Ikrandraco avatar – New Species of Cretaceous Pterosaur Described

An international team of palaeontologists have described a new species of flying reptile that lived in what is now China during the Cretaceous period, about 120 millions years ago, and named it after the flying dragon-like creatures from the 2009 movie blockbuster directed by James Cameron – Avatar.  The fossils, which have both been laterally compressed, were found at two separate sites, around fifteen miles apart, although one is smaller than the other, they have both been assigned to a single new species – Ikrandraco avatar, the name translates as “Ikran dragon from Avatar”.

Ikrandraco avatar

One of the Newly Described Pterosaur Fossils

White scale bar = 5cm.

Picture credit: Scientific Reports/Xiaolin Wang et al

Both fossils come from the Jiufotang Formation of north-eastern China (Liaoning Province), although the exact stratigraphic location for both specimens has been difficult to determine.  The larger of the two specimens indicates a wingspan in excess of 2.4 metres, making this flying reptile slightly larger than a Golden Eagle.  The lower jaw had a distinct, semi-circular crest on its anterior portion, it has been suggested that a large “hook” at the back of this structure helped to support either an enlarged throat or a pouch, broadly similar to that seen in extant Pelicans.

A Joint Chinese and Brazilian Research Team

The joint Chinese and Brazilian research team that studied the fossil material and published the scientific paper on the new discoveries, propose that this pterosaur probably fed on small fish.  It may have flown over the water catching prey by skimming its lower jaw into the water.  Once the jaw connected with a fish, it snapped shut and the fish was stored in the throat pouch prior to swallowing.

This type of feeding, a skimming over the water surface to collect fish approach has been proposed before for members of the pterosaur family.  To read an article written by Everything Dinosaur team members back in 2007, click on the link here: Pterosaur Feeding Habits – Could they Skim Surface Waters for Fish?

New Pterosaur Species

Dr Alexander Kellner of the Federal Univervisty (Rio de Janeiro, Brazil), one of the senior authors of the academic paper and an authority on Cretaceous pterosaurs commented:

“Ikrandraco didn’t have a crest on the top of its elongated head as many pterosaurs did.  Behind the lower jaw crest was a hook-like structure that appears to have been the anchor point for the throat pouch.”

The Jiufotang Formation is a member of the extensive Jehol Group and scientists have been able to build up an detailed picture of the environment that existed in this part of the world in the Early Cretaceous.  Although the exact age of the Jiufotang Formation is still debated, most observers now believe that the majority of the strata was laid down in the Early Cretaceous (Aptian faunal stage).

Early Cretaceous Pterosaur

A spokesperson from Everything Dinosaur stated:

“It is now thought that the highly fossiliferous rocks of this part of the world were laid down around 120 million years ago.”

Ikrandraco avatar exhibits a number of anatomical characteristics that suggest it was a piscivore.  For example, the teeth in the jaw are small, sharp and pointed, ideal for grabbing and holding slippery fish.  The unusual blade-like crest on the lower jaw reminded the scientists of the crests seen on the dragon like creatures in the 2009 movie Avatar.

Most flying reptile fossils have been found in marine strata.  However, over the last twenty years or so an increasing amount of pterosaur fossil material has been found in rocks that were laid down inland.  A number of different pterosaur types co-existed in this part of China around 120 million years ago, intriguingly, these reptiles shared the air with a large number of primitive, enantiornithine birds.

A Tropical Paradise

The habitat was a tropical paradise, with verdant forests and a great many, large bodies of freshwater that teemed with fish.  Fossils found in this region include feathered dinosaurs (saurischian as well as ornithischian), early mammals, frogs, turtles, fish and birds.

Commenting on the habitat, Dr Xiaolin Wang of the Chinese Academy of Sciences, a co-author of the scientific paper stated:

“It [Ikrandraco] lived in a warm region teeming with life that included feathered dinosaurs, birds, mammals and frogs along with a variety of trees and other plants.”

An Artist’s Impression of Ikrandraco avatar (Early Cretaceous of North-eastern China)

A flock of Ikrandraco Pterosaurs “fishing”.

Picture credit: Chuang Zhao

Examining Skull and Jaw Crests in the Pterosauria

Of the 130 or so genera of pterosaur described to date, a  number of them are known to have had skull or jaw crests.  These crests were either made of bone or formed by a combination of bone and soft tissue.  However, Ikrandraco avatar is unique in that it only had a crest on its lower jaw (mandible).  There is no evidence of a crest on the skull or upper jaw.  Up until now, blade-like crests were known exclusively in the Anhangueria family and in Cimoliopterus cuvier with such crests also noted in Ludodactylus sibbicki (although the evidence of a blade-like crest in this species is debated).

