Category: Dinosaur and Prehistoric Animal News Stories

Pterosaur Named after Avatar Dragon

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”.

One of the Newly Described Pterosaur Fossils

White scale bar =

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.   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?

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).

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.

Creature from a Film Inspires Pterosaur Name

Note the long, orange coloured crest on the lower jaw

Note the long, orange coloured crest on the lower jaw

Picture Credit: 20th Century Fox

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.  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".

A flock of Ikrandraco Pterosaurs “fishing”.

Picture Credit: Chuang Zhao

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

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.

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).   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.

Ancient Mammal Named after Mick Jagger

Jaggermeryx naida – “Jagger’s Water Nymph”

It resembled something akin to a skinny hippopotamus crossed with a long-legged pig and spent most of the time in the warm, freshwaters of tropical North Africa, but the biggest claim to fame for a newly described member of the Anthracotheres (extinct family of hoofed mammals), is that it has been named after the lead singer of the Rolling Stones.  Sir Mick Jagger is famous for his big mouth and lips and it seems these are traits he shared with Jaggermeryx naida, which roamed the ancient waterways of Egypt some 19 million years ago (Burdigalian faunal stage of the Miocene epoch).  The name means “Jagger’s water nymph” and we will avoid any references to the Rolling Stone’s front man and his age.

Views of the Jaw Fragment of J. naida

Various views of the fossil material.

Various views of the fossil material.

Picture Credit: Greg Gunnell (Duke Lemur Centre)

The picture above shows views of the jawbone fragment that led to the identification of this new species of hoofed mammal.  Picture 1 is a view of inside of the jaw (medial), picture 2 shows the same fossil but in lateral view (outside of the jaw) and picture 3 shows the same fossil viewed from the top (dorsal) view.

An international team of scientists have been carefully excavating an area of the Qattara Depression (north-western Egypt).   Although the Qattara depression forms part of the Libyan desert today and it is famous for its dunes, salt lakes and arid terrain (it was the setting of the 1958 film “Ice Cold in Alex”), back in the Miocene epoch, much of North Africa was covered in lush swamplands and a number of Anthracotheres thrived.  The paper reporting on the excavation of the Anthracothere specimens has been published this week in the academic “Journal of Paleontology”, (note the American form of spelling).

The site, known as Wadi Moghra has provided the highest diversity of Anthracothere fossils when compared to other locations of Miocene aged deposits.  A spokes person from Everything Dinosaur commented that at least six different types of these hoofed mammals are now known to have been living in this part of the world nineteen million years ago.

Associate Professor Ellen Miller, of Wake Forest University (North Carolina), one of the co-authors of the scientific paper stated:

“We imagine its lifestyle was like that of a water deer, standing in water and foraging for plants along the river bank.”

 Ellen Miller (Wake Forest University) at Work Examining Fossil Material at the Site

Often palaeontology can involve lying down on the job.

Often palaeontology can involve lying down on the job.

 Picture Credit: Wake Forest University

The “Jagger” Connection

The site has revealed a number of vertebrate fossils, not just artiodactyls (even-toed mammals), but the fossilised remains of catfish, turtles and a number of water birds have also been found.   The fossil jaw fragments showed a series of eight holes.  These have been interpreted as having been the sites of large nerves that fed information back to the brain from the lower lip and snout.  Jaggermeryx naida probably had large lips (just like the Rolling Stones singer) and a super-sensitive lower lip and snout.  These adaptations would have enabled this herbivore to forage for nutritious plants in the muddy waters of this ancient Egyptian landscape.

A sensitive lower lip and snout.

A sensitive lower lip and snout.

Picture Credit: Wake Forest University

Associate Professor Miller added that the first fossils of this animal that they have described were found back in 1918, but at the time it was not recognised that these fossils represented a new type of Anthracothere.

She commented that when the team asked fellow researchers had they seen similar looking bones elsewhere:

“When people kept telling us no, we knew we were really on to something.  They’ve [Jaggermeryx naida] have been around for nearly a Century, we just didn’t know what they were.”

Mick Jagger is not the first celebrity to have a prehistoric animal named after him.   Many famous people have been honoured in this way.  For example, last summer (June 2013), Everything Dinosaur reported on the fact that an Eocene lizard had been named after Jim Morrison (lead singer of the Doors).  Earlier in 2013, we reported on a new type of Cambrian Arthropod being named after the actor Johnny Depp.

