Dinosaur Ridge Reveals Evidence of Dromaeosaurs

Welsh palaeontologist Dr Martin Lockley of the University of Colorado Denver, has identified the tell-tale, two-toed tracks of dromaeosaurid dinosaurs from strata from the eastern side of the famous Dinosaur Ridge location to the west of the “mile high city”.  This is the first time dromaeosaurid tracks have been found in the State, only sixteen other dromaeosaurid trackways have been documented to date, most of these come from China or South Korea.  There has only ever been one other two-toed trackway discovered in the whole of North America.

Cedar Mountain Formation

This site from the Cedar Mountain Formation of eastern Utah (the Mill Canyon Dinosaur Tracksite), has preserved didactyl tracks that have been given the ichnogenus Dromaeopodus.  Dr Lockley played a key role in the study of the eastern Utah fossils.  These trace fossils like the Colorado material, date from the Cretaceous, however, the Dinosaur Ridge tracks are a little younger having been made some 105 million years ago, whereas, the Mill Canyon strata (from the Ruby Ranch Member of the Cedar Mountain Formation), are believed to date from around 112-115 million years ago.

Dromaeosaurid Track and Illustration (Dinosaur Ridge Location)

The two-toed track and an illustration showing how the footprint was made.

Picture credit: University of Colorado Denver (photograph), Matt Celeskey illustration with additional annotation by Everything Dinosaur

Raptor Tracks

The picture above shows one of the tracks identified by the research team as dromaeosaurid.  In these types of dinosaurs, also referred to as the “raptors”, the second toe possessed a huge sickle-like claw which was held off the ground.  In essence, these dinosaurs moved around on just two toes (toes III and IV), hence, only two toe impressions can be seen in the footprint.

Films like “Jurassic Park” and “Jurassic World” have popularised the “raptors”, dinosaurs like Velociraptor and Utahraptor for example.  The illustration above by Matt Celeskey is based on Utahraptor, the largest dromaeosaurid known, although recently Everything Dinosaur reported on the discovery of fossils from another huge “raptor”, but one that lived much later in the Cretaceous – Dakotaraptor.

To read an article about the discovery of Dakotaraptor: Dakotaraptor – A Giant Raptor.

An Model of a Typical Dromaeosaurid

The Papo feathered Velociraptor model.

Picture credit: Everything Dinosaur

Agile Dinosaurs

It is believed that these agile dinosaurs were covered in shaggy coats of proto-feathers and that they may have been pack hunters.  Dromaeosaurids ranged in size from about as big as chickens to giants that were as long as Saltwater crocodiles.

To read about the discovery of a new species of dromaeosaur from Canada that Everything Dinosaur reported on last year: Sniffing Out a New Dinosaur Species.

Dr Martin Lockley Holding a Cast of a Footprint

Two toes can be clearly seen

Picture Credit: University of Colorado Denver/Channel 9 News

Dr Lockley’s thumb marks the place where the sickle-toed claw would have been, but it has left no impression as it was raised off the ground, only the pes prior to the claw itself has left an impression.  The track represents a left foot.  A paper detailing the discovery is due to be published in the academic journal “Cretaceous Research”.

A Significant Fossil Discovery

Most of the tracks and footprints found in the Cretaceous portion of the Dinosaur Ridge strata represent a wet, lowland, coastal landscape.  However, the dromaeosaurid tracks are located in a bed which is around five million years older than the majority of the footprints and tracks found at this locality.

Commenting on the significance of this Dr Lockley stated:

“A few million years is a long time in evolution and plenty of time for changes in the ancient environment and ecosystem.  The discovery of these raptor tracks demonstrate the substantial changes in the Cretaceous landscapes in North America over time.”

Thylacoleo carnifex Behaviour Deduced from Cave Claw Mark Study

Don’t climb a tree in a bid to avoid an attack from a Marsupial Lion (Thylacoleo carnifex).  That might have proved very good advice to the first inhabitants of Australia who set foot on the continent some 50,000 years ago.  These early explorers would have encountered a bizarre and unique fauna dominated by giant monitor lizards, flightless birds and strange mammals, the like of which existed nowhere else on Earth.

Thylacoleo carnifex

One of the more peculiar creatures, and an animal probably best given a wide berth, was the leopard sized Marsupial Lion (T. carnifex).  The name “Marsupial Lion” for an animal about the size of a male African leopard (Panthera pardus pardus), albeit slightly heavier, may sound like a bit of a misnomer, but from a palaeontological perspective this is just one of the peculiarities surrounding this enigmatic creature.

Thylacoleo carnifex – Study Suggests These Marsupials were Capable Climbers

Capable of climbing trees.

Picture credit: Peter Trusler/Australian Post

However, a new study assessing scratches and claw marks left in the main cavern of Tight Entrance Cave, located in south-western Australia, has provided fresh insights into the likely behaviour and habits of these prehistoric animals.  This new research suggests that Thylacoleo carnifex was an able climber and that it probably raised its young in caves.

A Chequered History

The habits and diet of the Marsupial Lion has puzzled scientists, almost since the initial scientific description by Richard Owen (later Sir Richard Owen), in 1859.  At first, this animal was thought to be a carnivore, but as a member of the Order Diprotodontia along with kangaroos, it was then suggested to have been herbivorous.

Anatomical analysis reveals Thylacoleo to be a robust animal with strong back legs and powerful shoulders, not particularly adept at running.  It had been thought that this animal filled the ecological niche occupied by bears outside Australia.  Recently, the idea that the Marsupial Lion was an apex predator that could drag prey up into trees became popularised.  Thylacoleo as a sort of Aussie version of a leopard was even illustrated on the front cover the prestigious magazine Prehistoric Times.

