Endothermic Dinosaurs with a High Metabolic Rate (Except Sauropods)

Scientists have debated whether the Dinosauria were warm-blooded like mammals and birds (endothermic) or cold-blooded (ectothermic) like extant reptiles for over one hundred and thirty years.  A number of papers have been published recently which have added to the immense amount of data compiled as palaeontologists strive to determine just how the dinosaurs dominated life on Earth for much of the Mesozoic.  A team of international scientists have completed a study into the histology (growth) of the thigh bones of modern mammals and their results suggest that some of the dinosaurs may well have been endothermic.

The Dinosauria

The idea of dinosaurs being slow, ponderous, dim-witted beasts has largely been refuted.  The debate over cold-bloodedness versus warm-bloodedness, started by the likes of Huxley and Seeley in the 19th Century was ignited once again with gusto by the American palaeontologist John Ostrom who published a description of the theropod Deinonychus in 1969.  Ostrom depicted Deinonychus as an agile, fast-running predator, a new interpretation of the Dinosaurs as animals which were as active as birds and mammals.

Deinonychus – Surely Not Cold-Blooded?

Fast-running, active, warm-blooded dinosaurs.

Picture credit: Everything Dinosaur

Adding to this debate, a team of scientists from Spain and Norway analysed the thigh bones (femurs) of over one hundred mammals from various habitats in a bid to see if the histology (growth) of these bones provided any indication as to whether the dinosaurs may have been warm-blooded just like the mammals.  Large ruminants were chosen for the study and the research team examined the internal structure of animal’s bones from northern latitudes as well as from temperate climatic zones and the tropics.  Ruminants such as the Muntjac deer, a native of South East Asia and reindeer from northern Svalbard (the most northerly part of Norwegian territory) were included in the extensive study.

The researchers were looking for patterns in the internal structure of the bone that indicated rapid growth as opposed to no growth or very slow growth.  Just like growth rings in trees, the internal structure of a bone can indicate the rate of growth of the bone and consequently the animal to which the bone belonged.  The scientists examined the bones looking for “lines of arrested growth”, otherwise known by the acronym of LAGs.

LAGs are seen in bone sections as dark rings, similar to those seen in tree trunks by dendrochronologists.  The rings are formed, both in the studied mammals and in trees, during the unfavourable seasons (winter or dry season) when the growth of the organism is arrested as a result of a lack of resources.  The presence of LAGs in bones was, until now, considered to be the clearest indicator of ectothermy (cold-bloodedness) since the seasonal arrest of growth was related to the animal’s inability to maintain a more or less constant body temperature (endothermy) during the season of scarce resources.

The Internal Structure of a Mammal’s Bone Showing LAGs

Dark Bands indicate LAGs.

Picture credit: Meike Köhler

The picture above is a slide showing a cross-section of Alpine Red Deer bone.  The two dark bands represent lines of arrested growth.  These patterns in the bones of mammals are similar to those found in many fossilised bones of dinosaurs.  This suggests that if warm-blooded mammals have these bone patterns and many dinosaurs show the same histology, then the dinosaurs may have been endothermic too.

One of the authors of the paper, Meike Köhler (Catalan Institute of Palaeontology, Spain) stated:

“The argument we are giving in our paper, rather in favour of endothermy in dinosaurs, is that between the growth and rest lines, there’s always a big region of highly vascularised (infiltrated with blood vessels) tissue that indicates very high growth rates.  This is typical in dinosaurs and very different from reptiles, which have slow growth between the rest lines.”

LAGs have been found in the bones of extant reptiles and amphibians and it had been assumed that this was evidence of being cold-blooded, organisms not able to control the body temperatures internally but relying on external factors such as the sun to warm them up and keep them active.  Animals that are ectothermic are  more likely to be less able to cope with harsh, cold climates.  However, dinosaur fossil discoveries in such extreme environments as Alaska and near to the South Pole, which although much warmer at the time of the Dinosauria then they are today, would still have been very cold, does suggest that at least some types of dinosaurs were endothermic.

The research team, whose work has been published in the journal “Nature” suggest that such LAGs have been found in many different types of dinosaur.  The only ones without such evidence of warm-bloodedness are the super-sized Sauropoda, animals such as Diplodocus and Jobaria.

