All about dinosaurs, fossils and prehistoric animals by Everything Dinosaur team members.
10 04, 2008

Definition of the Term Lagerstätte

By |2022-11-14T11:35:25+00:00April 10th, 2008|Geology, Palaeontological articles|0 Comments

The Term Lagerstätte Defined

Readers of books about fossils and dinosaur discoveries may come across the term “Lagerstätte”.  In answer to a number of questions received by Everything Dinosaur blog visitors, team members will briefly outline what the term Lagerstätte means. We will define Lagerstätte.

Lagerstätte

This is a German phrase from the words Lager (which means storage) and Stätte (which means place).  It refers to a deposit of sedimentary strata that contains a lot of fossil material that is exceptionally well preserved.  There are a number of Lagerstätten (plural) known, from the famous Burgess Shale deposits of British Columbia, the Mazon Creek Formation (Carboniferous strata) in Illinois, the Jurassic Solnhofen limestone deposits from southern Germany and the Cretaceous fossil deposits of the Liaoning and Hebei Provinces of north-eastern China.

Typical Fossils from a “Lagerstätte”

Some belemnite guard fossils, the coin shows scale.

Belemnite guard fossils from the “Jurassic Coast”.

Picture credit: Everything Dinosaur

A Phrase for Every Occasion

The German language seems to have a word for just about everything, a phrase for every occasion. Perhaps, it has more scope and depth than English, we at Everything Dinosaur are probably not best placed to comment as we would not call ourselves experts on European languages. Could English lack certain broad and all-inclusive linguistic qualities that other languages seem to possess? We hope that we don’t sound upset over the inadequacies of our native tongue, no sense of “schadenfreude” from us.

Lyme Regis on the Dorset Coast – An Example of a Lagerstätte

Prospecting for fossils (Lyme Regis) - Lagerstätte.

Looking for fossils at Lyme Regis. The marine deposits date from the Lower Jurassic along this stretch of the Dorset coast and the strata is typical of a Lagerstätte. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Everything Dinosaur stocks a range of replicas of iconic fossil animals known from the extensive fossil record of the Dorset “Jurassic Coast”. The range includes models of belemnites, nautiloids and ammonites.

To view this range: Replicas of Fossil Animals Including Dinosaur Teeth.

9 04, 2008

The Tooth, the whole Tooth and nothing but the Tooth (Mammals)

By |2023-02-24T21:45:00+00:00April 9th, 2008|Dinosaur and Prehistoric Animal News Stories, Main Page|0 Comments

Teeth in Mammals hold the Key to Identification

Mammals have been around for approximately 210 million years, the fossil record indicates that they first appeared in the Late Triassic.  Admittedly, mammals of the Mesozoic were small, many of them were shrew-like creatures, filling the niches not exploited by the dominant reptiles.  It has been speculated that many of them were nocturnal and that they lived inconspicuously in burrows or rock crevices keeping out of the way of the larger terrestrial reptile groups.  Mammal teeth fossils can play a key role in identification and taxonomy.

The Age of Mammals

Following the mass extinction event that ended the Mesozoic era and heralded the start of the Cenozoic, the diversity of reptiles never recovered.  Instead in the animal kingdom the mammals, birds and insects seemed to have rapidly evolved to exploit the new environments and ecological niches opened up by the mass extinction.  In the plant kingdom the angiosperms (flowering plants) continued to go from strength to strength dominating plant life on Earth.  The naming of the Cenozoic is appropriate as translated from the Greek the word means “new life”.

The evolutionary relationships between different types of mammals is unclear, the paucity of the fossil record accounts for this.  Indeed, mammals may have been more common in the Jurassic and Cretaceous than is indicated by the fossil evidence, but the poor preservation potential of these animals limits the amount of fossil specimens likely to be found.

Mammals would have had a limited preservation potential as being small any carcases would soon have been scavenged and the relatively tiny, delicate bones would have been unlikely to survive the fossilisation process.  Inhabiting environments such as deserts, scrubland and woodland would have limited the opportunities for fossilisation even further (these environments are not conducive to fossil forming conditions in normal circumstances).

Mammal Teeth

However, teeth made from enamel, the hardest substance in the body, can survive fossilisation and even though mammal teeth fossils are exceptionally rare they can provide vital information as to the appearance of the entire animal and what it ate.  Many of the extinct early mammal groups are known only from isolated teeth and fragments of jawbones.  Unlike the simple teeth of reptiles (even dinosaurs had relatively simple teeth compared to mammals), mammalian teeth are differentiated by their shape.  The shape of the teeth dictates their function.