Prehistoric Times Featured Thylacoleo (Issue 85)

The front cover features a Marsupial Lion.

Picture credit: Prehistoric Times

A Tree Climber?

Scientists from Flinders University (South Australia) analysed the scratch marks left on the walls of the main chamber in the Tight Entrance Cave.  The majority of these marks were clustered on a near-vertical rock face that led up towards an exit to the surface.  That exit may be blocked today, but clearly this way out of the cave was a preferred route for many Marsupial Lions rather than using a circuitous path with a lesser gradient.

This suggests that these animals were confident and assured climbers and remarkably agile.  In addition, the study indicates that the scratches were mostly made by juveniles, this suggests that Marsupial Lions may have reared their young inside caves.

One of the authors of the research, published in the open access journal “Scientific Reports”, Associate Professor Gavin Prideaux (School of Biological Sciences, Flinders University) commented:

“Our findings indicate the Marsupial Lions were running up and down these rock piles to get out of the cave, and they weren’t using the lower-gradient, longer route.  We can be confident now and say that they could climb and if they could climb really well in the dark, underground, there’s no reason they couldn’t climb trees.”

Marks Made by Juvenile Marsupial Lions

In order to confirm that the scratches were most probably made by juvenile Marsupial Lions, co-author Samuel Arman, established a list of seven potential candidates, composed of both living and extinct species.  A model was made of a Thylacoleo paw to test how the digit and claw configuration matched against the scratch marks from the cave.  To assess the sort of claw marks made by extant animals included in the study (possums, wombats and Tasmanian devils), scratch pads were given to zoos so that they could be placed inside the enclosures where these animals were housed.  Any claw markings were examined and cross referenced against the trace fossils from the cave.

Examples of Scratch Marks from the Cave

Claw marks from the cave made (most probably) by juvenile Marsupial Lions.

Picture credit: Flinders University/Scientific Reports

The picture above shows (a) cave wall south, (b) marks from a central rock pile to the west, (c) marks from a central rock pile from the south sub-region of the main cavern, (d and e) scratches from the boulder sub-region.  Scale bar = 10 cm.

Based on this research, it seems that climbing a tree to avoid the attentions of Thylacoleo would not have been a very good idea.

The Ubiquitous Marsupial

The various eclectic theories regarding the habits of T. carnifex that have been proposed may have had something to do with the wealth of fossil material available to study.  More complete or partial skeletons of Marsupial Lions are known from cave sites than for any other extinct Pleistocene species.  Thylacoleo carnifex is amongst the best represented large carnivores known from Pleistocene fossil bearing sites.

For models and replicas of prehistoric mammals: CollectA Deluxe Prehistoric Life.

Rich Fossil Pickings from Gujarat State

Since the turn of the year, Everything Dinosaur has been receiving reports circulated by various Indian universities of further dinosaur fossil discoveries from Kutch district from the state of Gujarat (western India).  In a collaboration with German scientists from the Friedrich-Alexander University of Erlangen-Nürnberg, Bavaria (southern Germany), field team members from the Department of Geology (Kutch University, Gujarat) and Rajasthan University have uncovered the fragmentary remains of a number of dinosaurs and they have identified around 150 sites which may yield yet more fossil data.

Dinosaur Fossils

The latest discovery includes cranial material, excavated from a location close to Lodai village (Kas Hill).  Lodai village itself is located around fifteen miles north-east of the large town of Bhuj

On January 19th, field team members uncovered fragments from the hip bones of a substantial plant-eating dinosaur.  In addition, a partial leg bone was discovered.  The pieces of bone have been tentatively assigned to the Camarasaurus genus and they may represent some of the oldest dinosaur fossils ever found in India.    The fossil material has been dispatched to the Friedrich-Alexander University so that the specimens can undergo radiocarbon dating in a bid to determine an accurate age of the fossils.  Preliminary dating work suggests that the bones are at least 135 million years old (Valanginian faunal stage of the Early Cretaceous).

Sauropod Dinosaur Fossils

Estimating that these bones came from a sauropod (long-necked) dinosaur measuring around fifteen metres in length, Dr Dhirendra Pandey (University of Rajasthan), explained that such fossils provided information on the mega fauna that inhabited this part of the giant, super-continent of Gondwana.  Most of the dinosaur fossils from Gujarat State come rock strata that is actually much younger, dating from the Late Cretaceous.

A Sauropod Dinosaur Exhibit in a Museum

A sauropod (diplodocid) skeleton exhibit on display at the Frankfurt Natural History Museum (Naturmuseum Senckenberg). Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

For models and replicas of sauropods and other dinosaurs: Mojo Fun Prehistoric and Extinct Figures.

Commenting on the new discovery, Gaurav Chauhan, from the Geology Department of Kutch University stated:

“The new fossils include skull, jaw and some teeth of a dinosaur.  We still have to excavate a lot of material in order to get the fossils out.”

Hopeful to Find More Fossil Material

The team are hopeful that more fossil material may be found at this location and that the fossils may represent a new species.

A number of important dinosaur fossil finds have already been reported from this part of India.  For example, back in 2010, Everything Dinosaur reported on the remarkable discovery of a titanosaur nest site, which included the remains of a primitive snake that had died whilst attempting to raid a nest.

To read an article about this remarkable fossil find: Baby Dinosaurs Attacked by Snake.