Posts Tagged 'size'

Giant hadrosaurs – Shantungosaurus

Another short post I’m afraid, more coming, honetly! This time out we have the absolutely giant hadrosaur Shantungosaurus.Here we have a life reconstruction that stands outside the Geological Museum of China in Beijing with me acting as a scale. As you can see, it’s massive and yet as far as I can tell quite a bit smaller than the supposed 17 m in length that this genus could reach.

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Although known from only incomplete skeletons, there is enough of Shantungosaurus from the various specimens known to accuraely reconstruct its anatomy pretty accurately and as hadrosaurs are pretty conservative (head crests aside) one would expect to be able to scale them pretty accurately to judge the size of even a very incomplete specimen. Nevertheless, that figure of 17 m is probably a bit of an exaggeration though perhaps not much of one – the musuem also holds part of a sacrum and that is enormous in its own right. Perhaps understandably we are rather fixated on sauropods or theropods when it comes to giants, but it is well worth remembering the enormous sizes of some of the ornithischians. Even if we clipped off a fem meters in length this would porbably remain one of the longest and heaviest ornithischians – it’s not all spinosaurs and diplodocoids.

The biggest and best

imgp1226There is often what could be described as an unhealthy preoccupation with size in scientific circles and especially in the reporting of science. The biggest species of a clade, of land animals, of predators, of all time etc. will always get you media coverage and certainly helps get papers published (T.rex might still be the most famous, but an awful lot of people have heard of Giganotosaurus simply becuase it’s big). I’m hardly immune to this, and my work on giantism and size changes and of course pterosaurs (which include the largest fliers of all time) makes me still more involved. However, while people are always happy to bang on about the largest of various groups (be it length, weight, height, or whatever) it can be hard to get an idea of what this really means. Even when you have a figure for a scale bar or some other good ‘standard’ to measure lengths with (for example, not elephants) getting a sense of scale is tricky and you are left with awkward compromises if you want to try and compare a lot of different things. Continue reading ‘The biggest and best’

Biggest bones?

I’ll be keeping this one short as there is really not much to say, however the photo is a really nice example of how extreme some bits of soem organisms get. While obviously there are some huge bones out there in various organisms (typically revolving around whale and ceratopsian skulls and the odd sauropod humerus) there are also some less likely candidates for biggest (well, OK, longest) bone of the vertebrate world – step forward the cervical rib.

Mamenchisaurus cervical rib This particular one is on display at the IVPP in Beijing and is to my knowldge the best and most complete of its kind. It comes from a specimen of Mamenchisaurs and is a staggering, wait for it, 3.2 m long! Thats right, over three metres and close on 11 feet. For a rib. That fits in the neck.

Not surprisingly things like this are not the easiest to find and preserve badly, you can’t see it in the photo, but there is a huge amount of glue holding it together (though it is definitely one piece) as it was essentially shattered when found. Still, it is a real demonstration of pushing simple bones to extremes and raises some interesting questions about the most basic mechanics of these animals. Mamenchisaurs has one of the most extreme necks of sauropods as it is, and support is an obvious function for a rib of this kind (you can see how straight it is, and that it would be held alongside the neck, and presumeably would overlap with the ribs of other cervicals). Still, it begs the question, how on earth did the neck flex with that buried in it, and if the neck did bend, was the rib pliable enough to bend itself? It is a complex question associated with a single simple rod of bone – science can be damned frustrating at times, but half the fun is finding out.

Incidentally, the feet in the frame are those of Mamenchisaurs, not the same animal but a reconstruction of one that was probably similar in size, which gives you a feel for just how big that thing is.

The unconsidered fatness of dinosaurs

I am always interested in ways of measuring or estimating the mass of organisms. While estimates are generally given as a range rather than an exact figure (which makes sense of course) the range is generally there to provide for possible errors in the methodology – were the animals good runners so the legs should have a bit more musculature, was the tail a bit longer, were the neural spines a bit longer? But there is also a further component that is rarely considered (or at least not discussed) – how robust (or lets face it, fat) is the animal?

Now I am not going to criticise estimates for not considering fat tyrannosaurs (though John Hutchinson for example does work with ‘gracile’ and ‘robust’ morphs which accounts for the possible variation present), but those working from them (for e.g. mechanical analyses) should give them a little more thought in my opinion. While it is easy to look at a human population and spot, shall we say, some highly robust morphs, that is a result of excess food being available, not just changes in form or build. While at London Zoo, I worked with a pair of female giraffe where one was probably half a meter taller than the other, but a fraction of the girth – the latter (while a guesstimate) was probably 10% heavier despite a difference in height (measured) of around 7%, with the shorter animal being the heavier. At a more familiar level, while discussing mass estimates in Munich, my fellow pterosaur researcher Mark Witton revealed that he weighs just 65 kg, compared to my then (to my shame, and I desperately point out, after a major sports injury that had prevented any real exercise for months) almost 100 kg, despite the fact that we are near identical heights and similar in build (well, broad shouldered). Even at my more normal ‘fit’ weight of about 85 kg there is clearly a big difference between us despite our similar height (and build actually, at least in terms of shoulder width). Mark is simply far more gracile than me for want of a better term, despite an apparently similar osteology. Either of us would probably be considered well within the normal range of humans, (and perhaps for other animals – i.e. about 20% for a given size) but it is really quite dramatic.

