Those Not so Flexible Sauropods

The Sauropoda, that group of large, lizard-hipped dinosaurs with their long necks, huge bodies and long tails* have fascinated palaeontologists ever since the first enormous fossil bones of these plant-eaters were discovered.  Most natural history museums, if they are big enough, will feature sauropods amongst their dinosaur exhibits.  Although much has been learned about these Late Triassic to Late Cretaceous creatures since the days of Marsh, Cope and Riggs, palaeontologists still puzzle over many aspects of their anatomy.  For example, just how flexible were those long necks?

Sauropod Dinosaur Neck

New Study into the Long Necks of Sauropoda

A new study has been published that looks at the flexibility of sauropod necks. Picture credit: Everything Dinosaur.

Collaborative Study

In a new, collaborative study between researchers from the University of Utah, the Natural History Museum (London) and Bristol University the neck bones, and soft tissues of the necks of female ostriches have been used to try to model the flexibility of sauropod necks.  Why does this matter?  Well, the flexibility of the neck has all sorts of implications for the Sauropoda.  For example, very flexible sauropod necks would imply that these animals could reach high to feed on the tops of trees, or dip their heads very low to feed at ground level.

This feeding range, often referred to as the “feeding envelope” can be examined and contrasted amongst different sauropod genera permitting scientists to understand more about the feeding habits of certain species that co-existed.

Ostriches Studied

Previous studies had focused on the articulation and degree of movement possible by examining the cervical vertebrae (neck bones) of sauropods.  In this study, the team examined the bones and soft tissue found in ostrich necks (Struthio camelus), ostriches were chosen as they too, have elongated necks and the soft tissue such as muscle groups in the neck region are broadly comparable with that of sauropods.

The researchers measured the flexibility of the flightless birds with all their muscle tissue intact, and then slowly removed the muscles to test how this changed the situation and altered the range of movement possible.  The team’s findings suggest the soft tissues and cartilage associated with the long-necks of sauropods would have restricted their neck movements.  This has implications for the way these dinosaurs are depicted in films, books and displayed in museums.

Matthew Cobley from the University of Utah, one of the authors of the scientific paper that has been published in PLoS One (Public Library of Science) commented:

“Previous studies looked at the skeleton on its own and the assumption was that flexibility is limited by the bones of the skeleton, but our study shows it’s actually the soft tissue around it.”

The Impact on Feeding Strategies

The flexibility of the necks of these herbivores will have an effect on the feeding strategies that these creatures can adopt. There is a wide degree of variation in the shape of the cervical vertebrae, their number and the length of the neck in sauropods.  Each type of sauropod would most likely, have adaptations for exploiting food resources within a given environment.

Dinosaurs with different necks and other adaptations could reach and feed on different types of vegetation. With variation in feeding habits, an ecosystem could support a more diverse range of mega-herbivores.

Variation in Sauropod Necks – Adaptations for Different Feeding Strategies Perhaps?

Long necks for different feeding envelopes.

Picture credit: Everything Dinosaur/Safari Ltd

Different Sauropod Feeding Strategies

In the illustration above, examples of different sauropod anatomies can be seen, from diplodocid (top), camarasaurid (middle) and brachiosaurid (bottom).  The necks of these animals are very different, suggesting that each type of long-necked dinosaur was adapted to feeding on certain types of vegetation.  The diplodocids may have been browsers, whilst the brachiosaurs may have been better suited to feeding from the tops of trees.

It has been calculated that some large species would have had to consume as much as 400 kilogrammes of vegetation a day to sustain their immense bodies.  A herd of these herbivores would very quickly strip an area of suitable plant matter.  The competition for food amongst different species would drive the evolution of more specialised feeding and this may help explain why there is a large variation of sauropod species found in places such as the Dashanpu Quarry fossil sites in Sichuan Province, China.

These Jurassic aged sediments have revealed the fossilised bones of at least four different types of long-necked dinosaur.  Each was very probably adapted for feeding in a certain way.  Sauropods such as Mamenchisaurus and Omeisaurus with their extremely long necks would have specialised in one feeding method, whilst their contemporary, Shunosaurus with its much shorter neck would have probably browsed on other types of vegetation.

* Not all members of the Sauropoda were huge.  This is a very diverse group of Dinosauria, some sauropods such as the titanosaur Magyarosaurus  from the Hateg Formation may have reached lengths no longer than four metres and perhaps this dwarf titanosaur might have weighed about the same as a modern dairy cow.

For models and replicas of sauropods and other herbivorous dinosaurs: CollectA Prehistoric Life Models and Figures.

Texan Couple Play “Matching Pairs” with Fossilised Megalodon Tooth 

An American couple on holiday in Florida have an unusual memento of their vacation as each partner discovered part of the fossilised remains of a prehistoric shark tooth.  Last month, Texans Wes and Kerry Kirpach were holidaying at the beach resort of Venice (Florida) and during a dive off the coast to look for fossilised teeth they found the matching halves of a tooth from a Megalodon shark (Carcharodon megalodon).