To read about the Eocene lizard named after Jim Morrison: Rock Star Honoured

To read about the Cambrian invertebrate named in honour of Johnny Depp: Film Star Honoured by Having Arthropod Fossil Named After Him

Spinosaurus “Four Legs are Better than Two”?

Spinosaurus – Steps into the Spotlight (Once Again)

And so, the long awaited paper that re-evaluates the fossil data on the Spinosaurus genus and specifically S. aegyptiacus was published in the academic journal “Science” yesterday.  Time to open a new chapter on this, one of the most enigmatic, mysterious and bizarre of all the known Theropoda.  Since the paper’s submission in the summer, there has been a lot of debate in scientific circles with regards to what this new study will show.  The paper’s title “Semi-aquatic Adaptations in a Giant Predatory Dinosaur”, is almost an understatement, when this is contrasted with the lurid headlines we have seen from a large number of media outlets.

Re-examining What We Thought We Knew About Spinosaurus

In very brief summary, the dedicated team of international researchers have re-assessed the known fossil material on Spinosaurus.  They have been able to track down the location in Morocco from which a number of Spinosaurus bones were excavated and sold via a fossil dealer.  The team have then re-examined this site and found further material.  Their efforts has led to a considerable re-think in terms of what this animal looked like and how it moved.  This new study interprets Spinosaurus as a sixteen metre plus dinosaur, that considered itself more at home in the water than on land.  Although capable of terrestrial locomotion, unlike every other large Theropod, a new rendering sees Spinosaurus as an obligate quadruped.  Here is a meat-eating dinosaur that walked on all fours.

A Semi-Aquatic Obligate Quadruped – Spinosaurus

Very much at home in the water.

Very much at home in the water.

Picture Credit: Davide Bonnadonna, Nizar Ibrahim, Simone Maganuco

In the picture above, a web-footed Spinosaurus pursues a prehistoric swordfish, known as Onchopristis.  Earlier studies and research based on other members of the Spinosauridae suggest that fish may have made up a substantial proportion of their diet.  Instead of perching on the river bank, attempting to claw fish out of the water like some form of giant, prehistoric Grizzly bear, an ecological niche trumpeted by ourselves to the CGI team helping with the rendering of Spinosaurus for an episode of the BBC television series “Planet Dinosaur” back in 2011, this latest interpretation goes a lot further.

Beyond “Planet Dinosaur” – The Transformation of Spinosaurus aegyptiacus

From paddler to swimming the "evolving" image of Spinosaurus.

From paddler to swimming the “evolving” image of Spinosaurus.

Picture Credit: BBC

Building Up a New Picture

Having re-visited what records and remaining photographs that exist of the original Stromer material excavated from the Western desert of Egypt around a 100 years ago, the dedicated research team then set about mapping previously known Moroccan finds including jaw bone fossils that had been discovered in the mid 197o’s.  To this eclectic mix they added information obtained from the fossils from the newly “rediscovered” Moroccan site, which itself makes up what is now known as the neotype for Spinosaurus aegyptiacus.  A neotype is a specimen that is deemed to represent a species in the absence of the holotype material that has either been lost or destroyed.  Add a pinch of material not known from the Spinosaurus genus but described from related animals baryonychids, spinosaurids and so forth, combined with a soupcon of inferred parts of the anatomy as the bones are not known at all in the fossil record and you have a “composite” view of the animal.

The Latest Interpretation of Spinosaurus (S. aegyptiacus)

Life-size reconstruction and supplemental figure

Life-size reconstruction and supplemental figure

Picture Credit: Davide Bonnadonna (top) Ibrahim et al (bottom)

The illustration (top), depicts Spinosaurus as a dinosaur that walked on four legs, in this new study the centre of gravity is positioned further forward, the pelvic girdle is estimated to have been much smaller and the hind limbs with their robust but very short femur  reflect the adaptations of a paddler more than that of a bipedal walker.

The picture below, referred to by a colleague as the “Spinosaurus colour chart” is a figure from the scientific paper’s supplementary data.  The colour coded bones illustrate the composite nature of this digital reconstruction.

