameta Formation is famous for its titanosaur nest fossils, hundreds of individual nests have been recorded. The titanosaur nest which records a rare example of an abnormal egg is known as P7, it is one of fifty-two titanosaur nests that have been mapped around the village of Padlya.

In-situ field photograph and explanatory drawing of the outcrop showing the titanosaur nest P7 and its eggs and eggshell fragments. Captions A to O indicate eggs and eggshell locations. Picture credit: Dhiman et al.

Picture credit: Dhiman et al

Titanosaur Nest P7

The titanosaur nest P7 preserves eleven large, round eggs which are placed in a circular arrangement entombed within a block of sandy limestone. Not all the eggs are entire, some of the eggshell is missing. They could represent broken shells after the eggs hatched or the missing shell elements may have been eroded away.

One egg (egg C) records unusual pathology. Two partially broken, circular eggshell outlines are preserved, with a prominent crescent-shaped gap between the two eggshells present in the top right corner (see line drawing). Egg C has been interpreted as an example of an abnormal egg, one egg containing another egg within it. This type of egg pathology is termed ovum-in-ovo and this is the first time this has been reported in a dinosaur. Ovum-in-ovo eggs are found in birds but no such egg pathology has been reported in a reptile (living or extinct). This discovery suggests that titanosaurids had a reproductive system similar to that of birds.

In-situ field photograph (a) of the ovum-in-ovo egg (egg number C) from the Upper Cretaceous Lameta Formation (Dhar District, India) with explanatory line drawing (b). Two partially broken, circular eggshell outlines can be seen with broken eggshell fragments also preserved. With ovum-in-ovo egg pathology a crescent-shaped gap is characteristically present in the upper right part of the egg. Picture credit: Dhiman et al

Picture credit: Dhiman et al

Different Types of Egg Pathology

Abnormal egg formation has been documented in many types of amniote (undergoing foetal or embryonic development within a protective membrane, the amnion), such as turtles, dinosaurs and birds. Two main examples of egg pathology are known. There is a condition where one egg forms within another egg (ovum-in-ovo) and a second condition in which multi-shelled eggs are formed, essentially the formation of a second eggshell layer beside the primary eggshell.

Unusual pathologies in amniote eggs. Ovum-in-ovo (a) an egg within an egg, characterised by the presence of two yolks. Multi-shelled egg (b) with two or more eggshell layers surrounding a single yolk. Picture credit: Dhiman et al (after Carpenter).

Picture credit: Dhiman et al (after Carpenter)

If Egg C represents an example of ovum-in-ovo egg laying in a dinosaur, then this egg deformity will only have been recorded in the Dinosauria and birds, suggesting similar reproductive biology. In birds, when an egg is fully formed it is pushed into the cloaca to be laid one-by-one.

Eggs are not laid as clutch, but egg laying can take place sequentially over several days. In birds such as hens (Galliformes), egg laying can be suspended if conditions are unfavourable. However, crocodiles and turtles tend to lay all their eggs at the same time, as a single clutch. Both turtles and crocodiles have two oviducts, but crocodiles are more derived than turtles possessing a segmented oviduct and share this derived trait with the birds.

The structure of the oviduct dictates the sort of egg abnormalities that can occur. The ovum-in-ovo pathology as observed in the titanosaur eggs has led the researchers to hypothesise that titanosaurs possessed a segmented oviduct similar to birds and crocodiles, but unlike crocodilians they were capable of laying eggs sequentially.

Inferred cladogram showing divergence of dinosaurs from crocodiles on the basis of sequential egg laying. Picture credit: Dhiman et al.

Picture credit: Dhiman et al.

Building up a Picture of Titanosaurid Reproductive Strategy

Turtles, crocodiles, dinosaurs and birds all share the common trait of having multi-shelled eggs. Both turtles and crocodiles have two oviducts, but crocodiles are more derived than turtles in that they possess a segmented oviduct, a characteristic that they share with birds.

This new study suggests that at least one type of dinosaur (titanosaurids) had an oviduct anatomy and biology similar to modern birds. Titanosaurs may have been capable of laying eggs sequentially, just like birds.