Megalodon Shark

Venice is on the Gulf of Mexico coast of the Sunshine State, situated around fifty miles south of Tampa, it is regarded by many fossil hunters as the “shark tooth capital of the world” because of the wealth of shark fossil material divers and beachcombers can find.

A Carcharodon megalodon Fossil Tooth

A large fossil tooth from a Carcharodon megalodon.

Picture credit: Everything Dinosaur

Diving for Fossils

The couple have dived looking for shark teeth on many occasions and Wes was delighted to find a 9 centimetre long broken shark’s tooth, a fossil from the ferocious, whale-hunting Megalodon, which some scientists claim may have reached lengths of over fifteen metres.  Kerry found a similar sized tooth just a hour later.  Once the two pieces were examined, the cracks and breaks in the fossils could be seen to match each other, the couple had both found pieces of the same tooth.

Such an occurrence is extremely rare as depositional and tidal action will often disperse fossil fragments over a wide area, however, given the large number of fossils that have aggregated in the sea off Venice, it seems that unlikely events such as this are possible.

A Close-up View of Megalodon Jaws

The Papo Otodus megalodon model in anterior view.

Picture credit: Everything Dinosaur

Many Teeth in the Jaws

A fully grown Megalodon shark may have had up to 290 triangular teeth in its jaws and it has been claimed that the largest of these predators with its enormous jaws could swallow a Great White shark (Carcharodon carcharias) whole. The teeth of sharks are embedded into their fleshy gums and are not attached directly to the jaws.  These teeth are replaced constantly during the life-time of the animal with some sharks losing more than 20,000 teeth.  Replacement teeth steadily move forward as older teeth at the front are lost.  Shark teeth fossils are relatively common in a number of marine fossil deposits.

The broken tooth found by the Kirpach’s may be as much as four million years old.  Fortunately, for divers and for others who venture into the sea today, the Megalodon shark is believed to have become extinct around 1.6 million years ago.

A spokesperson for Everything Dinosaur commented:

“Giant sharks such as Carcharodon megalodon continue to fascinate, only yesterday one of our team members, whilst helping out a museum exhibition, was asked about their extinction.  Finding a piece of such a large prehistoric shark tooth is  rare and to have your partner come up with the matching half just a few minutes later is truly remarkable.”

Note

Following a taxonomic reassessment most scientists classify this shark species as: Otodus megalodon.

PNSO have produced a range of prehistoric shark figures including a replica of Megalodon. To view the extensive PNSO Age of Dinosaurs range: PNSO Age of Dinosaurs Models and Figures.

New Study of Psittacosaur Skulls Shows Three Species are Actually Just One Species

In a new study of Psittacosaurus fossils from China carried out by University of Pennsylvania researchers, the number of known species of this dinosaur has been reduced from fifteen to thirteen.  It seems that what was once thought to be three different types of “parrot lizard” living in China actually may be just one species.  Differences in the morphology of the fossil material had led to the establishment of three separate species but these differences relate to compression and distortion that occurred as the fossil material was buried and preserved, they do not relate to anatomical differences that would be expected if these animals were indeed different species.

Psittacosaurus

Psittacosaurus is one of the most abundant and speciose genera of all the known Dinosauria.  There had been fifteen named species, with fossil finds in Russia, Mongolia and Thailand as well as in China.  The research team, writing in the scientific jounal PLoS One (Public Library of Science), state that what was once thought of being three separate species from the Psittacosauridae family excavated from strata in the Yixian Formation of north-eastern China – P. lujiatunensis, P. major, and Hongshanosaurus houi are actually the same dinosaur.  All the psittacosaur material represents P. lujiatunensis.

Known to science for ninety years or so, psittacosaurs were relatively small, slender, bipedal members of the ornithischian group of dinosaurs.  Fossils date from around 130 million years ago to approximately 100 million years ago.  Most probably herbivorous, these dinosaurs, most of which were less than two metres in length, are distantly related to the giant Late Cretaceous horned dinosaurs such as Triceratops, Styracosaurus and Chasmosaurus.

An Illustration of Psittacosaurus

Psittacosaurus proves that three into one does go.

Picture credit: Everything Dinosaur

Three-dimensional Geometric Morphometrics

Commenting on their findings Peter Dodson, (Professor of Anatomy at the University’s School of Veterinary Medicine) stated:

“Because of the vagaries of fossilisation, no two fossils are the same.   Animals are alive and they die, but what’s crucial in palaeontology is what happens to the animals after they die.”

The research team used a process called three-dimensional geometric morphometrics to compensate for the crushed and distorted fossil material, thus revealing the affinities between different fossil specimens.  This is the first time this laser-based examination technique has been used on dinosaur fossils and this study could have implications for other genera.

New Study Re-assigns Fossil Material

Assessing the shape of dinosaur skulls.