The “Spinosaurus Colour Chart” Key

RED = the neotype fossils (FSAC-KK 11888)

ORANGE = the original bones from Stromer’s expeditions

YELLOW = isolated fossil material ascribed to Spinosaurus spp. from the same geological Formation as the neotype (Kem Kem Formation)

GREEN = scaled up bones derived from better known spinosaurids

BLUE = additions to help complete the skeleton based on no known fossils but derived from adjacent bones in the digital restoration

We at Everything Dinosaur applaud the efforts of the international team responsible for this new reconstruction.  A revaluation of the known Spinosaurus fossil material has been long overdue and this is the first time that palaeontologists have been able to relocate the bones from a private fossil collection to the actual site where they were excavated.  We commend the team for their perseverance.

Taking a Different Perspective

However, as with all good science, a number of counterpoints have already been made.

Scott Hartman, addresses these concerns in his web log: There’s Something Fishy About Spinosaurus

Scott, with a background in anatomy, and an expert in skeletal reconstructions, makes a number of excellent points in his article.

The dinosaur referred to as Spinosaurus aegyptiacus was one of the last of the Spinosauridae.  There is a British connection to this story.  One of the spinosaurids used in the comparative study was Baryonyx (B. walkeri).  When this dinosaur, whose bones were found in a Surrey clay pit, was formally described back in 1986 it was depicted as a semi-aquatic dinosaur, fish scales found in the body cavity suggested that fish made up at least a portion of its diet.

Commenting on this new research, Dean Lomax, (Honorary Visiting Scientist: School of Earth, Atmospheric and Environmental Sciences, The University of Manchester) and author of the recently published “Dinosaurs of the British Isles” which includes extensive information on the Baryonyx fossil finds, stated:

“The new discovery is very interesting as it potentially confirms what had been suspected for quite some time, that Spinosaurus lived a semi-aquatic lifestyle.”

For further information on the book “Dinosaurs of the British Isles” by Dean Lomax and Nobumichi Tamura, which includes some fantastic skeletal drawings by Scott Hartman visit: Siri Scientific Press

This new paper, marks a new chapter in the story of Spinosaurus, but it’s not the end of the story that’s for sure.  Ironically, although Stromer originally depicted S. aegypticacus as a biped, we recall that in the distant past (the 1970′s), Spinosaurus had previously been thought of as a dinosaur that walked on all fours.

An Illustration of Spinosaurus from 1976

Spinosaurus as a terrestrial quadruped.

Spinosaurus as a terrestrial quadruped.

Picture Credit: Giovanni Caselli (from the book “The Evolution and the Ecology of the Dinosaurs” by L. B. Halstead)

We suspect there are going to be a few more twists and turns in the Spinosaurus story.

What Happens when an Ichthyosaur Dies?

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.  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)

Ichthyosaurus Model (Carnegie Collectibles)

Picture Credit: Everything Dinosaur/Safari Ltd

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.

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.

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.

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.

Scale bar = 0.2cm.

Picture Credit: Nature Communications

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.

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

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.

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.

New Species of Titanosaur Named – Rukwatitan bisepultus

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.

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

New genus of Titanosaur described from Tanzania.

New genus of Titanosaur described from Tanzania.

Picture Credit: Mark Witton

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

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.

The fossils were excavated from a steep cliff.

Picture Credit: Patrick O’Connnor (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.

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.

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

Fossil Damaged at Dinosaur National Monument (Utah)

Dinosaur Fossil Damaged and a Piece Stolen from Dinosaur National Monument

It once was a near perfect fossil of the upper arm bone of a Sauropod dinosaur, now it is broken and damaged with a fist-sized chunk missing.  Rangers at the Dinosaur National Monument in Utah have reported the vandalism and theft of part of a humerus.  It is extremely sad to have to report on yet another theft of a dinosaur fossil, officials at the Monument are appealing to members of the public to help them trace the culprit(s).

The Damaged Portion of the Dinosaur Fossilised Bone

The damaged dinosaur bone.

The damaged dinosaur bone.

Picture Credit: National Parks Service

The picture above shows the missing section of the dinosaur bone, the bone seems to have been deliberately smashed.