Assuming (i.e. not checking) this is normal, even a near perfect estimate that gave T. rex a mass of say 8 tons, means that for a given skeleton, anything from 6.4 – 9 t might be in the normal, let alone extreme range for the species. That is a big range and can have a considerable effect on wider analyses (such as running speed, ecological biomass etc.). Again, it might be difficult if not impossible to include this realistically into mass estimates (you are looking to get a narrow range after all for practical work, not be left with a hugely unworkable range that encompasses every concievable extreme) but it is worth keeping in mind what kind of variation is possible. Yes our hypothetical 8 ton rex might be a perfect estimate for that specimen when it was alive, but it could have been much bigger or smaller. Perhaps a very gracile form was normal, and rexes of that size rarely got above 6.5 t in which case an analysis of their food requirements for example could be severely affected. If the results come out for some ecological analysis for example suggesting that at an average of 8 t, Tyrannosaurs was badly overpopulated compared to the amount of prey, remember that he might not be quite the giant you think…

This is a revised Mk.1. post, to see the original with comments etc., go here.

How many elephants?

I do so love The Onion – for those who have missed it, it’s a satirical newspaper in the US that also has a very good online section. I spotted this recently (see it here) and while it raises a good chuckle as a concept, it does also highlight a point about science communication (yes, *that* again, or even, yes, that *again*).

I appreciate then when reporting these kinds of things (how big some new dinosaur is, how deep a new cave goes or whatever) it is incredibly useful to give people a frame of reference. Just how tall is 13 m? What does 50 tons look like? These are tricky concepts for people who are not used to dealing with things like that, so relating them to a familiar concept or everyday physical object will really help to get the point across.

However, the problem comes from the non-standard units being used. OK, so in the UK at least buses are pretty much uniform, but we are forever getting weights in elephants and heights in stories and these are hardly standard measures! I am looking out of a 7th storey windown into one that is on the tenth floor of the building opposite. Oh. So a putative dinosaur that could stretch to the 10th floor could be horrifying visitors in the hotel opposite, or I would be staring at the middle of its neck while it savaged (or not) people about 8 or 10 metres above me. Hmmm. And elephants. Adult female Indian elephants weight about half that of big African bulls. So if this dinosaur weighted the same as 30 elepahnts – which? I could double or halve its weight at a stroke….

Now I know this might seem pedantic (how unlike me), but this does seem to undercut the point of the comparison. The idea is to give people a frame of reference, but instead all it does is add ambiguity. Thirty metres is thirty metres whether Joe Public gets it or not, 10 storeys is not an SI unit. Ok, so it is also unreasonable to ask the press to say “weighed as much a 7 adult bull African elephants” instead of “weighed as much a 7 elephants”, as they just won’t do it, but they could at least find a better comparison. The Times is expecially good at this, using buses, football pitches (which while non standard, vary only a little in length / width) or well known buildings and landmarks like Nelson’s column, so it is certainly possible.

It is handy to get people to appreciate some of the numbers that science throws up, not everyone is au fait with light years, millions of years, tons, kph and the rest, either as absolutes or just concepts. Finding a way of expressing that is useful, it makes science more accessible. But it tends to be at the expense of actually communcating the figures in the first place. What’s the point of trying to show the public what ’30 m’ means if you use a highly variable reference point like the height of a house that leaves people with a frame of reference that could be twice the intended number?

This is a revised Mk.1 post, to see the original with comments etc., go here.

Estimating Dinosaur Sizes

One repeating theme of my research is the evolution of gigantism. Not just why or how some animals got to huge sizes but also answering questions about how they functioned. But what concerns me here is estimating the size of an animal based on what is frequently a little more than a few fragmentary remains. It’s something I think is rarely taken into account.

Of couse we first have to establish what we mean by ‘size’. Lets take a fairly obvious example – Brachiosaurus. We can talk about how big he was in 3 main ways – length, height, and weight (mass).

Although Brachiosaurus was a tall animal, no-one really uses height nowadays as a serious measure of overall size. After all, many dinosaurs were long but relativly ‘short’ in comparison to Brachiosaurus, like a typical *Mamenchisaurus*. Allthough height is, of course, it is still usefull for comparing some animals – notably hominids, but also for determining what browsing competitors Brachiosaurus is likely to have. So already we are down to two, but now it all starts to get a bit serious.
Continue reading ‘Estimating Dinosaur Sizes’


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