The researchers also note that Cearadactylus atrox (an ornithocheirid from Brazil), also possessed a crest, but only on the front portion of the upper jaw (the premaxilla).  The crest configuration of a crest on the skull but none on the mandible is much more common in the Pterosauria.  In essence, skull crests are far more common than crests on the jaws and a single, lower jaw crest in a species was unheard of until Ikrandraco came along.

The Second Specimen of Ikrandraco avatar

Scale bar = 5cm.

Picture credit: Scientific Reports/Xiaolin Wang et al

The photograph and line drawing above shows the second referred specimen of I. avatar.  The crest on the lower jaw with its distinctive “hook” at the back (labelled dcr – dentary crest) can clearly be made out.

Closely Related Species

As the specimens were found around fifteen miles apart, it could be that these two fossils represent different, but closely related species.  However, the researchers discounted this as both specimens were preserved in a left lateral view and although flattened, the team did not record any observable anatomical differences.  Both specimens revealed evidence of a unique, hook-like structure at the back of the blade-like crest.  This could have served as an anchor point for soft tissues that made up either an extended throat or a pouch.

The presence of throat sacs (pouches) in pterosaurs has been proposed on numerous occasions.  The suggestions have been made for Late Jurassic species from the famous Solnhofen deposits of southern Germany.  It has been suggested that both Rhamphorhynchus and Pterodactylus had pouches.  In all previously described cases, the pouch starts at the posterior ventral part of the mandible and extends until the level of the third or fourth neck bones (cervical vertebrae).

A Pouch Like a Pelican?

Due to the difficulties of preservation of such structures, their properties, size and shape are disputed.

Some palaeontologists have proposed that these pouches were similar to those seen in extant Pelicans, others have used the more neutral term of “loose extensible skin”.  These protagonists argue that this gullet structure might have helped them swallow larger prey items whole, as seen in modern day Ostriches, for example.

It is interesting to note that the inspiration for the scientific name came from the movie Avatar. Next year sees the release of Jurassic World, the fourth movie in the extremely successful Jurassic Park franchise.  Although a closely guarded secret, the film is very likely to include a super-sized, apex predator with a large number of teeth.  We at Everything Dinosaur confidently predict that whatever the film makers come up with, it will one day be the inspiration behind the naming of another prehistoric animal that is new to science.

For scale models of pterosaurs and other Early Cretaceous prehistoric animals: CollectA Deluxe Pterosaur and Prehistoric Animal Models.

Scientists Explore the Miniature Ecosystem Created by an Ichthyosaur Carcase

It has been known for some time that when cetaceans (whales and dolphins) die and their corpses settle on the seabed, the carcase can sustain a diverse ecosystem for many years, even decades with the largest individuals.  Palaeontologists had long suspected that the corpses of marine reptiles that patrolled the seas of the world long before the whales evolved, would have played a similar role, but until now this area of marine reptile research had not been that thoroughly investigated.

Studying Decay

Stepping up to this challenge, scientists from the Natural History Museum (London) and the Centre for Research in Earth Sciences (Plymouth University) set about mapping the evidence preserved on the fossilised bones and surrounding matrix of an ichthyosaur skeleton found in southern England.

The team concluded that although there was evidence for a succession of community feeding phases, phases which are very similar to those found in association with cetacean remains deposited in shallow water, the fossilised communities differed from those associated with whale carcases deposited in deep water environments.  One phase, consisting of the establishment of a community feeding on inorganic compounds such as methane and sulphides (known as the “sulphophilic phase”) seemed to be absent according to this fossil study.

Exploring the “After Life” of an Ichthyosaur

Ichthyosaurus model (Carnegie Collectibles).

Picture credit: Everything Dinosaur/Safari Ltd

Ichthyosaur

Ichthyosaurs were a very diverse group of marine reptiles that evolved in the Early Triassic and survived up until the Late Cretaceous (Olenikian faunal stage of the Early Triassic to Turonian faunal stage of the Late Cretaceous).  Although, ichthyosaurs had the same basic, streamlined body plan, a number of families are now recognised and these reptiles, only distantly related to the Dinosauria are regarded by many palaeontologists as amongst the best adapted of all the reptiles to a marine existence.

The specimen studied was a highly disarticulated Ophthalmosaurus fossil, from Dorset.  The fossil represents a three-metre-long individual from the upper part of the Ringstead Clay Member of the Sandsfoot Formation, Late Oxfordian faunal stage.  We estimate that this specimen is approximately 157-156 million years old (Jurassic).  The carcase came to rest on a shallow sea bed, the bones became scattered over an area of several square metres before final burial.  The break-up of the skeleton was probably caused by a combination of scavenging and the action of currents, possibly high energy water flows as a result of storm activity.