Picture credit: PLoS One

Many New Genera Named

Over the last thirty years or so a large number of horned dinosaur fossils have been found in North America.  As a result, many new genera and species have been erected.  Three-dimensional geometric morphometrics if applied to North American ceratopsian specimens may help to confirm speciation or indeed lead to a re-assignment of some fossil material.

A spokesperson from Everything Dinosaur commented:

“This technique permits scientists to assess the variation in skull morphology.  Given enough specimens to study and this work could have implications for other dinosaur genera, extinct animals which have left us fossils which were thought to represent a new species unknown to science may turn out to be examples of already known and described species.”

The Beasts of the Mesozoic range contains several different, articulated horned dinosaur figures including Psittacosaurus (whilst stocks last).

To view the Beasts of the Mesozoic range: Beasts of the Mesozoic Articulated Dinosaur Figures.

165-Million-Year-Old Fossil Provided Evidence of Mammalian Evolution

A newly discovered fossil reveals the evolutionary adaptations of a 165-million-year-old proto-mammal, providing evidence that traits such as hair and fur originated well before the rise of the first true mammals.  University of Chicago scientists described the biological features of this ancient mammalian relative, named Megaconus mammaliaformis, in a paper published in the latest edition of the academic journal “Nature”.

Megaconus mammaliaformis

Professor Zhe-Xi Luo one of the authors of the scientific paper stated:

“We finally have a glimpse of what may be the ancestral condition of all mammals, by looking at what is preserved in Megaconus.  It allows us to piece together poorly understood details of the critical transition of modern mammals from pre-mammalian ancestors.”

An Illustration and Skeletal Reconstruction of M. mammaliaformis

Jurassic squirrel-like primitive mammal.

Picture credit: April Isch

The specimen, dating from the Bathonian faunal stage of the Middle Jurassic was discovered in Inner Mongolia, China.  Megaconus is one of the best-preserved fossils of the mammaliaform groups, which are long-extinct relatives to modern mammals.

A terrestrial animal about the size of a large ground squirrel, Megaconus was most probably an omnivore, possessing clearly mammalian dental features and jaw hinge.  Its molars had elaborate rows of cusps for chewing on plants, and some of its anterior teeth possessed large cusps that allowed it to eat insects and worms, perhaps even other small vertebrates.  It had teeth with high crowns and fused roots similar to more modern, but unrelated, mammalian species such as rodents.  Its high-crowned teeth also appeared to be slow-growing like modern placental mammals.

The skeleton of Megaconus, especially its hind-leg bones and finger claws, likely gave it a gait similar to modern armadillos, a previously unknown type of locomotion in mammaliaforms.

Preserved in the fossil is a clear halo of guard hairs and underfur residue, making Megaconus only the second known pre-mammalian fossil with fur.  It was found with sparse hairs around its abdomen, leading the scientists to theorise that it had a naked abdomen.  On its heels, Megaconus possessed a long keratinous spur, which was possibly poisonous.  Similar to spurs found on modern egg-laying mammals, such as male platypuses, the spur is evidence that this fossil was most likely a male member of its species.

Mammalian Phylogeny – Our Family Tree

Tracing the mammalian family tree.

Picture credit: Luo Laboratory

Professor Luo went on to state:

“Megaconus confirms that many modern mammalian biological functions related to skin and integument had already evolved before the rise of modern mammals.”

However, Luo and his team identified clear non-mammalian characteristics as well.  Its primitive middle ear, still attached to the jaw, was reptile-like.  Its anklebones and vertebral column are also similar to the anatomy of previously known mammal-like reptiles.

When asked to comment on the possible connections between this Mid-Jurassic fur ball and our own ancestry, the professor said:

“We cannot say that Megaconus is our direct ancestor, but it certainly looks like a great-great-grand uncle 165 million years removed.  These features are evidence of what our mammalian ancestor looked like during the Triassic-Jurassic transition.  Megaconus shows that many adaptations found in modern mammals were already tried by our distant, extinct relatives.  In a sense, the three big branches of modern mammals are all accidental survivors among many other mammaliaform lineages that perished in extinction.”

The fossil, now in the collections in Palaeontological Museum of Liaoning in China, was discovered at the famous Daohugou Fossil Site.  It was studied by an international team of palaeontologists from Palaeontological Museum of Liaoning, University of Bonn in Germany and the University of Chicago.

The Slab and Counter Slab of the Fossil

Megaconus mammaliaformis is preserved as a slab (left) and a counter-slab (right) of shale deposited in a shallow lake.

Picture credit: University of Chicago/Professor Zhe-Xi Luo

This specimen, and another fossil mammaliaform found in the same area in 2006 will help scientists to piece together the early evolution and radiation of primitive mammals that scurried around back in a time when the dinosaurs dominated.

Everything Dinosaur is grateful to the University of Chicago in the compilation of this article.

To view models and replicas of prehistoric animals: Dinosaur and Prehistoric Animal Models.