In June of last year, Everything Dinosaur reported on research carried out by a team of American scientists who after a study of the teeth of sauropods, suggested that these animals too may well have had a high, internal body temperature, that they were able to regulate themselves without the assistance of external heat sources.  This particular research may not be definitive proof that animals such as Camarasaurus (a North American sauropod), were endothermic as the sheer bulk of these animals with their high volume to skin surface area ratios may have enabled them to maintain a high body temperature.

Contrasting her team’s work with the American study, Meike stated that the sauropods  might have been big enough for their own body mass to generate heat, what the researchers call a “gigantotherm.”

To read more about the American study: Warm-blooded Sauropods?

Researchers don’t know what their growth lines would have looked like, since no animals alive today are gigantotherms. As with most matters relating to sauropod physiology and anatomy, there are no living animals resembling anything like these huge animals alive today, so direct comparisons with extant organisms is very difficult.

The Spanish and Norwegian researchers did not originally set out to provide evidence for support of endothermy in the Dinosauria, this was one of the first times such a systematic study of large mammals had been carried out and the link with the dinosaurs was not the team’s first scientific objective.  Their research is helping scientists to understand how large mammals can cope with extreme climate conditions and how climate change may affect large animal populations.

For examples of very cuddly soft toy dinosaurs: Prehistoric Plush – Soft Toy Dinosaurs.

Dr Köhler went onto add:

“These lines of arrested growth have been used a lot in dinosaurs, but nobody has ever had a really deep look at mammals.”

The debate over whether or not dinosaurs were warm-blooded or not is set to continue.  There is certainly substantial evidence to suggest that dinosaurs were indeed very active and most likely warm-blooded, but animals with high metabolic rates need strong lungs to provide muscles with oxygen to fuel muscles, with no dinosaurs around today understanding their physiology becomes much more difficult.

For another article highlighting this debate: “Clumped Isotopes” provide evidence of Endothermy in the Dinosauria.

Melbourne Fossil Discovery Hints at Rich and Diverse Ecosystem in Australia’s Past

Museum Victoria palaeontologist Dr Erich Fitzgerald has discovered the first Australian fossils of bizarre bony-toothed birds – extinct giants with five metre wingspans.  The five-million-year-old bone of Pelagornis is a new element in an extraordinary fossil fauna uncovered in Melbourne.

Giant “Toothed” Birds

Published today in the Journal of Vertebrate Palaeontology, this important discovery is the first evidence that these gigantic prehistoric birds once soared the skies of coastal Australia.  The Pelagornithidae family, commonly known as bony-toothed birds due to their tooth-like projections on their beak, had wingspans of over five metres.  The species discovered in Australia, Pelagornis, was one of the largest flying animals to exist on Earth after the extinction of pterosaurs 66 million years ago.

Senior Curator of Vertebrate Palaeontology at the Museum Victoria, Dr Erich Fitzgerald stated:

“Bony-toothed birds are enigmatic extinct seabirds with a long history spanning over 50 million years.  They were previously known from all continents except Australia.  The fact that they existed in Australia not that long ago changes our understanding of the evolution of seabirds in this part of the world.”

Dr Fitzgerald and the Fossilised Pelagornis Bone

Five-million-year-old giant bird fossil.

Picture credit: Museum Victoria / Photographer: Jon Augier

The fossil leg bone found in Beaumaris Bay (South Australia) not only provides evidence that these bony-toothed birds were globally distributed, but also offers new insight into the diverse marine life in our seas at the time.  The tooth-like structures in the jaws are not true teeth, but serrations of the beak itself that permitted these birds to catch and hold fish and cephalopods such as squid in their beaks.

Dr Fitzgerald went onto explain:

“We knew next to nothing about the evolution of seabirds in Australia.  This finding shows us that there has been a significant change in seabird diversity between five million years ago and now.  Pelagornis is just one of Victoria’s long-lost marine megafauna, which included bus-sized sharks, giant penguins, killer sperm whales and dugongs.  Life was larger back then!”

According to the co-author on the paper, Mr Travis Park, Honours student at Museum Victoria and Deakin University, “the extinction of these diverse large sea creatures was perhaps linked to long-term changes in their environment.”

Pliocene Terror

Pliocene Terror – Giant “Toothed” Sea Birds

Pelagornis in flight.