Trace Fossil Evidence

The researchers identified a wealth of trace fossil evidence indicating feeding on the carcase by scavengers as well as evidence of organisms grazing on the bones themselves.  Marks made by the teeth of fish were identified and the “star-shaped” feeding scratches from the ichnospecies Gnathichnus pentax were found.

An ichnospecies is an organism only known from trace fossil evidence. The strange five-pointed, star shapes etched over many of the fossilised reptile bones are very similar to the patterns made by living sea urchins with their five-toothed feeding apparatus.  Scientists have interpreted these star-shaped patterns on the bones as evidence of grazing by a prehistoric sea-urchin (echinoid), G. pentax. It would have been feeding on mats of algae that had formed.

Trace Fossil Evidence on the Ophthalmosaurus Bones

Rib showing sharp, narrow grooves (white arrows) probably left by the scavenging action of small fishes.

Picture credit: Nature Communications

The picture above shows a close up of an Ophthalmosaurus rib bone showing signs of having been scavenged by small fish. The arrows indicate potential bite mark evidence (scale bar = 0.5cm).

Evidence of Grazing on the Fossilised Bones by Echinoids (Sea Urchins)

G. pentax ichnospecies on a fragment of fossil rib.

Picture credit: Nature Communications

The photograph above (b) shows the tell-tale grazing pattern of the ichnospecies Gnathichnus pentax on one of the fossilised bones (scale bar = 1cm).

A Close up of the Star-Shaped Feeding Pattern

Scale bar = 0.2cm.

Picture credit: Nature Communications

The Mesozoic Equivalent of a Whale Fall Incident

Commenting on the study, Richard Twitchett (Natural History Museum), one of the research paper’s co-authors stated:

“This is the first time anybody has described the ecological succession in the Mesozoic equivalent of a whale fall in detail.”

When an extant whale dies and its body sinks to the seabed,  scientists have identified a number of distinct and sometimes overlapping ecological phases.  First, scavengers remove the flesh and other soft tissues from the carcase.  Then snails and the charmingly named bone-eating, snot-flower worms (Osedax genus) feast on the blood and the fluids from the decomposing remains.

The last phase sees the hard parts such as the bones themselves being digested by microbes which feed on the fats (lipids) stored in the bones.  Tube worms live off the microbes and the likes of the bone-eating snot-flower worms persist.

Feeding by Scavengers

When the insides of the Ophthalmosaurus’s bones were examined under powerful microscopes further evidence of feeding by scavengers was found.  A number of tiny, fossilised molluscs were discovered.  These are associated with the same ecological community phase now associated with the bone-eating, snot-flower worms.  However, there was no sign of the “sulphophilic stage”, in which oxidised inorganic compounds such as sulphides and methane, derived from microbial activity as the fats inside the bones are broken down are consumed by a chemosynthetic community.  The chemosynthetic community found on the carcases of whales in deep water (greater than two hundred metres) consists of free-living bacteria and bivalves (for example, the genus Beggiatoa).

Evidence of Microscopic Scavenging Activity within the Fossilised Bone

Close-up of the bioeroded area where microborings are perpendicular to the external bone surface

Picture credit: Nature Communications

The picture above (e) shows a highly magnified section of ichthyosaur bone (ib) and the adjacent micrite rim represents a fine-grained calcite layer formed by the action of microbes boring into the substrate.

Mats of Microbes

Instead, the ichthyosaur’s bones were colonised by mats of microbes which attracted sea urchins and other grazing invertebrates.  The bones also became the home for a number suspension feeders, such as oysters that cemented themselves to the remains of the skeleton, forming a miniature “reef phase” as described by the scientists.  The remains were eventually buried entombing the remnants of the ecosystem that had been established to exploit the last resources from the dead animal.

When large cetaceans perish, a reef phase is less likely to occur as most carcases settle in deeper water and the ubiquitous bone-eating snot-flowers rapidly destroy the skeleton.  The researchers conclude that shallow-water ichthyosaur falls do provide a range of ecosystem opportunities to other organisms similar to the ones seen in studies of dead whales and dolphins.  However, it seems such shallow water corpses do not support any specialised chemosynthetic communities.

Rukwatitan bisepultus – A Rare African Giant

Titanosaurs are a bit like buses, you wait for ages and then two of them come along together.  No sooner did we complete our synopsis on the research on the colossal Dreadnoughtus schrani, a newly described titanosaur from south-western Patagonia, then we have the opportunity to discuss another new species, this time from Africa.  This new titanosaur, named Rukwatitan bisepultus may not be quite as big as the newly described Dreadnoughtus but we at Everything Dinosaur estimate that fossils excavated from a hazardous cliff face in a steep quarry represent a dinosaur that was around ten metres long, or possibly much bigger.