Palaeontologists are building up a detailed picture of titanosaur reproductive behaviour. These sauropods had favoured nesting sites, which they returned to, they nested in colonies, excavated nests and covered the nests to incubate the eggs and they may have laid their eggs not as a single clutch but sequentially over several days.

The titanosaur egg fossils were found in two distinct layers (L1 and L2) approximately two metres apart. This suggests that this area was a preferred nesting site for titanosaurs. This is the first confirmed dinosaur nesting area found in Brazil. The eggs attributed to titanosaurs also represent the most northerly titanosaurian nesting site known from South America. The discovery of nests located at different levels indicates that titanosaurs returned regularly to preferred nesting areas. Picture credit: Fiorelli et al.

Picture credit: Fiorelli et al

Safari Ltd recently introduced a model of a titanosaur (Patagotitan). To view this figure and the other models in the Wild Safari Prehistoric World range: Wild Safari Prehistoric World.

The scientific report: “First ovum-in-ovo pathological titanosaurid egg throws light on the reproductive biology of sauropod dinosaurs” by Harsha Dhiman, Vishal Verma & Guntupalli V. R. Prasad published in Scientific Reports.

The award-winning Everything Dinosaur website: Dinosaur Figures.

Last week, the discovery of the fossilised bones of a huge spinosaurid from the Isle of Wight was reported*. This giant theropod, with an estimated length of around ten metres, could be the biggest meat-eating dinosaur described from European fossils, but the largest theropod known to science is thought to be Spinosaurus aegyptiacus, which was first reported from the Bahariya Formation of Egypt.

Spinosaurus had plenty of company, several large theropods have been named and described from fossils from the Upper Cretaceous (Cenomanian), Bahariya Oasis, Western Desert of Egypt and a newly published paper confirms the presence of abelisaurids in this ancient ecosystem too.

Reconstruction of the palaeoecosystem of the Upper Cretaceous (Cenomanian) Bahariya Formation of the Bahariya Oasis, Western Desert of Egypt. A single neck bone proves the presence of abelisaurids in the ecosystem. Picture credit: Andrew McAfee, Carnegie Museum of Natural History.

Picture credit: Andrew McAfee, Carnegie Museum of Natural History

Cervical Vertebra Fossil Discovery

A 2016 expedition led by researchers from the Mansoura University Vertebrate Palaeontology Centre, (Mansoura, Egypt), unearthed a single neck bone (10th cervical vertebra), a formal description of this specimen (MUVP 477) has been published in Royal Society Open Science.

Tenth cervical vertebra of Abelisauridae indet. (MUVP 477) in cranial (a), caudal (b), left lateral (c), right dorsolateral (d), ventral (e) and dorsal (f) views. Note scale bar = 5 cm. Picture credit: Salem et al.

Picture credit: Salem et al

Similar to the Cervical Vertebrae of Majungasaurus and Carnotaurus (Abelisaurids)

The neckbone is strikingly similar to the cervical vertebrae of Majungasaurus from the Late Cretaceous of Madagascar and the cervical vertebrae of Carnotaurus, fossils of which are associated with Upper Cretaceous deposits of Argentina. Phylogenetic analysis places the Bahariya Formation specimen within the Abelisauridae, but the absence of any further fossil material has restricted the taxonomic classification to the family level (a similar taxonomic position to that of the “White Rock spinosaurid” described from fragmentary bones found on the Isle of Wight).

Based on measurements of the cervical vertebra the Bahariya Formation abelisaurid is estimated to have had a body length of between 5.3 and 6.3 metres, indicating that this fossil represents a mid-sized member of the Abelisauridae with a body size similar to Rugops, Majungasaurus, Viavenator and Xenotarsosaurus bonapartei.

Abelisaurid size comparison. The Bahariya Formation abelisaurid is described as mid-sized member of the Abelisauridae with a body length estimated to be 5.3 to 6.3 metres long. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The First Definitive Proof of Abelisaurids and the Oldest from North-eastern Africa

Specimen number MUVP 477 is not only the first definitive proof of the presence of abelisaurids with the Bahariya Formation biota, but with an estimated age of approximately 98 million years, this fossil is also the oldest record of the Abelisauria clade in Egypt and north-eastern Africa generally.