Incisors and canines at the front of the mouth are used for obtaining food and holding on to it.  The cheek teeth, towards the back of the jaw are the food processors, grinding up the food as the first part of the digestion process.

To read more about an example of mammalian teeth from the Mesozoic:

Very Ancient Udders! Mesozoic cow discovered in India.

To learn how such specimens are dated (often dated by matrix and sediment data found in-situ with the main specimen):

Dating the Mesozoic Cow! It was the fish and ostracods that did it.

These cheek teeth, the molars and pre-molars have distinctive patterns of cusps, ridges and furrows which in combination with the movement of the jaws allows for efficient cutting and chewing.  These distinctive teeth, their wear patterns and size can provide palaeontologists with a surprising amount of data.  An entire genus could be described from the evidence of a single fossil tooth.

Teeth in Mammals – A Key to Identification

A close view of the interior of the Eofauna Scientific Research Steppe Mammoth model.  Mammal teeth can help with idenfication.

A close-up view of the mouth of the Steppe Mammoth.  Mammalian fossil teeth can be pivotal in identification.  Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The picture (above) shows a close-up view of the teeth of the Eofauna Steppe Mammoth model, a company with a deserved reputation for producing excellent prehistoric mammal models.

To view the Eofauna model range: Eofauna Scientific Research Models.

Teeth Morphology

Teeth morphology can also help scientists distinguish between different types of mammals such as monotremes, marsupials, placental mammals (extant groups) and the now extinct group the multituberculates.  The multituberculates (named after the multiple cusps or tubercles on their molar teeth), were a relatively successful group of Mesozoic and early Cenozoic mammals.

Fossil evidence has been found in Middle Jurassic strata indicating that they evolved around 160 million years ago.  They were probably nocturnal, herbivorous with a burrowing habit, superficially resembling many of the rodents found today.  Most of the fossil evidence has been gathered in the northern hemisphere it is not clear whether these mammals existed in Gondwanaland.

Multituberculates probably gave birth to very small, under-developed young.  This associates them with Marsupials.  This information has been assumed by studying the relatively few fossils of bones from pelvic area.  In many specimens, the pelvic area is quite narrow and this would make the ability to give birth to larger fully formed young unlikely.  This many group went into steep decline towards the end of the Palaeogene, becoming extinct approximately 35 million years ago.

8 04, 2008

Ancient Harvestman Discovered Preserved in Amber

By |2023-02-25T07:52:22+00:00April 8th, 2008|Dinosaur and Prehistoric Animal News Stories, Main Page|0 Comments

Ancient Arachnid Preserved in Amber

A rare relative of spiders has been discovered preserved in 40 million year old amber.  The little creature was trapped in pine resin and preserved with the resin eventually turning into amber.  This rare specimen identified as a Harvestman (Dicranopalpus ramiger), has been donated to the London Natural History Museum.

The amber, which was from the Baltic area dates from the late Eocene, amber of this age and from the Baltic is fairly common but to find such a rare and complete specimen so well preserved is a very special event.  It seems that around 40 million years ago, a tiny harvestman climbed up a pine trunk, encountered a lump of thick, sticky tree sap and was engulfed.  The whole animal was trapped, a set of events leading to the preservation of this relative of true spiders for scientists to study.

Ancient Harvestman

A Rochester-based fossil collector (Rochester in Kent, England); had purchased a number of amber pieces on an on-line auction website, on receiving the goods, a close examination of the amber revealed a tiny leg hiding in one piece.  He carefully polished it and slowly removed some layers to reveal the complete fossil of this tiny forest inhabitant of the Cenozoic.  Realising he had found something unusual the specimen was sent to the London Natural History museum for expert analysis.

Dr Andrew Ross, Collection Manager of fossil invertebrates and plants at the museum commented:

“when we looked at the amber under the microscope we could see it was a harvestman”.

Harvestmen belong to the arachnid class, the earliest fossil Harvestmen date from the Lower Carboniferous deposits from East Kirkton, Scotland.  A fossil Harvestman from these deposits, an opilonid has been dated to around 320 million years ago, although these creatures may have existed even earlier, perhaps being some of the first creatures to adapt fully to a terrestrial lifestyle.