Picture credit: Museum Victoria / Artist: Peter Trusler

Travis added:

“The current coastal seas off southeast Australia are less nutrient-rich than previously, and therefore no longer support as many large marine animals.”

Although this fossil discovery shows how much there is still to learn about the evolution and extinction, of these strange giant birds, this research gives us a glimpse into a time when southern Australian sea life was more spectacular than at present.

To read about the discovery of more giant Pelagornis fossils from the Southern Hemisphere (Chile) click the link below:

More Pelagornis fossils discovered: Bird with a “Toothy Grin”.

A Close up of the Vicious “Toothed Beak” of Pelagornis

A very toothy beak.

Picture credit: Museum Victoria / Artist: Peter Trusler

Scale bar in picture = 10 cm

Everything Dinosaur is grateful to Museums Victoria for their help in compiling this article.

Visit Everything Dinosaur’s website to purchase models of prehistoric animals: Prehistoric Animal Figures and Scale Models of Dinosaurs.

Trackways Provide Palaeontologists with an Insight into Alaskan Dinosaurs

The remote Wrangell mountain range of eastern Alaska is proving to be a happy hunting ground for palaeontologists as they strive to find out about the dinosaurs that once roamed these high latitudes.   During the Late Cretaceous, this part of Alaska, which is now an area of rugged mountains built up as a result of extensive vulcanism, was much warmer than it is today, although it was much nearer to the North Pole.  The habitat consisted of dense conifer forests with an understorey of hardy flowering plants and ferns.  These forests were home to a number of dinosaur species as well as many seasonal migrants that came north to graze on the vegetation during the long summer days.  With nearly four months of near total darkness and temperatures dropping to well below zero degrees Celsius, scientists had thought that the onset of winter would have led to conditions that the dinosaurs, as reptiles, could not tolerate.  However, thanks to the discovery of extensive dinosaur tracks, palaeontologists are beginning to build up a picture of a vibrant ecosystem which featured both indigenous and dinosaur seasonal migrants.

Dinosaur Tracks

Tony Fiorillo, a dinosaur expert with the Museum of Nature and Science (Dallas, Texas), has visited these mountains on numerous occasions and during these field trips he has been able to find a number of exciting vertebrate fossil specimens.  His latest catalogued discoveries include fossilised footprints of two different types of dinosaur, the fossils being discovered near the small town of Chisana in the Wrangell mountain range.

Whilst exploring a fossiliferous stream bed in the St. Elias National Park, with Thomas Adams of San Antonio College, Yoshitsugu Kobayashi of Hokkaido University and Linda Stromquist of the National Park Service back in 2008, Mr Fiorillo found a plate-sized rock that contained the clearly visible imprint of the middle toe of a large three-toed dinosaur.  By squinting at the rock and holding it at different angles, he was able to make out the rest of the footprint.  Nearby he found a second dinosaur track, this time the footprint of a much smaller, lighter animal.  The tracks have been identified as belonging to a duck-billed dinosaur, otherwise known as a hadrosaur.  The smaller track would have have been made by a theropod (likely to be meat-eating dinosaur or possibly an ornithomimid).

These prints are the first evidence of dinosaur tracks to have been found in this part of the Wrangell Mountains.

Pictures and Line Drawings of the Dinosaur Prints

Seventy-million-year-old dinosaur footprints.

Picture credit: Tony Fiorillo

Hadrosaur Tracks

The hadrosaur tracks are similar to those discovered in other parts of Alaska.  Palaeontologists have postulated that large herds of these plant-eating dinosaurs migrated northwards each year to take advantage of the lush vegetation and the almost 24-hours of daylight in the summer months, permitting rapid plant growth.

Following the herds would have been predatory dinosaurs, such as tyrannosaurs.  The smaller track-way may represent that of an indigenous carnivore, an animal that lived in the Alaskan region all year round but relied on the bounty of scavenging the kills of bigger dinosaurs to see it through the harder winter months.

Mr Fiorillo, described the smaller dinosaur:

“This little guy ran around on two legs, might have been six feet from snout to tail and had a bunch of little pointy teeth and sharp claws.  He was eating meat, but there was a lot of this ecosystem we didn’t pick up (fossils that would indicate what the dinosaur as tall as a small child was eating).”