Providing a Key for the Carnegie Museum of Natural History Life Reconstruction

Reconstruction of the palaeoecosystem of the Upper Cretaceous (Cenomanian) Bahariya Formation of the Bahariya Oasis, Western Desert of Egypt. The early Late Cretaceous of north-eastern Africa was a dangerous place with several different types of predatory dinosaur present in the ecosystem. Picture credit: Andrew McAfee, Carnegie Museum of Natural History.

Picture credit: Andrew McAfee, Carnegie Museum of Natural History

The stunning prehistoric scene (Andrew McAfee/Carnegie Museum of Natural History) shows, the mid-sized abelisaurid (far right) confronting the giant theropod Spinosaurus aegyptiacus which is holding a dipnoan (lungfish) Retodus tuberculatus in its jaws.

The large carcharodontosaurid Carcharodontosaurus saharicus can be seen in the centre background. Two stomatosuchid crocodyliforms (Stomatosuchus inermis) can be seen on the far left, whilst in the background a trio of Paralititan stromeri walk by. A pair of bahariasaurids are located just behind the tail of the abelisaurid whilst a flock of pterosaurs soar overhead. The vegetation is dominated by the mangrove-like tree fern Weichselia reticulata.

Niche Partitioning

The presence of so many large predators in the biota suggests that the Bahariya Formation ecosystem was extremely rich, even so, it is likely that the different types of theropod exhibited niche-partitioning, with coeval genera exploiting different resources.

*To read our article on the “White Rock spinosaurid”: Super-sized Carnivorous Dinosaur from the Isle of Wight.

The scientific paper: “First definitive record of Abelisauridae (Theropoda: Ceratosauria) from the Cretaceous Bahariya Formation, Bahariya Oasis, Western Desert of Egypt” by Belal S. Salem, Matthew C. Lamanna, Patrick M. O’Connor, Gamal M. El-Qot, Fatma Shaker, Wael A. Thabet, Sanaa El-Sayed and Hesham M. Sallam published by Royal Society Open Science.

The award-winning Everything Dinosaur website: Dinosaur Models and Toys.

Scientists have identified two partial pterosaur thigh bones that despite one being at least ten million years older than the other, have been identified as belonging to the same type of flying reptile (Anhangueria). Furthermore, one of the bones preserves a potential bite mark tentatively attributed to a crocodilian.

Anhangueria indet. partial right femur from the Toolebuc Formation (NMV P231549): A, B, proximal; C, D, posterior; E, F, dorsal; G, H, anterior; I, J, ventral and K, distal views. A, C, E, G, I and K are photographs; B, D, F, H and J are 3D renders derived from surface scan data. Scale bar = 2 cm. Picture credit: Pentland et al.

Picture credit: Pentland et al

Two Rare Australian Pterosaur Fossils

The researchers who include famous Australian vertebrate palaeontologists Patricia Vickers-Rich and Thomas Rich report that the two bones although found over 200 miles apart, both come from pterosaurs from the same pterosaur clade (Anhangueria).

Specimen number NMV P231549 was collected in 1991 at Slashers Creek Station, southeast of the small town of Boulia (Queensland), from Toolebuc Formation deposits (middle to upper Albian) and is believed to be at least 100 million years old.

Specimen number AODF 2297 was found in 2004 at Belmont Station, around 35 miles northeast of the town of Winton in Queensland. It came from deposits associated with the “upper” Winton Formation (Cenomanian-lowermost Turonian stage of the Late Cretaceous). It is estimated to be around 10 million years younger.

Anhangueria indet. partial left femur from the Winton Formation (AODF 2297): A, B, posterior; C, D, dorsal; E, F, anterior; and G, H, ventral views. A, C, E and G are photographs; B, D, F and H are 3D renders derived from surface scan data. Scale bar = 2 cm. Picture credit: Pentland et al.

Picture credit: Pentland et al

Although pterosaur fossils are exceptionally rare in Australia and most specimens are extremely fragmentary, their three-dimensional preservation has enabled palaeontologists to learn a great deal about the type of pterosaurs that ranged over this part of Gondwana during the Cretaceous.