Today there are around 26 species of Harvestmen in the UK. They may look like spiders with their eight legs but this is only a superficial similarity.  Harvestman have no silk glands, they cannot spin silk, they have not got the ability to defend themselves with a poisonous bite, their only means of defence in most species is to produce a foul smelling chemical to put off a would be attacker.

Different from Spiders

Spiders have a segmented body, with a head, thorax and abdomen clearly divided.  Harvestmen have a fused body with no body segments

“This one is quite a young animal”, explained Dr Ross. “Its body is the size of a pinhead and its legs are about 6 mm long.

“But what is really interesting is that all of its legs are still intact – usually some of the legs will snap off as the creatures try to escape the sticky resin”.

Amber is an important preservation medium, allowing the preservation of small, delicate bodied animals that would not normally be preserved in rock.  This find of a species now extinct helps scientist’s to build up a picture of the ecosystem in those ancient Baltic forests.

For models and replicas of prehistoric animals: Dinosaur and Prehistoric Animal Figures.

7 04, 2008

Deinonychus – a new Interpretation inspired by Ostrom

By |2023-02-25T07:53:40+00:00April 7th, 2008|Dinosaur and Prehistoric Animal News Stories, Main Page|0 Comments

“Terrible Claw” – that was not so Terrible

In 1931, the great American fossil hunter Barnum Brown discovered the bones of a small, agile predatory dinosaur in Wyoming (Western USA).  The animal was named Daptosaurus, it means “active lizard”.  Unfortunately, despite being aware that this was a new genus of dinosaur, Barnum Brown never actually got round to describing this new dinosaur, and as a result Daptosaurus was not recognised by the wider scientific community.

Deinonychus – A New Interpretation

John Ostrom, another American palaeontologist, uncovered more fossilised bones of Daptosaurus in 1964 and he went onto name and describe the animal as Deinonychus in 1969, on year after Barnum Brown had sadly passed away.  So far, something approaching a dozen specimens have been found, including the remains of Deinonychus individuals next to a Tenontosaurus (a large hypsilophodontid herbivore), a rare example of predator and prey being found together.

The work of John Ostrom and other researchers led many scientists to see dinosaurs in a different light.  Instead of being depicted as slow, lethargic cold-blooded reptiles many began to be interpreted as active, agile and bird-like.

Deinonychus remains have been found in Early Cretaceous strata of Montana, Oklahoma and Wyoming.  The animal grew to a length of approximately 3 metres and might have weighed as much as 80 kilogrammes.  The head was 2.5 metres off the ground.   From the group of Deinonychus fossils (and recent trackway evidence), it has been suggested that this animal, a member of the Dromaeosauridae, lived and hunted in packs.

To read more about recent finds of dromaeosaur trackways: Evidence of Pack Behaviour in “Raptors” unearthed in China.

More dromaeosaur trace fossil news: Two-toed footprints found in Korea – Evidence of Dromaeosaurs in Korea.

The second toe of the four on the hind foot did not touch the ground.  Instead it was held aloft as it had the large sickle-shaped claw on the end.  Scientists like Ostrom speculated that this was probably the primary weapon used by this fierce little hunter.  The claw could have been swung forward and used to slash its victims.  However, recent studies by a team from the University of Manchester and other groups has cast some doubt over this hypothesis.  Although the point of the claw was relatively sharp the curved surface of the claw was not so sharp.

The force needed to slash away at the tough hide of a dinosaur would have been immense.  It now seems that this claw may have served more as a grappling hook, allowing a pack of Deinonychus to mob a larger dinosaur, jumping on it using their claws to get a purchase and to help bring the animal down.

An Illustration of Deinonychus (D. antirrhopus)

Picture credit: Everything Dinosaur

Close analysis of the jaws of dromaeosaurs including Deinonychus indicate that they were very strong.  Large muscles positioned towards the rear of the skull indicates that they could be opened very wide (wider than the 70 degrees permitted by the jaws of a lion).  Perhaps the jaws could have opened wide enough to bite down onto the windpipe and suffocate large prey animals – a form of predation favoured by many big cats today.

The Beasts of the Mesozoic range of articulated dinosaur models features several dromaeosaurid dinosaurs.  To view this popular range of collectable dinosaur figures: Beasts of the Mesozoic Dinosaur Figures.