The Dinosaur National Monument is well-named.  Managed by the United States Department of the Interior National Parks Service, the park covers some 85,000 hectares and overlies the border between the states of Colorado and Utah (although the main dinosaur quarry site is in Utah, close to the town of Jenson).  The Monument is world famous for its amazing collection of dinosaur and other vertebrate fossils which date from the Upper Jurassic.  At least ten different types of dinosaur genera are known from the Morrison Formation exposures.  The Utah sequence represents high energy riverine deposits and on show at the visitor centre is a sandstone “wall” that reveals some 1,500 dinosaur bones.  Dinosaurs were probably swept away and drowned during floods.  At bends in the river as the current slowed down, so debris, including the carcases of dinosaurs was deposited.  The Dinosaur National Monument preserves these “log jams” of dinosaur bones.  Genera associated with the Monument include Camarasaurus, Allosaurus, Stegosaurus, Apatosaurus, Diplodocus and Dryosaurus.

On Tuesday, September 2nd , a park ranger was leading a tour party along the Fossil Discovery Trail when the damaged bone was noticed.  The vandalism and theft probably took place sometime between the Monday guided walk along the Fossil Discovery Trial and Tuesday morning.  The Fossil Discovery Trail is a 1.2 mile trail that runs between the Quarry Visitor Centre and the Quarry Exhibit Hall where the famous sandstone “wall”of dinosaur bones that we described above, is located.  The trail is unique as it is one of the few places where visitors can hike to see and touch dinosaur fossils and fragments in situ.  It allows visitors to experience what it may have been like for palaeontologist Earl Douglass (Carnegie Museum of Natural History), when he discovered the first fossils in what is now the Monument.

A spokes person from Everything Dinosaur commented:

“This is such a shame as the Dinosaur National Monument is going to celebrate its centenary next year and to have fossils damaged and stolen is deeply upsetting.  Although the fossils along the trail are of limited scientific value they provide a wonderful opportunity for members of the public to get up close to real dinosaur fossils.”

The Sauropod Humerus (before and after) Photographs

Two photographs showing the fossil before and after the theft.

Two photographs showing the fossil before and after the theft.

Picture Credit: National Parks Service

The picture above shows two photographs, the picture of the humerus without the damage (left) and a close up showing the damaged portion (right).  Although our dinosaur experts cannot be certain, the bone portion in question looks like the distal end of a left humerus, probably part of a Camarasaurus.  Park officials are seeking help from the public and anyone with information regarding this theft are invited to contact staff on (435) 781-7715.  A reward of $750 USD has been put up by the Intermountain Natural History Association for information that leads to a conviction.

The Part of the Fossil Discovery Trail where the Bone was Situated

The arrow shows the position of the damaged dinosaur bone.

The arrow shows the position of the damaged dinosaur bone.

Picture Credit: National Parks Service

Everything Dinosaur would like to take this opportunity to stress that visitors to the Dinosaur National Monument are not allowed to collect/damage any fossils or rocks.  Under Federal law, all features, artifacts and resources are protected. No collection of park geological resources for commercial sale, private collections or for classroom educational purposes is permitted.  We advise all visitors to National State Parks of America to familiarise themselves with the various protection laws and polices that relate to that particular location.

A Little Detail on a Great Big Dinosaur – Dreadnoughtus

Dreadnoughtus schrani – A Dinosaur on a Massive Scale

And so the announcement came this week about the discovery of a super-sized, South American dinosaur that weighed as much as thirteen, bull African elephants.  Dreadnoughtus was so named as the huge bones (and for a change when it comes to the Titanosauria, there are quite a lot of them), reminded the scientists of the impervious super-structure of turn-of-the-Century battleships.  This was a plant-eating dinosaur that was simply too big to be vulnerable to attack from predators.  Invulnerability would have been very handy for this immense creature as this dinosaur would have been preoccupied with eating, trying to cram enough calories into its enormous digestive system to keep its house-sized body functioning.

A Dinosaur on a Massive Scale - Dreadnoughtus schrani

Huge dinosaur from southern Patagonia.

Huge dinosaur from southern Patagonia.

Picture Credit: Jennifer Hall

Many articles have already been written about this new Titanosaur, the scientific paper was published by the Nature Publishing Group on the 4th September, this paper has already received more than 20,000 page views and the story has been picked up by dozens of news outlets.  We at Everything Dinosaur, had known about this research for some time, there are more exciting titanosaurid discoveries from South America still to be announced, so this blog article hopes to recap the main points about the significance of this study and to focus on a couple of areas that may not have been covered by other media outlets.