Lead author of the scientific paper describing these pterosaur bones, Adele Pentland (PhD student at Swinburne University, Melbourne, Victoria), was also the lead author of another scientific paper published in 2019 which described another anhanguerid pterosaur Ferrodraco lentoni.

To read more about F. lentoni: The Most Complete Pterosaur Specimen Found in Australia to Date.

A pair of Mojo Fun Tropeognathus pterosaurs.

The picture (above) shows two Tropeognathus pterosaurs, soaring high in the sky.  These pterosaurs are typical of the Anhangueridae. The models are from the Mojo Fun series.

To view the range of Mojo Fun figures available from Everything Dinosaur: Mojo Fun Prehistoric Animal Figures.

The Winton Formation fossil preserves a potential bite mark, that the researchers have tentatively proposed was made by a crocodylomorph. It is not known whether this feeding trace represents predation or post-mortem scavenging.

Comparisons between greater trochanters of the Toolebuc Formation (NMV P231549) and Winton Formation (AODF 2297) pterosaur femora. AODF 2297 in A, B, dorsal view. NMV P231549 in C, D, dorsal view. A and C are photographs; B and D are 3D renders derived from surface scan data. Picture credit: Pentland et al.

Picture credit: Pentland et al

The scientists conclude that these new pterosaur fossils are a valuable addition to the meagre list of pterosaur specimens found in Australia and attest to the cosmopolitan distribution of anhanguerians during the Early and early Late Cretaceous.

The scientific paper: “New anhanguerian pterosaur remains from the Lower Cretaceous of Queensland, Australia” by Adele H. Pentland, Stephen F. Poropat, Matt A. White, Samantha L. Rigby, Patricia Vickers-Rich, Thomas H. Rich and David A. Elliott published in Alcheringa: An Australian Journal of Palaeontology.

A new species of short-snouted troodontid has been named and described based on fossils found in the Upper Cretaceous Wulansuhai Formation at Bayan Manduhu, Inner Mongolia. This little dinosaur has been named Papiliovenator neimengguensis.

Everything Dinosaur team members have been busy updating readers about new dinosaurs named and described this year (see below*), the formal scientific paper announcing this new troodontid was published earlier in the spring, but information about the fossils attributed as the holotype material had been circulating for some time.

Named From Strangely Shaped Dorsal Vertebrae

Known from a nearly complete skull and fragmentary, semi-articulated postcranial material thought to represent a single, individual animal, Papiliovenator means “butterfly hunter”. This little carnivore, which was less than a metre long, might well have hunted butterflies and other members of the Lepidoptera, but the derivation of the genus name does not reflect this dinosaur’s diet. Instead, it was the unusual shape of the neural arches associated with the two dorsal vertebrae closest to the neck of this dinosaur that inspired the genus name. When viewed from above (dorsal view), these neural arches are butterfly-shaped.

Unusual for a Late Cretaceous Troodontid

The researchers report that Papiliovenator was unusual among Late Cretaceous troodontids in having a fairly deep, short-snouted skull. This skull shape is seen in geologically older troodontids known from the Early Cretaceous. Most other Late Cretaceous troodontids have long, low snouts, except for the smaller Almas ukhaa from the Campanian-aged Djadochta Formation of Mongolia. Coincidently, Rui Pei of the Chinese Academy of Sciences was the lead author of the scientific paper naming and describing A. ukhaa (Pei et al, 2017). Rui Pei is the lead author of the paper describing Papiliovenator.

*To read about a new basal iguanodontian from southern China: Napaisaurus guangxiensis.

*A new alvarezsaurid taxon from Uzbekistan: Dzharaonyx eski Old Dzharakuduk Claw.

*A new therizinosaur from the Japanese island of Hokkaido: Paralitherizinosaurus japonicus.

The fossils are thought to represent a sub-adult animal. The discovery of Papiliovenator neimengguensis allows for an improved understanding of troodontid anatomy, as well as helping to highlight the regional variation of troodontids from the Upper Cretaceous of the Gobi Basin.

The scientific paper: “A new troodontid from the Upper Cretaceous Gobi Basin of inner Mongolia, China” by Rui Pei, Yuying Qin, Aishu Wen, Qi Zhao, Zhe Wang, Zhanmin Liu, Weilesi Guo, Po Liu, Weiming Ye, Lanyun Wang, Zhigang Yin, Ruiming Dai and Xing Xu published in Cretaceous Research.

