Monday, November 13, 2006

Will (11) from Lowestoft has a question about dinosaurs.....

was there ever such a creature as "giganotosaurus" (not sure about spelling?)and if so was it bigger than a T-Rex?
And my dad wants to know if Dino's were around for so long why didn't they evolve to be a bit more intelligent? Its always puzzled him.

Well Will, there certainly was such a thing as Giganotosaurs (yes, your spelling is right!) and it was indeed 'bigger' than Tyrannosaurs. Several fossils of Giganotosaurs have been found from the rocks of Late Cretaceous in Argentina, and it is one of the biggest known carnivorous dinosaurs. It was relative of Allosaurs (although it lived much later) and may have reached more than 15 meters in length! This is quite a bit more than T.rex, although T.rex was much bulkier and as a result was probably a heavier animal. Above is a reconstruction of the skull of Giganotosaurswith that of a human!

Giganotosaurs lived at the same time and place as the largest known dinosaur, the enormous Argentinosaurs that may have been up to 50 metres long, and weighted 100 tons!!! As a result, it has been suggested that Giganotosaurs was actually a pack hunter and took on these huge dinosaurs in groups. Here is a picture of a reconstruction of the two dinosaurs.

As for dinosaur intelligence it is a difficualt question to answer. Certainly some dinosaurs would have been quite smart compared to living animals. We can get an idea oof both an dinosaurs brain size, and how it was made up by the bones that surround it. From this we can see how big the brain was and what parts were devoted to eyesight, smell etc. There is also a general correlation of intelligence with the size of the brain and the size of the animal. Large animals need large brains, so a small animal with a large brain was probably quite smart. Certainly some dinosaurs (notably the advanced predators like Troodon and Deinonychus were about as smart as some modern birds like ostriches. Our own Darren Naish discussed some of these issues recently, look here for more.

As for why more dinosaurs didn't get more intelligent sooner, well thats impossible to say. Probably they had no need to, they only had to outsmart each other, so if everyone was at the same level there would be no big evolutionary pressure to get smarter. Darren's post looks at some of the consequences of super-smart dinosaurs and how they might have evolved.

Friday, November 03, 2006

Taj has a comment about prions.....

You said that prions are infectious. But they have no DNA? How can they be infectious if they don't have genetic material?

Hallo Taj, that’s a very good question. Prior to detection of prions, all known pathogens (e.g. bacteria and viruses) contain nucleic acid to reproduce. Prions, in contrast, seem to be devoid of nucleic acid. Treatments, which would normally destroy nucleic acid, don’t inactivate them. In 1982, the infectious particle was discovered (purified) by Stanley Prusiner and termed “prion”, a combination of the terms “proteinaceous” and “infectious”. The prevalent theory proposes that prions are infectious misfolded proteins, which reproduce in the absence of nucleic acid by transmission of their abnormal folding to the normally folded proteins in the host.

Thursday, November 02, 2006

10 year old Ian (our question man) has another question....

I have another question. Do you know if there have been any new fossil discoveries of desmostylans and/or sea cows in the past few years? I was wondering if desmostylans are more closely related to sea cows, elephants or hyraxes.

The latest studies of desmostylians indicate that they are more closely related to elephants than they are to hyraxes or sea cows. Within the placental mammal group Paenungulata (it includes hyraxes, sea cows and elephants), the desmostylians and elephants form a subgroup termed the Behemota, with the features that indicate their relatedness mostly being details of the teeth and ear region.

Another group - the obscure and poorly known anthracobunids - also appear to be members of Behemota (interestingly, anthracobunids are like desmostylians in being aquatic or amphibious. Given that elephants are also within this group, you might like to think what this tells us about the ancestry of elephants).

New fossil desmostylians and sea cows are published fairly regularly. One of the biggest discoveries within this area has been the 2001 publication of the Jamaican fossil sea cow Pezosiren - it is significant in that it still had hindlegs and could walk on land.

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