Firstly let’s deal with the size – this is a real “elephant in the room” moment, as with all large dinosaur fossils, this seems to be the most prominent and frequently asked question – just how big was this dinosaur?

The Size and Scale of the Dinosaur Discovery

Heavier than a 737 Jet.

Heavier than a 737 Jet.

Picture Credit: Dr. Ken Lacovara

Although D. schrani may not be the very biggest of all the dinosaurs that ever existed.  It is certainly right up there, with an estimated body mass of 59,300 kilogrammes (the actual measurement was 59,291 kilogrammes but some rounding has taken place in the media).

How do Scientists Estimate the Body Mass?

This leads us to one the most important points to note about this discovery.  The international research team led by Drexel University’s Dr. Kenneth Lacovara was able to recover around 45% of the total skeleton of a single individual specimen, including cranial material (skull bones).  Most of the rear portion of the animal was excavated including a left humerus (upper arm bone) and femur (thigh bone).  These limb bones hold the key to estimating body size.  Earlier studies have shown that an analysis of the these limb bones and measurements of their circumference, corresponds to relative body mass in terrestrial quadrupeds.

Put simply, imagine weighing several different herds of cows before they are slaughtered for meat.  The cows would be of different sizes and therefore there would be some variance in total body weights.  Once the cows had met their demise, the upper arm bones and thigh bones could be collected for each animal.  The mid shaft circumference for these bones would then be measured and recorded.  A correlation would most likely be found between the mid shaft circumference measurements and the body weight recorded earlier.  For instance, bigger circumference equals a heavier animal.

This correlation provides accurate data on the body mass estimates of four-limbed, terrestrial animals that are alive today.  So the theory goes, that if it works for animals that are extant (living today), then it should also work for extinct animals such as the Dinosauria.  This correlation is extremely useful as the Sauropods and the later Titanosaurs are so different from living creatures that anatomical comparisons are just not relevant.

The preservation of these limb bones which have been found to scale with body mass, permits the scientists to make an estimate of the body mass of Dreadnoughtus schrani.  The same equation has been used to estimate the body masses of a number of other substantial dinosaurs, but none of them quite match the bulk of Dreadnoughtus.  It therefore suggests that the Dreadnoughtus schrani holotype material represents an individual titanosaurid that was much heavier than other Titanosaurs and indeed much more massive than most other Sauropods.

Dreadnoughtus Compared to Other Sauropoda (Limb Circumference Analysis)

Dreadnoughtus - the most complete skeleton of a giant titanosaurid dinosaur discovered to date.

Dreadnoughtus – the most complete skeleton of a giant titanosaurid dinosaur discovered to date.

Table Credit: Everything Dinosaur, data compiled from Nature Publishing Group and Benson et al.

Still Growing?

Astonishingly, of the two specimens found together, the largest one, the Dreadnoughtus that was estimated to be heavier than a Boeing 737 aircraft was probably not yet fully grown.  Identifying when a dinosaur reached its maximum size is a complicated business (related to indeterminate growth), however, the research team found that it was likely that this super-sized dinosaur was still growing at the time of its death.  The scapula (shoulder blade) had not fused completely to the coracoid bone.  The posteromedial margin of the coracoid foramen (small opening, located in the middle of the coracoid), was butted up against the distal portion of the shoulder blade.  Palaeontologists have cited these conditions as indicating that the individual was still growing.  A study of the humerus supports this hypothesis, the lack of lines of arrested growth indicate that this dinosaur was immature at the time of death.  Although some scientists have questioned the validity of these indicators, whatever the outcome, the larger individual of the two Dreadnoughtus specimens found to date, represents the biggest dinosaur known to science for which a robust body mass has been calculated.

Not reported by many media sources but for the record the femur length is in excess of 1.9 metres and the humerus is 1.6 metres long.