Palaeontologists know that troodontids lived in this part of the world during the Late Cretaceous, these small, light predators grew to lengths in excess of four metres and weighed perhaps as much as 100 kilogrammes, but the tracks are not representative of a troodontid.  Troodontids run on only two toes and these prints definitely show a three-toed animal walking on all of its toes.

Mr. Fiorillo and his co-dinosaur hunters are looking forward to returning to the location in future, so they can find more evidence of the region’s Late Cretaceous inhabitants.

For models and scale replicas of theropod dinosaurs and hadrosaurs: Theropod and Hadrosaur Models (CollectA Deluxe Figures).

U.S. Government Steps In to Seize Tyrannosaur Fossil in New York

As reported by Everything Dinosaur in previous blog posts, U.S. customs officials have seized the Tarbosaurus fossil that had been controversially sold at auction last month.  Yesterday, representatives of the U.S. government seized the fossils of the tyrannosaur, removing the crates in which they were stored to a secret location.  This is probably the first step in what will be a fairly drawn out process that will end with the fossil material being returned to Mongolia, where the fossils originated from.

Tarbosaurus Fossil

Palaeontologists having examined the Tarbosaurus bataar fossils have declared that the specimen was probably collected illegally between the years 1995 and 2005 and then smuggled out of Mongolia.  The eight-metre-long, mounted specimen was sold at auction last month for a sum over one million USD.

The seizure was ordered by a federal judge in Manhattan earlier this week, and on Friday wooden crates holding pieces of the fossil were loaded onto a truck at a Queens storage centre and driven away to an undisclosed location where the remains of this Late Cretaceous predator will be held pending further developments.

In a written statement, the President of Mongolia, Elbegdorj Tsakhia, who had personally intervened to try to prevent the auction back on May 20th commented:

“We are one step closer to bringing this rare tyrannosaur skeleton back home to the people of Mongolia.”

The fossil had been stored at the Cadogan Tate Fine Art gallery, photographs of the removal by U.S. officials were taken by Houston lawyer, Robert Painter, who had been acting on behalf of the Mongolian government in this case.

In a written statement, those responsible for challenging the original auction sale commented:

“Today we send a message to looters all over the world, we will not turn a blind eye to the market place of looted fossils.”

Bolortsetseg Minjin, Director of the Institute for the Study of Mongolian Dinosaurs, took pictures of the removal of the crates as well, saying:

“It’s a very exciting event.  It’s just unbelievable.  I never expected it would be this fast.”

Illegal Removal from Mongolia

Although team members at Everything Dinosaur, signed a petition to prevent the actual auction, the sale itself is not at the centre of this dispute.  It has been illegal to remove fossils from Mongolia for more than fifty years and the arguments concerned whether the fossil had been smuggled out of Mongolia.  The United States had requested the seizure in a lawsuit, stating that the relics had been brought into the USA with documents that disguised the potentially valuable dinosaur skeleton and misrepresented what was actually being imported.

Eric Prokopi, 37, of Gainesville, Florida, the person responsible for bringing the fossils into the States, defended his handling of the skeleton in a written statement on Thursday, saying that he was not an international smuggler and that he had worked since bringing the bones into the country in March 2010 to turn chunks of rocks and broken bones “into an impressive skeleton”.

Mr Prokopi said in a statement:

“I can wholeheartedly say the import documents are not fraudulent, a truth I am confident will be brought to light in the coming weeks.”

When asked to explain the discrepancy between the stated value on the import documentation when compared to the auction sale price, Mr Prokopi added:

“The value was declared much lower than the auction value because, quite simply, it was loose, mostly broken bones and rocks with embedded bones.  It was not what you see today, a virtually complete, mounted skeleton.”

The bones were valued on the importation documents at only $15,000 USD, but the skeleton Prokopi prepared and put together that was sold at the New York auction last month fetched $1.052 million USD.  The sale is contingent on the outcome of  litigation involving the dinosaur fossil material.

Although the buyer has not been officially disclosed, Painter said he had been informed that a New York based private gallery owner had made the winning bid at the auction.

We at Everything Dinosaur, hope that this situation is soon resolved.  With luck, the fossils will be returned to Mongolia where they can be studied by scientists from the Institute for the Study of Mongolian Dinosaurs, alongside other Tarbosaurus material.  Once a more formal study has been made, it might be possible to put the fossils of this Late Cretaceous predator on display so that the people of  Mongolia can view an example of their very own tyrannosaur.

