Stones in dinosaurs’ stomachs unlike ostriches’


From the University of Bonn in Germany:

Dinosaurs — stones did not help with digestion

The giant dinosaurs had a problem. Many of them had narrow, pointed teeth, which were more suited to tearing off plants rather than chewing them.

But how did they then grind their food?

Until recently many researchers have assumed that they were helped by stones which they swallowed.

In their muscular stomach these then acted as a kind of ‘gastric mill’.

But this assumption does not seem to be correct, as scientists at the universities of Bonn and Tübingen have now proved.

Their research findings can be found in the current issue of the journal Proceedings of the Royal Society (doi:10.1098/rspb.2006.3763).

What do you do if you do not have good teeth, and food is hard to digest?

Some herbivorous birds which have a toothless beak, such as ostriches, solve the problem with what is known as a gastric mill.

Their muscular stomach is equipped with a layer of horn and contains stones which help to break up, crush and thereby also to digest food.

Giant dinosaurs from the Jurassic and Cretaceous period (200 million to 65 million years ago) such as Seismosaurus and Cedarosaurus must have had similar digestive problems.

The animals, some of which weighed more than 30 tonnes, were the largest herbivores which have ever existed.

Many of them had a very small head, in relation to the size of their body, and narrow, pointed teeth, which were more suited to tearing off plants rather than chewing them.

At the same time, they had to digest enormous amounts of food for their rapid growth and the metabolism of their gigantic bodies. Smoothly polished stones, which were found in several cases at excavations involving skeletons of sauropods, are also interpreted as gastric stones.

However, Dr. Oliver Wings from the Institute of Earth Sciences at the University of Tübingen, and Dr. Martin Sander from the University of Bonn have shown that this cannot at least be a gastric mill such as birds, today’s relatives of the dinosaurs, possess.

Among these the ostrich is the largest herbivore. For their investigations, the scientists therefore offered stones such as limestone, rose quartz and granite as food to ostriches on a German ostrich farm.

After the ostriches had been slaughtered, the scientists investigated the gastric stones.

It became clear that they wore out quickly in the muscular stomach and were not polished. On the contrary, the surface of the stones, which had been partly smooth, became rough in the stomachs during the experiments.

The mass of the stones then corresponded on average to one per cent of the body mass of the birds.

‘Whereas occasionally stones were found together with sauropod skeletons, we don’t think they are remains of a gastric mill such as occurs in birds,’ Dr. Sander comments.

In that kind of gastric mill the stones would have been very worn and would not have a smoothly polished surface.

Apart from that, gastric stones are not discovered regularly at sauropod sites.

When present, their mass is, in relation to the body size, much less than with birds.

‘In comparing these we extrapolate over four orders of magnitude, from an ostrich weighing 89 kilograms to a sauropod weighing 50,000 kilograms. This may seem a bit daring.

However, within birds the range of body weight and corresponding masses of gastric stones also spans four orders of magnitude, from the 17 gram robin to the ostrich,’ says Oliver Wings, who moved from Bonn University to Tübingen only recently.

Yet what else were the dinosaurs’ gastric stones used for?

The researchers presume that they were accidentally eaten with their food or could have been swallowed on purpose to improve the intake of minerals.

But if the stones did not help to crush vegetable food, the sauropods’ digestive system must have used other methods, since the decomposition of large amounts of material which is difficult to digest requires the assistance of bacteria in the digestive system.

The smaller the pieces are, the better they can break down the food. Possibly, the scientists conclude, the intestines of the sauropods were formed in such a way that the food was retained there for a very long time, in order to improve the digestive process.

There is another group of dinosaurs, however, whose remains of gastric stones can be linked up with a birdlike gastric mill, according to Oliver Wings’ research.

From these dinosaurs known as theropods today’s birds developed.

The gastric mill could therefore have developed in the ancestral line of birds.

9 thoughts on “Stones in dinosaurs’ stomachs unlike ostriches’

  1. Swimming dino enters the history books
    24/05/2007 14h57
    The footprint of a carnivorous dinosaur
    ©AFP/File – Paulo Novais

    PARIS (AFP) – Twelve footprints found in the bed of an ancient lake in northern Spain have thrown up the first compelling evidence that some land dinosaurs could swim, researchers reported Thursday.

    The 15-metre (48.75-feet) -long track in sandstone “strongly suggests a floating animal clawing the sediment” as it swam against a current, they say.

    The swimmer is believed to have been a therapod — the vast family of carnivorous dinos that included the mighty Tyrannosaurus rex — which lived in the Early Cretaceous, some 125 million years ago.

    The trackway in the former lakebed consists of six asymmetrical pairs of two or three S-shaped scratch marks. Each set measures some 50 centimetres (20 inches) in length and 15 cms (six inches) wide.

    The prints paint a beguiling picture of a large, buoyant dinosaur whose clawed feet raked the sediment as it swam in a depth of some 3.2 metres (10.4 feet) of water, according to the paper, which appears in the June issue of the US journal Geology.

    Ripple marks on the surface of the site indicate the dinosaur was swimming against a current, struggling to maintain a straight path.

    “The dinosaur swam with alternating movements of the two hind limbs, a pelvic paddle swimming motion,” said co-author Loic Costeur of the Laboratory for Planetology and Geodynamics at the University of Nantes, western France.

    “It is a swimming style of amplified walking, with movements similar to those used by modern bipeds, including aquatic birds.”

    The question as to whether dinosaurs could swim has been debated for years.

    Until now, no firm evidence had come to light, just mysterious “ghost traces” at various sites.