Dinosaur Fossils Found in Southern Patagonia

Another, significant point we wanted to make concerns the location of the dinosaur fossils.  Whilst Patagonia may now be synonymous with dinosaur discoveries, Argentinosaurus, Giganotosaurus et al, many of these fossils come form the northern and central parts of this vast region.  These fossils come from a relatively unexplored part of south-western Patagonia.  The fossil material was excavated from the Cerro Fortaleza Formation, an exposure on the eastern bank of the Río La Leona, (Santa Cruz Province), this is more than 750 miles (1,200 kilometres) away from the location of other major Cretaceous-aged dinosaur fossil finds.  We at Everything Dinosaur are unaware of any radiometric dating and although Campanian-aged biostratigraphical material is associated with some horizons of the Cerro Fortaleza Formation, the precise age of these fossils remains unclear.  They are between 83 million and 66 million years old, with some sources stating 77 million years of age (Campanian to Maastrichtian faunal stages).

Location of the Dreadnoughtus Quarry

The site of the fossil discovery.

The site of the fossil discovery.

Picture Credit: Map de la provincia de Santa Cruz

A Team Effort

Last but not least, the 116 fossils, some of which do show potential evidence of scavenging by Theropod dinosaurs, have been excavated, prepared and digitally mapped by a dedicated team of researchers.  This has certainly been a colossal undertaking, yes, we know the tail itself measures some thirty feet in length, (the total length of Dreadnoughtus schrani has been estimated at 26 metres) and the skull (only one fragment of which has been found) was around eighty-eight centimetres in length.  It is quite right to focus on the huge size of this member of the Titanosaur family, but we at Everything Dinosaur would like to take this opportunity to thank all the researchers for their hard work.

The first fossil was spotted during a expedition back in 2005, the femur we think. From 2005 to 2009 a series of field trips took place to excavate the two individual specimens, since then a great deal of preparatory work and fossil prep has been carried out by scientists from Drexel University, a number of graduates from this institution but also with the aid and support of the likes of the Carnegie Museum of Natural History,  the Museo Argentino de Ciencias Naturales, Argentina and Laboratorio de Paleovertebrados, Universidad Nacional de la Patagonia (also Argentina).

Even a scientist from the University of Manchester (Dr. Victoria Egerton), a lecturer in Applied Palaeontology, was involved.   Our congratulations to everyone who has participated in this amazing study, an exceedingly rare opportunity to learn about one of the largest terrestrial vertebrates that is known to science.

Fresh Rockfalls at Monmouth Beach (Lyme Regis)

Warnings for Fossil Hunters at Lyme Regis

The cliffs that surround the picturesque town of Lyme Regis in Dorset on England’s famous “Jurassic Coast” are very treacherous.  Rockfalls and landslips are a relatively common occurrence and team members at Everything Dinosaur, have done much to help inform and to warn visitors to the area of the potential hazards.  Fossil collecting or simply exploring the beaches can be a lot of fun, but the recent cliff fortification and shore stability measures put in place by the local council will not solve the problem of the unstable geology of the area.   The cliffs are composed of relatively loose sediment, that when saturated after heavy rain or somewhat dried out after a prolonged spell without too much precipitation, are prone to rockfalls.  It is always advisable to stay well away from the base of the cliffs, fossil collecting on a falling tide helps, as this gives an increasing distance between the sea and the cliffs.

Dangerous Cliffs at Lyme Regis

Good idea to go fossil collecting on a falling tide and to keep away from the steep cliffs.

Good idea to go fossil collecting on a falling tide and to keep away from the steep cliffs.

Picture Credit: Everything Dinosaur

Recently, we were sent some photographs by Lyme Regis fossil expert, Brandon Lennon.  The photographs showed a rockfall that had taken place on Monmouth beach (to the west of Lyme Regis).  Brandon explained that he had observed a number of cliff falls this year and that he expected more to occur as the autumn weather sets in.   This particular rockfall had occurred on that area of the beach famous for its extensive ammonite and nautiloid fossils preserved within the blue lias limestones – an area known as the “Ammonite Pavement” or the “Ammonite Graveyard”.

Recent Rockfall at Monmouth Beach

Rockfall onto the Ammonite Pavement on Monmouth Beach.

Rockfall onto the Ammonite Pavement on Monmouth Beach.

Picture Credit: Everything Dinosaur

A supervised, fossil collecting walk is one of the best ways to explore the beaches around Lyme Regis, for further information on such tours: Fossil Walks in the Lyme Regis Area

Perhaps if you are lucky enough to go on a field trip with Brandon to Monmouth beach, you might be able to hear the theories that have been proposed to help explain why so many large ammonite fossils are found together at this spot.