Comparisons with the fossil bones from the Malawisaurus indicate that this titanosaur could have exceeded sixteen metres in length.  This herbivore would have been able to survey its floodplain home from a height of approximately four metres.

Rukwatitan bisepultus

An Artist’s Impression of the New Titanosaur (Rukwatitan bisepultus)

New genus of titanosaur described from Tanzania.

Picture credit: Mark Witton

Studying Titanosaurs

But with titanosaurs, size isn’t everything.  Rukwatitan may not be a record breaker in terms of its body mass but its discovery is perhaps more significant than the fossils of the South American giants.  This is only the fourth genus of titanosaur discovered in Africa* and the palaeontologists at the University of Ohio, who excavated the fossils out of the cliff over two field seasons, are confident that their find will help scientists to understand more about the global distribution and the diversity of the titanosaurids as well as helping to piece together more data on the evolution of sub-Saharan dinosaurs.

A Silhouette of Rukwatitan bisepulutus Showing Fossils Found

Scale bar = 1 metre

Picture credit: Eric Gorscak (Ohio University)

The picture above shows a bauplan of the new titanosaur and the position of the fossil bones that were found in relation to the body plan.

Titanosaurs are wide-bodied sauropods that probably evolved sometime in the Late Jurassic and survived until the Cretaceous mass extinction event.  They are the only sauropods known to have survived into the Late Cretaceous, but only in South America did these animals make up a significant proportion of the herbivorous megafauna, elsewhere, the ornithopods dominated.  When compared to other types of Sauropoda, titanosaurs tended to have wider bodies, due to the more robust and larger pectoral area (chest).  The limbs were strong and stocky, often the front limbs were longer than the hind limbs.

The spinal column was more flexible than in diplodocids, perhaps helping them to rear up more easily.  The heads were small, proportionately smaller than other types of sauropod.  Titanosaurs were geologically widespread and their fossils have been found on all the continents including Antarctica.  A number of sub-families have been identified and some of the titanosaurids are amongst the largest, terrestrial vertebrates known to science.

To read about the Antarctica fossil find (2011): Titanosaurs of the Antarctic.

The fossils were found in the Rukwa Rift Basin area of south-western Tanzania (hence the genus name).  Scientists from Ohio University in collaboration with several other universities have carried out a number of excavations from the Red Sandstone Group deposits, that form part of the Galula Formation.  Fossils of turtles, crocodilians and primitive mammals have also been found in the formation, as well as dinosaur remains.  The fossil bearing strata is believed to have been laid down approximately 100 million years ago (Late Albian faunal stage of the Cretaceous).

The Fossils were Excavated from a Steep Cliff Face

The fossils were excavated from a steep cliff.

Picture credit: Patrick O’Connor (Ohio University)

The vertebrates associated with the Galula Formation have shown some unique anatomical features indicating that the floodplain environment which is represented by these sandstone deposits may have been separated from other parts of Gondwana, permitting a unique fauna to evolve.  Last year, scientists from Ohio University reported the discovery of a new type of crocodilian (Rukwasuchus yajabalijekundu) that was different from other crocodilians found in deposits of the same geological age but from further north.

Some of the Fossils Exposed after Excavation

Fossil material exposed.

Picture credit: Ohio University

One of the authors of the scientific paper, published in the “Journal of Vertebrate Palaeontology”, Patrick O’Connor (Professor of Anatomy at Ohio University) stated:

“There may have been certain environmental features, such as deserts, large waterways and/or mountain ranges that would have limited the movement of animals and promoted the evolution of regionally distinct faunas.  Only additional data on the faunas and the palaeo-environments from around the continent will let us further test such hypotheses.”

Two Caudal Vertebrae (Tail bones) from the Site

A number of caudal vertebrae including several articulated vertebrae have been found.

Picture credit: Ohio University

* Team members have had a go at naming the four genera of African titanosaurs currently described, here we go:

1. The basal titanosaur from Tanzania (Upper Tendaguru Formation) – Janenschia robusta (Late Jurassic)
2. The Lithostrotian titanosaur from Malawi (unknown formation) Malawisaurus dixeyi (Cretaceous)
3. The basal Lithostorian titanosaur? Rukwatitan bisepulutus (described above)
4. The Lithostrotian titanosaur from Egypt (Bahariya Formation) Paralititan stromeri (Late Cretaceous)

To read the acclaimed article written by Everything Dinosaur on the newly discovered titanosaur Dreadnoughtus: New Titanosaur from South-Western Patagonia.