    Asked by AFP to speculate as to which dinosaur may have made the tracks, Costeur cautiously pointed to the allosaurus — a bipedal carnivorous dinosaur with a large skull balanced by a long, heavy tail. Some allosauruses could reach more than 10 metres (32 feet) in length.

    The discovery opens up new avenues in dinosaur research, said Costeur.

    Computer modelling will be able to reveal more about anatomy and biomechanics, “as well as our view of the ecological niches in which they lived.”

    The Virgen del Campo track is located at the Cameros Basin in La Rioja, at the site of a delta to a former lake. The basin is already known as a treasure trove of footprints of walking theropods.

    Lead author is Ruben Ezquerra of the Foundation for Palaeontological Patrimony in La Rioja.


  2. June 03, 2007 11:22 pm

    Old bones stand tall at airport

    By Daniel Silliman

    Every month or two, the dinosaur has to be dusted.

    Will Grewe-Mullins drives out to the airport, Hartsfield-Jackson Atlanta International Airport, and finds the 33-foot-long Yangchuanosaur skeleton standing between two trees in the atrium of the north terminal. Grewe-Mullins used to do this in the middle of the day, in the afternoons when he made time to get away from Fernbank Museum of Natural History in northeast Atlanta, where he is the registrar. But every time he climbed up his ladder to dust the dinosaur, a crowd of the airport’s more than 84 million annual travelers gathered around him to watch and ask questions.

    What does the dinosaur eat?

    How old is the dinosaur?

    Was the dinosaur mean?

    Why is the dinosaur here?

    It made it hard to work.

    Now Grewe-Mullins does his fossil cleaning in the early-morning hours, when the airport’s shops are mostly closed and the seats surrounding the Yangchuanosaur are mostly empty. Sometimes the only person in the atrium, when Grewe-Mullins gets there, is someone sleeping through a long layover.

    Sometimes, they’re sleeping in the seats directly under the big, upright skeleton, and Grewe-Mullins has to wake them up and ask them to move.

    The dinosaur, believed to be a meat eater, was first discovered in 1976 during the construction of a dam in Yangchuan County in China. It has a long tail — about half of its overall length — serrated teeth, sharp, clawed fingers, likely hunted in packs, lived in the Upper Jurassic Period and was probably the largest predator of its time and place. The particular dinosaur that stands, silently, looking like it’s walking somewhere quickly and waving its arms, was donated to Fernbank by the Raymond M. Cash Foundation. After an exhibit called “Planet of the Dinosaurs” closed in 1999, the bones were packed into a crate.

    The museum curators, though, wanted some place to bring the dinosaur, called “The Asian Giant,” into the view of the public, and began looking at the highly public airport.

    “This was just kind of a way to give it new life,” said Fernbank spokeswoman Brandi Berry. “There’s no reason to have something crated up in a box when you could have it out in the public… It’s a great way to add a little bit of local flair to the airport.”

    The dinosaur, staunchly called by its scientific name by the museum staff, was leased to the airport for five years. Since the lease’s initial expiration, the airport’s art department has renewed it twice.

    “I don’t know why that particular (dinosaur) was chosen,” Berry said.

    Mostly, the giant figure of the Yangchuanosaur is ignored, in the atrium. Travelers walk by, janitors sweep by, and millions sit down to wait for an arrival or a departure without looking up at the very large teeth rooted to the bone skull above their heads.

    On Tuesday night, the atrium was quiet. Dusk settled and one man sat there, underneath the dinosaur, head in his hand and bag at his feet, sipping something from a paper cup. The dinosaur stands frozen in silence between two green trees. In half an hour, the only person to look at the skeleton was one teenager with a backpack, walking toward the baggage claim. He looked up briefly and continued talking to a friend.

    Sometimes, though, the dinosaur, whose insured value is undisclosed as part of the lease agreement but is considered to be “priceless,” is given unwanted attention.

    The dinosaur had its tail broken.

    A parent lifted a child up to the Yangchuanosaurus’ raised tail and let the child hang there. The museum had to put some pieces back together, rework the armature holding the fossil together and raised the dinosaur’s pedestal to keep the 160-million-year-old bones out of the way of friendly children and inattentive adults.

    Besides the one incident, however, the museum doesn’t do any upkeep besides the monthly or bi-monthly dusting.

    On the net:


    Hartsfield-Jackson Atlanta International Airport:


  3. Tunisia: Ecosystem Protection – ‘Red Neck’ Ostrich is Reintroduced in South West

    Tunisia Online (Tunis)

    2 July 2008
    Posted to the web 7 July 2008


    About twenty ‘Red Neck’ Ostriches (Struthio camelus) have recently been reintroduced in Tunisia ‘s national parks of the south west in Arbata (Gafsa), Daghmous (Tozeur), and Jebil (Kebili).

    Brought from the region of Agadir in Morocco the ‘red neck ostrich’ also known as the ‘North African Ostrich’ is one of the four sub species of the ostrich in the world.

    The operation of reintroduction of this big running bird which was carried out on Tuesday by the general directorate of forests, of the Ministry of agriculture and water resources, is part of the national program of protection and preservation of endangered species.

    Preserving these birds against poachers is also part of the mission of the general directorate.

    This big bird can reach 2,7 meter in length and weigh up to 230 kilograms . It an omnivorous species, living in semi arid conditions and can live up to 40 years old.

    Recently, the national parks of Arabata, Daghmous and Jebil witnessed the reintroduction of several other rare species, such as the Oryx and Dorcas Gazelles.

    Through several texts of Tunisia ‘s legislation which regulate animal hunting and trade, the competent authorities were able to preserve several rare and endangered animal and vegetal species, given their role in the protection of the ecosystem and the diversification of both fauna and flora.


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