For models and replicas of Tarbosaurus and other tyrannosaurids: Tyrannosaurs and Dinosaur Models (PNSO).

Evidence of Dairy Farmers from Prehistoric Libya

A team of international researchers have published a paper in the scientific journal “Nature” detailing the evidence suggesting that humans were domesticating cattle and using their milk as early as seven thousand years ago.  The scientists, led by researchers from the University of Bristol (United Kingdom), analysed fatty acids that had been extracted from fragments of unglazed pottery from an archaeological dig site in Libya.  The study showed that dairy fats were processed in the containers.

Prehistoric Libya

This research is strong evidence that dairying practices were being carried out by Neolithic people living in the Saharan area of Africa as early as the fifth millennium B.C.  Ten thousand years ago, the Sahara Desert area was a lush paradise with abundant game.  Early hunter-gatherer peoples living in the area had a semi-sedentary lifestyle, making pottery, hunting wild animals and collecting wild plants such as cereals.  As the area became more arid, in the period of time between 7,000 and 5,000 years ago the inhabitants of the region adopted a more nomadic way of life, as indicated by the discovery of many cattle bones in cave deposits and by sites of Neolithic camps.

Domesticated animals were clearly significant to these people: the engraved and painted rock art found widely across the region includes many vivid representations of animals, particularly cattle.  However, no direct proof that these cattle were milked existed – until this new research.

Researchers at the Organic Geochemistry Unit in Bristol’s School of Chemistry, with colleagues at Sapienza, University of Rome, (Italy) studied unglazed pottery dating from around 7,000 years ago, found at the Takarkori rock shelter in the Tadrart Acacus Mountains, Libya.

Using lipid biomarker and stable carbon isotope analysis, they examined preserved fatty acids held within the fabric of the pottery and found that half of the vessels had been used for processing dairy fats.  This confirms for the first time the early presence of domesticated cattle in the region and the importance of milk to its prehistoric pastoral people.

Ancient Dairy Farmers

One of the authors of the paper, PhD student at Bristol’s School of Chemistry, Julie Dunne commented:

“We already know how important dairy products such as milk, cheese, yoghurt and butter, which can be repeatedly extracted from an animal throughout its lifetime, were to the people of Neolithic Europe, so it’s exciting to find proof that they were also significant in the lives of the prehistoric people of Africa.”

The student went on to add:

“As well as identifying the early adoption of dairying practices in Saharan Africa, these results also provide a background for our understanding of the evolution of the lactase persistence gene which seems to have arisen once prehistoric people started consuming milk products.”

Not all Neolithic or indeed Bronze Age people were lactose tolerant, able to consume dairy products.  A new analysis of the genome of “Oetzi” – The Iceman, a frozen 5,300 year-old mummy found in the Alps suggests that this particular European was lactose intolerant.

To read more about this new genetic study of the ice mummy: “Oetzi” – The Iceman – New Genome Study Reveals More Secrets.

Commenting on the presence or absence of a lactose tolerant gene within early human populations a spokesperson for the research team stated:

“The gene is found in Europeans and across some Central African groups, thus supporting arguments for the movement of people, together with their cattle, from the Near East into eastern African in the early to middle Holocene, around 8,000 years ago.”

Explaining the problems that had been encountered when trying to accurately calculate when dairying was first practiced, Co-author Professor Richard Evershed (Bristol University’s School of Chemistry) added:

“While the remarkable rock art of Saharan Africa contains many representations of cattle – including, in a few cases, depictions of the actual milking of a cow – it can rarely be reliably dated.  Also, the scarcity of cattle bones in archaeological sites makes it impossible to ascertain herd structures, thereby preventing interpretations of whether dairying was practiced.”

Isotope Analysis

However, molecular and isotopic analysis of absorbed food residues in pottery is a reliable way to investigate the diet of and agricultural practices of early humans.  Scientists have used similar methods to determine the adoption of other farming methods in the Near East and their spread westwards into Europe.

It seems that as far back as seven thousand years ago, in the area that was to become the country of Libya, some people were milking cows.  It is not sure whether this work would have been carried out by the menfolk or left to the women.  The cave art that depicts milking scenes does not provide strong evidence either way.