Visit the Everything Dinosaur website: Everything Dinosaur.

Researchers have named the largest pterosaur found to date in South America. The giant Thanatosdrakon (T. amaru) is estimated to have had a wingspan of around nine metres and it would have stood as tall as a giraffe.

Writing in the academic journal “Cretaceous Research”, the scientists, have assigned Thanatosdrakon to the Azhdarchidae family of pterosaurs and postulate that it was closely related to the slightly larger and geologically younger Quetzalcoatlus, fossils of which are known from North America.

The paratype fossil a giant left humerus (UNCUYO-LD 350) is carefully cleaned at the dig site. Picture credit: Reuters/ICB-CONICET/UNCUYO.

Picture credit: Reuters/ICB-CONICET/UNCUYO

One of the Largest Flying Vertebrates Known

The fossil material, thought to represent two individual pterosaurs was found in the upper-most levels of the Plottier Formation (upper Coniacian–lower Santonian, Neuquén Basin), Mendoza, western Argentina. The researchers, who include CONICET* researcher Dr Leonardo Ortiz David, Dr Bernardo González Riga, director of the Laboratory and Museum of Dinosaurs of the Faculty of Exact and Natural Sciences and world-renowned pterosaur expert Dr Alexander Kellner (Director of the National Museum of Rio de Janeiro, Brazil), estimate that Thanatosdrakon lived around 86 million years ago. Based on the single, huge left humerus of the paratype (UNCUYO-LD 350), a wingspan of around 9 metres is proposed, making Thanatosdrakon amaru one of the largest flying vertebrates known to science.

Comparing the estimated wingspans of the paratype and holotype fossil material associated with Thanatosdrakon amaru with large, extant birds. Picture credit: ICB-CONICET/UNCUYO.

Picture credit: Reuters/ICB-CONICET/UNCUYO

Exceptionally Preserved Fossils

A civil construction project had uncovered some of the fossils. A field team was despatched to map the site and to recover the exceptionally well-preserved bones. The fossil material consists of vertebrae and bones from the limbs. As the larger humerus was found in close proximity to the other fossils, the scientists have speculated that this huge animal was social and probably lived in flocks.

Thanatosdrakon is the oldest taxon of the clade Quetzalcoatlinae so far described. As the strata containing the fossil bones represent deposition in a floodplain environment with ephemeral meandering streams and rivers, the researchers conclude that like the much later Quetzalcoatlus, Thanatosdrakon inhabited continental, inland areas.

Skeletal reconstructions of Thanatosdrakon amaru. The holotype fossil material (UNCUYO-LD 307) and the left humerus paratype (UNCUYO-LD 350). Picture credit: ICB-CONICET/UNCUYO.

Picture credit: Reuters/ICB-CONICET/UNCUYO

Important Information on Azhdarchid Anatomy

The fossils are not distorted or flattened to any great degree. Their three-dimensional preservation will help the researchers to learn more about the anatomy of giant pterosaurs. In addition, some of the fossil bones such as the dorsosacral vertebrae and caudal vertebra along with the notarium (the structure formed by fusion of the dorsal vertebrae, seen in pterosaurs and birds), have never been described in giant azhdarchids. The researchers expect that further study of these bones will provide important information on azhdarchid anatomy.  Hopefully, new fossil finds will provide more information on the Azhdarchidae.

The “Dragon of Death”

This large pterosaur probably hunted on the ground, perhaps stalking prey in a similar manner to the marabou stork (Leptoptilos crumenifer) which is found in sub-Saharan Africa. The genus name is derived from the Greek words thanatos which means death and drakon (dragon). The species name honours the Inca winged serpent (Amaru).

CONICET* (Consejo Nacional de Investigaciones Científicas y Técnicas [National Council for Scientific and Technical Research of Argentina]).

The scientific paper: “Thanatosdrakon amaru, gen. et sp. nov., a giant azhdarchid pterosaur from the Upper Cretaceous of Argentina” by Leonardo D. Ortiz David, Bernardo J. González Riga and Alexander W. A. Kellner published in the journal Cretaceous Research.