6 04, 2008

Frog Blog Week 4 – Tadpoles Starting to Hatch

By |2023-02-25T08:12:30+00:00April 6th, 2008|Animal News Stories, Educational Activities, Everything Dinosaur News and Updates, Main Page|1 Comment

The Tadpoles have Started to Hatch

Great excitement this week in the pond as the tadpoles have begun to hatch.  The first signs of movement were detected on Wednesday morning.  This was on the 2nd of April, just 17 days after the spawn was laid.  Given the quite cold weather that we had been experiencing we were surprised how quickly the tadpoles developed.  However, it is worth noting that despite the cold weather and the chilly pond water, the spawn had been laid in a central position in the pond and this allowed the spawn to get what sun there was for most of the day.  Also, the jelly swells and becomes buoyant thus permitting the spawn to stay at the surface, again helping to warm the eggs.  Sat on their bed of pond-weed (Elodea) the spawn has been fairly quick to develop.

The Latest Picture of the Frog Spawn

Picture Credit: Everything Dinosaur

Tadpoles Starting to Hatch

By Wednesday lunchtime, team members were taking turns to watch the spawn, every now and then a little tadpole would move slightly, either curling or uncurling.  By Friday the movements had become stronger and more frequent.  The embryos had assumed a more tadpole-like shape and could be seen moving inside the egg membrane.

The first hatchlings were observed on Saturday afternoon (5th April).  The tadpoles have developed a definite head end (a round bulge) and a basic tail.  However, it will be a few days before they are swimming freely.

At this stage, the muscular and circulation systems are developing, the gill arches either side of the head are now forming.  The tadpoles hatch at around the time these gills are able to function.  The eyes and mouth are not fully developed and there is an adhesive organ present on the top of the head.  This permits the tadpole to attach itself to pond weed and remain there until further changes have taken place.

Spotting the External Gills

If you can get close enough and look very carefully at a tadpoles head from the top downwards (called a dorsal view by scientists), you should be able to see two small tiny bumps, one on each side of the head.  These are the external gills and they should be visible for about 12 days or so.  Over this period a fold of skin known as the operculum develops on the first branchial arch just in front of the external gills.  It grows backwards until the external gills are covered.  The eyes and mouth begin to develop.

The operculum does not close up completely, a single hole (called a spiracle) remains on the left side of the body.  Water is taken in through the newly formed mouth, passes over the internal gills and is expelled through this spiracle.  By this time the mouth should have developed definite jaws and the adhesive organ on top of the head should have almost completely disappeared.

The digestive system should have expanded (for the first few days after hatching the tadpoles live on the remains of the yolk from the egg – this can be seen as a bulge in their tummies).  Soon the tadpoles will have acquired the ability to swim and they will have started their journey towards becoming frogs – metamorphosis.

Frog Observed

Only one frog has been observed in the pond during daylight hours.  We think this is a male, it has been seen around the spawn and some of us have jokingly speculated that this might be the “expectant father” waiting for his babies to hatch.  We know that many species of amphibian demonstrate some care for their offspring.  For example, male Midwife toads (Alytes obstetricans) gather up the eggs once they have been fertilised and they carry them around on their back legs, but we are not aware of any paternal instinct being demonstrated by Common Frogs (R. temporaria).

Much of the country has been covered in a blanket of snow, this morning.  Typical of the British weather, no snow in winter and then on the 5th April we get some.  This picture was taken of the area behind the office this morning.

Oh to be in England now that April’s Here!

Picture credit: Everything Dinosaur

5 04, 2008

Review of Pop-up Facts Dinosaurs

By |2023-02-25T08:13:46+00:00April 5th, 2008|Book Reviews, Main Page|0 Comments

Pop-up Facts Dinosaurs (Review)

Time to step back to the Mesozoic (Age of Reptiles) and meet some of the amazing animals the lived during the Triassic, Jurassic and the Cretaceous.

The Front Cover of Pop-Up Facts Dinosaurs

Picture credit: Everything Dinosaur

To view the range of toys, models, learning materials and games available: Visit Everything Dinosaur.

A hardback book that is beautifully illustrated contains lots and lots of facts and information about dinosaurs and other prehistoric animals.  Young readers can wonder at the huge plant-eating sauropods that pop out of the page at you, examine fossil evidence of the colossal meat-eating dinosaurs and study marine reptiles as well as pterosaurs.  Page after page of truly impressive pop-ups, packed with fascinating facts, tabs to pull, flaps to lift and wheels to turn.  Even the front cover which depicts a theropod dinosaur in 3-D relief has a dinosaur eye that looks straight back at the reader.