Visit Everything Dinosaur’s website for dinosaur toys and prehistoric animal themed gifts: Prehistoric Animal Figures and Models.

U.S. Immigration and Customs Expected to Act on Friday (22nd June)

The mounted skeleton of an Asian cousin of Tyrannosaurus rex is expected to be seized by U.S. Custom officials tomorrow as the international legal dispute over the rightful ownership of this fossil specimen continues.  The eight-metre-long, mounted skeleton of a Tarbosaurus bataar was auctioned in New York last month, it fetched over £630,000 GBP when it went under the hammer, but from the day the auction lot was announced it has attracted controversy.

Tarbosaurus bataar

To read about the T. bataar fossil coming up for auction: Tyrannosaurid Up for Auction.

A team of palaeontologists from North America and Mongolia examined the specimen after the sale, once a court order had been put in place to prevent the movement of the specimen to the private individual who had bid the highest at the New York based auction.  These experts declared that the fossils had originated from Mongolia, most probably the Nemegt Formation where a number of Tarbosaurus fossils have been discovered.  It has been illegal for more than fifty years to excavate and take fossils out of Mongolia and it is suspected that this particular specimen was collected by poachers and smuggled out of the country.

To read more about the palaeontologist’s study of the Tarbosaurus remains: Experts state that Tarbosaurus fossils definitely smuggled out of Mongolia.

The Tarbosaurus Specimen Under Investigation

Going nowhere- Mounted skeleton set to be seized by customs officials.

Picture credit: Reuters/Heritage Auctions

When team members at Everything Dinosaur were first informed about the intended auction, they signed an on-line petition to help stop the sale taking place, as they were aware that it had been against the law in Mongolia to export such specimens.  Now a warrant that allows U.S. officials to seize the fossil has been signed by a New York based federal judge.

Commenting on the case, Luis Martinez, a spokes person for the U.S. Immigration and Customs stated:

“We should have it by the end of the week.”

The government of Mongolia will no doubt, welcome this move, prior to the auction the Mongolian President personally intervened to try to stop the sale.  Mongolia is claiming sovereign ownership of the T. bataar specimen and wanting the fossils returned to Mongolia.

Mongolian Government Request

At the request of the Mongolian government, a U.S. District judge in Dallas (Texas) issued a restraining order preventing the skeleton from being moved or the ownership transferred while the dispute continued.  Manhattan U.S. Attorney Preet Bharara filed a lawsuit on Monday seeking the forfeiture of the nearly intact skeleton and its return to the Mongolian government.

In New York, U.S. District Judge Kevin Castel on Tuesday issued an order to seize the fossil, ruling there was probable cause it was subject to forfeiture under federal laws due to false claims made regarding the value of the imported item into the USA from the United Kingdom and other infringements concerning the customs paperwork.

A spokesperson stated:

“From a legal standpoint, the U.S. government’s lawsuit shifts the burden of proof from Mongolia to Heritage [Heritage Auctions who organised the original sale in New York] and others who might make a claim to its ownership.”

Heritage Auction officials have stressed from the beginning that they would cooperate with authorities, keen to avoid any adverse publicity and any legal ramifications for their part in the sale.  The company maintains that the fossil was legally obtained and brought to auction by a reputable consignor.

Jim Halperin, Co-chairman of Heritage Auctions said in a statement:

“We believe our consignor purchased fossils in good faith, then spent a year of his life and considerable expense identifying, restoring, mounting and preparing what had previously been a much less valuable matrix of unassembled, underlying bones and bone fragments.  We sincerely hope there is a just and fair outcome for all parties.”

U.S. federal officials claim that the smugglers made false statements about the skeleton when it was imported into the United States from the UK in 2010.  The skeleton did not originate in Britain nor was its value only $15,000  (£10,000) as claimed, the officials assert.

Mongolia has has strict laws in place for five decades regarding the excavation, removal and shipment of fossils and other rare artefacts from the country.  Such items are considered property of the Mongolian government.  It is likely that this fossil specimen was removed from Mongolia between 1995 and 2005 according to the palaeontologists who examined the Tarbosaurus.

We expect this dispute to rumble on, but hopefully action taken by the U.S. authorities will serve as a deterrent and prevent the smuggling of other specimens out of Asia for sale in the West.

To view models of Tarbosaurus (whilst stocks last): Theropods and Dinosaur Figures (PNSO).