Everything Dinosaur was sent a beautiful piece of fossilised wood from nearby Portland.  The specimen still had the bark preserved on it and when polished in section, growth rings could still be made out. We think that the fossil represents an Araucaria spp. (monkey puzzle tree).  This fossilised wood dates from the Upper Jurassic.  Fossil wood can occasionally be found on the beaches of Lyme Regis and nearby Charmouth, but this is usually much older dating mainly from the Lower Jurassic.

A Polished Section of Fossilised Wood

A polished section of fossilised wood.

A polished section of fossilised wood.

Picture Credit: Everything Dinosaur

Remember if fossil collecting, be careful out there.

Did Psittacosaurus Use Baby Sitters?

Palaeontologists Suggest Dinosaur Fossil Material Shows a “Creche” with Baby Sitter

A team of international researchers have re-examined a set of Psittacosaurus dinosaur fossils that come from the Lujiatun beds of the Yixian Formation in Liaoning, China.  The rock slab has preserved the fossilised remains of twenty-four young Psittacosaurs and one older individual.  It has been suggested that the fossil represents a group of hatchlings being looked after by an older animal.  Could this be evidence of a dinosaur “creche” with a “baby sitter”?

The paper on this new research has been published in the academic journal “Cretaceous Research”.  The international team included University of Pennsylvania based scientists Brandon P. Hedrick and Peter Dodson as well as researchers from China’s Dalian Museum of Natural History, where the rock slab is currently stored.  The fossil material was first described ten years ago, the block, which measures a little over sixty centimetres in length was discovered by an amateur palaeontologist, it is believed to date from around 120 million years ago (Aptian faunal stage of the Cretaceous).

Psittacosaurus is one of the most studied of all the dinosaurs.  A number of species have been assigned to the genus, it remains the most specious of all the Dinosauria, although some species have been described as nomen dubium following a recent review (2013).  Seen as a transitional form between the Ornithopods and the horned dinosaurs, Psittacosaurus is regarded as a basal member of the Marginocephalia.  Rarely exceeding two metres in length, fossils of this herbivorous dinosaur have been found in China, Russia and Thailand.

An Illustration of Psittacosaurus

A typical psittacosaurid.

A typical psittacosaurid.

Picture Credit: Everything Dinosaur

Despite its spectacular appearance, the fossil material has only been briefly described, although the idea of a “dinosaur creche” has been proposed before.  The exact location of the discovery was never recorded, this hampered the international research team but as PhD student Brandon P. Hedrick stated:

“I saw a photo of it [the block] and instantly knew I wanted to explore it in more depth.”

Dalian Museum of Natural History Slab of Fossil Material

Is this evidence of a dinosaur creche with a baby sitter?

Is this evidence of a dinosaur creche with a baby sitter?

Picture Credit: Everything Dinosaur/University of Pennsylvania

In order to learn more about how these dinosaurs may have died, the orientation of their bodies was carefully studied.  Thin slivers of rock were examined under the microscope and further samples were subjected to X-ray diffraction.  The analyses suggested that the matrix was composed of volcanic material, indicating that these prehistoric animals were caught in a flow of material as a result of a volcanic eruption.  Since all the fossils were orientated in the same plane, the position of the fossils supports this idea that all these dinosaurs were engulfed in a flow.

As the fossilised bones showed no scorch marks or signs of heat damage, the researchers concluded that the flow was unlikely to be pyroclastic in nature.

Hedrick added:

“If they were captured in a flow, the long axis, their spines, would be orientated in the same direction.  That was what we found.  They were likely trapped by a flow.”

It is likely the flow was some sort of lahar – a mixture of water, mud, rock and other debris associated with volcanic eruptions.

Since no egg shell material has been found, it is believed that the twenty-four fossils represent a group of hatched dinosaurs.  The larger skull was found in close association with the fossil material, it is likely that this larger Psittacosaurus perished at the same time as the younger animals.  All the Psittacosaurs have been assigned to the same species Psittacosaurus lujiatunensis, the skull probably belonged to an immature adult, one not old enough to breed, so the researchers have hypothesised that this was an older sibling helping to care for its younger brothers and sisters.