Recommended for young dinosaur fans aged 5+ a super, dinosaur book, crammed with facts and very educational, this is a great example of a book about dinosaurs for kids.

An Example of the Fact Filled Pop-up Pages

Picture credit: Everything Dinosaur

Visit Everything Dinosaur’s Homepage: Everything Dinosaur.

4 04, 2008

Mammoths in the Cinema

By |2022-11-14T07:35:39+00:00April 4th, 2008|Dinosaur and Prehistoric Animal News Stories, Main Page|0 Comments

Mammoths in the Cinema – 10,000 B.C. and all That

No prehistoric movie or television series seems complete without at least one Mammoth being included.  Now that CGI has come to the fore, depicting these large elephants with their long shaggy fur coats is not too much of a problem.  Although we have been told by technicians and CGI operators that getting the fur to look realistic on screen is quite a challenge, at least with dinosaurs (feathered ones excepted), the computer experts are not encumbered with these skin features and dinosaurs are to some extent a little easier to re-create.

Mammoths in the Cinema

From studies of the exceptionally well preserved Mammoths from Siberia, scientists have a fairly good understanding of how the hair on these creatures looked.  The coat consisted of two basic layers, a coarse outer layer of guard hairs and an undercoat that helped insulate these animals from the cold.  This is a typical adaptation to cold, harsh environments seen in many mammal species, both extinct and extant (around today).

The outer guard hairs were up to six times thicker than human hair and in large specimens some of these hairs grew to over a metre in length.  This outer coat provided effective water-proofing.  The inner coat was made up of thinner, softer and far shorter hairs this coat helped provide insulation and keep out the cold.  The coat colour in Mammoths varies with some dark brown whilst others appear almost reddish/orange in colour.  We have the frozen carcases of Siberian Mammoths to largely thank for providing us with a Mammoth colour chart.

Frozen Mammoth Carcases Provide a Guide to Mammoth Colouration

Mammoth coat colours.

Strawberry blonde Mammoth from Everything Dinosaur.

Picture credit: Everything Dinosaur

The picture (above) shows a model of a Papo juvenile Woolly Mammoth that has been altered digitally to show variation in colour. To view the Papo range: Papo Prehistoric Animal Models.

Many of the models Everything Dinosaur supplies are hand-painted.  Each model has tiny variations which is very appropriate given that the structure and format of every Mammoth’s coat would have been slightly different – just as the hair on our heads is different from person to person.

To see a model of Woolly Mammoth and other prehistoric animal figures: Prehistoric Animal Models.

The degree of hairiness varied with the Mammoth species, Columbian types (Mammuthus columbi) were less hairy than the Woolly types (M. primigenius), perhaps an adaptation to a slightly less harsh climate.  It is likely that Mammoths had a spring moult to produce a lighter summer coat.

Their heavy coats were not their only source of insulation, many Mammoth fossils have revealed a fat layer up to 10 cm thick just below the skin surface.  This would have provided exceptional insulation, an example of adaptation to colder climates and a food store inside the animal to help it overcome leaner times.

3 04, 2008

Man saves Wife from Crocodile

By |2023-02-25T08:14:41+00:00April 3rd, 2008|Animal News Stories, Main Page|0 Comments

Husband saves Wife from a Saltwater Crocodile Attack

A husband and wife had a lucky escape from a crocodile attack in a remote part of the Australian outback.  The couple were swimming in a small creek whilst holidaying in an area 100 miles southwest of Darwin in Australia’s Northern Territory.

Saltwater Crocodile Attack

The attack was from a Saltwater, otherwise known as an Estuarine crocodile (Crocodylus porosus).  These animals are the largest species of crocodile on the planet and the heaviest of all the reptiles around today.  Adult males can reach lengths in excess of 20 feet and weigh up to 1 Tonne.  The largest Estuarine recorded was shot in Sumatra, Indonesia in 1978, it was reputed to be over 28 feet long and weighed more than 1300 kilogrammes.

The woman suffered leg and hand injuries but things could have been much worse had it not been for the bravery of her partner, who jumped on the 8 foot crocodile’s back in the successful rescue.  Acting like a real-life “Crocodile Dundee” the man leaped onto the reptile and this forced the crocodile to let the woman go.

The wife was taken to the Royal Darwin Hospital to have her wounds treated, a spokesman for the hospital commented: “the husband’s very swift and diligent actions have saved the day”.

This is the fourth crocodile incident that has been reported in recent weeks from the Northern Territory.  A few days earlier police were forced to open fire on a crocodile as it closed in on a swimmer who had accepted a dare to swim to an offshore crocodile trap.  A crocodile attacked a boat of tourists in the same area and in January a man rescued his colleague from a crocodile but accidentally shot his unlucky co-worker in the process.  Well, if it is not your day, it’s not your day!

Many parts of the Northern Territories have seen an increase in the number of Saltwater crocodiles, now that hunting has been largely banned.  Unfortunately, these aggressive predators are very capable of attacking people and once above 8 foot in length they are officially classed as man-eaters.  There has been a call for a controlled cull in order to reduce the number of large crocodiles in the area.

To read more about the problems caused by the growing population of Estuarine crocodiles in the Northern Territory: Invasion of the Crocodiles.

2 04, 2008

The Tuatara has a Surprise in its Genes

By |2022-11-14T07:29:22+00:00April 2nd, 2008|Animal News Stories, Main Page|0 Comments

The Tuatara is the fastest-known Evolving Animal

A team of researchers have identified the rare New Zealand Tuatara as the fastest evolving animal yet to be fully studied, at least at the molecular level.

The Tuatara (Sphenodon punctatus) belongs to an otherwise extinct reptilian group called the Rhynchocephalians.  These reptiles are characterised by the presence of a beak-like upper jaw.  Although the origin of this particular group of reptiles can be traced back to the Early Triassic, just one genus (one species) remains today.   To estimate the rate of evolution taking place within a species the research team studied DNA samples taken from ancient Tuatara remains dating from approximately 8,000 years ago and compared them to samples taken from living Tuatara.

New Zealand Tuatara

The scientists found that although these little reptiles have remained largely unchanged physically over very long periods of evolution, they are evolving, at a molecular level faster than any other animal yet examined.

“What we found is that the Tuatara has the highest molecular evolutionary rate that anyone has measured,” commented researcher David Lambert from the Allan Wilson Centre for Molecular Ecology and Evolution in New Zealand.

Many scientists have hypothesised  that molecular evolution would be fastest in animals whose physical form, or morphology, also evolved swiftly.  The Tuatara findings dispute this, perhaps indicating that there is no relationship between the rate of molecular change and the rate of physical change in a species. This small reptile, now confined to a few small islands of the coast of New Zealand (but also recently introduced to the New Zealand mainland once again), closely resembles the extinct reptile Homoeosaurus which dates from the Early Jurassic (180 million years ago).

David Lambert and his team have studied molecular change in a number of animals, extinct and extant populations, including Adelie penguins, foxes, lions, horses and the Cave Bear (Ursus spelaeus).  Of these animals, the Tuatara has a faster rate of DNA evolution.   The information will assist scientists as they try to conserve this endangered species and provide guidance as to future areas of study.  How helpful this rapid molecular evolution has been to the Tuatara genus has yet to be determined.  These animals are reputed to be extremely long lived with estimated life spans of between 100 and 300 years.

Living in Burrows

The reason why the Tuatara has survived at all is more down to luck than judgement.  These small lizard-like animals live in burrows and are relatively slow moving, their populations are soon overwhelmed if predatory mammals such as rats are introduced into their habitats.  The fact that New Zealand was isolated from other land masses before land mammals become abundant probably resulted in the survival of this species, the speedy DNA of the Tuatara had nothing to do with this species survival.

The Tuatara remains severely threatened, this representative of an ancient reptile order cannot compete against introduced animals such as rats and cats.  Indeed, even when these predators have been eliminated from the Tuataras few remaining strongholds, they may still face extinction.  As global temperatures rise this is affecting the balance of males and female Tuataras being hatched from eggs.  The warmer climate has meant that more eggs are hatching as males (temperature seems to be a determinant factor in deciding the sex of Tuatara offspring).  Fewer females in the population could lead to a critical decline in the breeding population.

To read more about attempts to re-introduce the Tuatara to the New Zealand mainland: Living Fossil helped back to New Zealand mainland.