Family members helping out to raise the following year’s brood is a type of behaviour found in a number of bird species.  It has been estimated that around 8% of all, extant bird species are involved in some form of co-operative breeding in which other family members help to raise young.  This behaviour is found in many types of song bird and the crow family for example.  The scientists emphasise that this material cannot be regarded as a dinosaur “nest”.

Hedrick explained:

“It certainly seems like it might be a nest, but we were not able to satisfy the intense criteria to say definitely that it is.  It is just as important to point out what we don’t know for sure as it is to say what we are more certain of.”

The scientists hope to continue their work by focusing on the micro-structure of the fossilised bones of the smaller dinosaurs to establish whether they were all at the same stage of development.  If this is found to be the case, this would support the theory that this rock slab represents the preserved remains of one clutch or brood of animals.

In Pursuit of the “Shiva” Crater and Dinosaur Extinction

In Search of Dinosaur Extinction Theories – The “Shiva” Crater

The controversial tear-drop shaped Shiva crater located off the western coast of India has divided opinions for decades.  Whilst many people may be familiar with the extraterrestrial impact theory that led to the end Cretaceous mass extinction event, most would argue that the Chicxulub crater located off the coast of the Yucatan peninsula (Mexico) is the most likely candidate for that “smoking gun” evidence to indicate that a large body from outer space crashed into the Earth.  Not so, according to Professor Sankar Chatterjee and his colleagues.  Professor Chatterjee, a Horn Professor of Palaeontology and the Curator at the Museum of Texas Tech University, believes that an object from space perhaps a comet or an asteroid, some forty kilometres in diameter smashed into the Earth around sixty-six million years ago and this too contributed to the Cretaceous-Palaeogene extinction event.

The Shiva crater is named after the Hindu god of destruction, transformation and renewal.  It is estimated to be around six hundred kilometres in length and around four hundred kilometres across at its widest part.  Professor Chatterjee has been awarded the prestigious “Fulbright-Nehru Academic and Professional Excellence Award”, which includes a grant which the Indian-American scholar intends to use to fund a visit to Western India next spring to continue his research on the crater.  The Fulbright Programme is an international educational exchange programme sponsored by the Government of the United States with the aim of increasing mutual understanding between the people of America and the rest of the world.  Professor Chatterjee will join the Koyna Drilling Project and analyse rock cores drilled through the sea bed in a bid to establish the age of this geological phenomena and to learn more about its formation.

Professor Sankar Chatterjee (Texas Tech University)

Our congratulations to the Professor.

Our congratulations to the Professor.

Picture Credit: Texas Tech University

The crater was discovered when geophysical surveys of the Mumbai Offshore Basin revealed a huge, tear-drop shaped depression in the strata that forms the western continental shelf of India.  The crater is buried under layers of rock which are between two kilometres and seven kilometres deep.  Professor Chatterjee explains that the strange shape of the crater may have been caused by the shallow angle of trajectory or by subsequent rock falls or as a result of ancient volcanic activity – after throws of the immense volcanism that led to the formation of the extensive Deccan Traps.  The area is believed to hold vast reserves of fossil fuels, both crude oil and natural gas.

It is hoped that this new research will confirm that this crater was caused by an extraterrestrial impact, a theory challenged by a number of scientists and academics who contend that this feature does not represent an impact crater at all.  The Shiva crater for example, is not recorded on the Earth Impact Database of the Planetary and Space Science Centre at the University of Brunswick (Canada).

The Site of the Shiva Crater in Relation to the Deccan Traps

The estimated location of the Shiva Crater.

The estimated location of the Shiva Crater.

Picture Credit: Everything Dinosaur

Last year, Everything Dinosaur reported on some new research carried out by an international team of scientists that dated the Chicxlub crater to 66,038,000 years ago (plus or minus 11,000 years).  This was the most accurate date proposed yet and places the impact event at around the time of the extinction event that wiped out the dinosaurs and about seventy percent of all terrestrial life.

To read more about this research: Most Accurate Date Yet Established for Chicxulub Impact Crater

It has also been suggested that no, one single extraterrestrial impact event was the cause of the extinctions.  Indeed, it has been suggested that the dinosaurs, pterosaurs and other groups that perished may have been subjected to more than one Earth/space collision.  In addition, Everything Dinosaur reported last year on research that proposed a comet was the most likely culprit for the Yucatan peninsula impact.

To read this article: American Researchers Propose Comet Caused the Chicxulub Crater

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