1 04, 2008

Dinosaur Death Throes – Not what they Seem

By |2022-11-14T07:27:36+00:00April 1st, 2008|Dinosaur and Prehistoric Animal News Stories, Educational Activities, Main Page, Palaeontological articles|2 Comments

Dinosaur Death Throes – Not what they Seem

One of the questions we were asked recently was why do all meat-eating dinosaurs seem to fossilise in the same way?  A young dinosaur fan had pointed out that a picture in his dinosaur book showed two Coelophysis skeletons one of which had its neck and head curved backwards over the spine with the tail curling back on itself.  In the same book, there was a picture of a Compsognathus fossil with the head and neck also curved over the back.  How could these two dinosaurs have died in the same way?

Dinosaur Death Throes

We are familiar with these exhibits, the Coelophysis probably come from the famous Ghost Ranch deposits of New Mexico, where over 100 individual skeletons of this early Triassic theropod have been discovered.  The Compsognathus example probably relates to the nearly complete Solnhofen specimen from southern Germany.  This fossil was discovered in the lithographic limestone deposits in the same area as the first Archaeopteryx fossils.  Compsognathus was a resident of the Jurassic, Coelophysis the Triassic, how could these two animals separated by millions of years have died in virtually the same posture?  Indeed, when some of the Archaeopteryx fossils are studied, then they too show the head typically arched backwards over the spine.  The tail does not curve round to any real extent, perhaps the tails of these early birds were too ossified to permit such movement, or maybe it is to do with the conditions of fossilisation at the southern German sites.

This phenomenon is not restricted to just some dinosaurs, a large number of articulated theropod (meat-eaters) fossils show this trait.  Such postures are also seen in pterosaur fossils and birds.  As we have driven along on our travels in the USA and elsewhere we have observed birds that have hit car windscreens and been killed.  As the carcase dries out under the hot sun, the neck often adopts a curving posture.

An Exhibit of an Articulated Albertosaurus skeleton (Royal Tyrrell Museum)

Picture credit: Everything Dinosaur

The picture above shows a typical example of an articulated theropod fossil with the head and tail curving towards each other.

Most scientists believe that this common posture is caused by either one or a combination of two factors of post-mortem processes (after death).  The first of these processes involves muscle contractions causing the neck and tail to bend over.  Secondly, the posture could be caused by the the drying out of tendons and ligaments within the body as it remains exposed to the sun.  Whether it is due to rigor mortis or the desiccation of the body, both possibilities indicate that these bodies must have remained intact on the ground for sometime before finally being buried.

Examples from the Natural World

These are valid explanations, borne out from our own observations of roadkill in hot climates, however, having visited Africa on numerous occasions we also note how rare it is for dead animals to lay undisturbed without attracting the attention of scavengers.  One of our colleagues remembers working in the Masai Mara of Kenya when they had the misfortune to come across the body of a mature hippopotamus that had died only a few metres away from a small oasis which was being studied so that local elephant movements could be plotted.

Over the next few days, the pungent aroma of the rotting beast attracted a number of scavengers including hyenas, lions, marabou storks as well as vultures and the resident Nile crocodile.  It was not long before the remains of the hippo and been well and truly taken to pieces.  There were plenty of scavengers around in the Mesozoic, why were many of the bodies of the theropods not disturbed by other animals looking for an easy meal and the remains scattered about?

Another intriguing explanation for this death pose has recently been put forward.  There are certain conditions, most closely associated with warm-blooded animals such as mammals and birds that can lead to this posture.  A posture that is adopted when the animal is very much alive.  One such condition is opisthotonos, this can lead to animals adopting a very rigid posture with the head and tail curving towards each other.  This severe arching is caused by irritation of the membranes surrounding the brain or the spinal cord.  In humans this condition is associated with meningitis in infants.  Opisthotonos can also occur if there is brain damage (most notably the cerebellum), or any form of brain impairment leading to disruption to the nervous system.

There is some evidence of face biting amongst tyrannosaurs (another theropod), could many meat-eaters have suffered brain injuries when competing with other dinosaurs, this might have resulted in the condition that led to the “death pose” posture.

A Model of A T. rex Carcass

Dinosaur death throes

T. rex corpse.  An example of dinosaur death throes.

The picture (above) shows a model of a T. rex carcase, with the figure in the typical “death” position.  This model is part of the CollectA Age of Dinosaurs Popular range: CollectA Age of Dinosaurs Popular Range.

As this disorder is most commonly associated with higher animals (mammals and birds), which are warm-blooded could this theory if true, also lend weight to the hypothesis that dinosaurs, at least the active, hunting, theropods were endothermic?

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