The Mini Dinosaurs from the Harz Mountains

FiReaNGeL writes "When unusually small dinosaur fossils were found in a quarry on the northern edge of the Harz Mountains in 1998, it was initially assumed that these were the remains of a group of young dinosaurs. This was a fallacy, as the Bonn palaeontologist, Dr. Martin Sander, recently discovered. At a maximum estimated weight of one tonne, they were only a fiftieth the weight of their closest relatives, the brachiosaurs, and thus by far the smallest of the giant dinosaurs which have ever been found."

Comments

Small Giants

[crazyjeremy]

Heh heh... he said "smallest of the giant dinosaurs"

Re:Small Giants

[Lectrik]

Heh heh... he said "smallest of the giant dinosaurs"

's a bit like being the most civilized monkey in the zoo...

Re:Small Giants

[NickFortune]

Shush you - or I'll set my minature giant space hamster on you.

Go for the eyes, Boo! GO FOR THE EYES!"

Re:Mini-people

[afaik_ianal]

This may fit in elegantly, but last I heard (maybe even on slashdot) this discovery was now believed to be a normal human with a disease of some sort.

It's still disputed. Wikipedia has a short summary of the 2 opinions here: http://en.wikipedia.org/wiki/Homo_floresiensis#A_n ew_species.3F

The thing I don't understand about the hypothesis that the fossil is actually a diseased human, is that they found partial fossils of 8 other individuals, which I assume were consistent with the near-complete fossil being debated. What are the chances of them all having this extremely rare defect, given that it shortens life expectancy, and severely limits normal brain function?

It's hotly contested.

[jd]

Near the site of the "hobbits", they have found fairly advanced stone tools and stone arrowheads. People so acutely affected by the suggested dwarfing disorder would have inhibited brain function and certainly could not have developed an advanced technology or operated it. This makes it somewhere between unlikely to impossible for all of the people on the island to have been mentally afflicted. This leaves only two options - either these remains are of extremely unusual people, and were in a community of more typical hominids, and it's pure chance that no remains of these typical hominids have been found, OR they genuinely were a miniaturized subcategory of hominid that were not impaired at all, so there is no contradiction involved with there being an advanced technology.

The debate has likely intensified even further with recent genetic studies of Neanderthals, using mtDNA extracted from the teeth. This is because the mtDNA shows vastly greater variation in early Neanderthal genetic makeup than had ever been expected. So much so that all prior studies are now considered grossly inadequate, as they only examined a hundred or so base pairs, considering the rest to be essentially identical. If genetic diversity in early hominids in general was as great as genetic diversity in early Neanderthals is believed to have been, then the probability of there having been a natural experiment in hobbits is considerably greater.

There is, however, one outstanding problem that has NOT been resolved. Dwarfism on islands is common with reptiles. Reptiles do NOT do islands well. However, mammals on islands tend towards giantism - Amblyrhiza Inundata (a giant rat the size of a grizzly) being an excellent example. Birds, although descended from reptiles, also seem to do well on islands - the Moa (a flightless bird that was 13 feet tall) and the Haast Eagle (the largest eagle that ever lived, with a wingspan of 14 feet), both from New Zealand, being good examples. This is because mammals scale well and therefore lose very little by being large, even when resources are scarce. Reptiles don't scale so well, so there is a loss of efficiency in being large. No big deal on a large enough land mass, but on an island, it's a major problem.

Humans, because they are potentially much better at cooperating, are capable of planning and storing, and are able to access a much wider range of foods over a much greater range of environments, should (based on knowledge of other island-based mammals) scale up on islands extremely well, and should only shrink where conflict is greatest, which would typically be a continent. It's hard to say if this is the case, as humans have always been amazingly mobile, but my gut feeling is that you'll find more very tall people on or around islands than you will in the middle of continents. This creates a problem for the hobbits, though. Mammals shrink when being able to run is a far greater survival trait than being able to gather more. On an island, there is very little to run from and almost nowhere to run to. There should, therefore, be no advantage to them being that small and therefore no reason for such a trait to be selected.

I think it likely that the hobbits are indeed a new branch of hominids, but without a good, solid explanation for why they would be small, the theory will never be acceptable to any evolutionary scientist worth a damn, no matter how much they want it to be true, simply because it runs counter to what we know about mammals on islands. Answering that one question will probably quell a lot of the more skeptical scientists, too. A mechanism that ties things together and presents a coherent picture is more acceptable than an extrapolation, no matter how many fossils it is from.

Re:It's hotly contested.

[sumdumass]

How do we explain pigme people in africa? And what is to say these hobbit people originated on the island. It could be very well be that they came ot the island after fleeing from somewere else. As evolution placed the genes in pigmes, it could be the same with the hobbit people. Once it is there, it stays until watered down by outside influences just like the pigme people in africa.

Could it be that we just don't have enough fossil or other records to even prove our current theories as fact. Sure everything points to it being this or that but what if we are missing a very large portion of the story.

Re:It's hotly contested.

[Anonymous Coward]

Also don't forget the dwarf woolly mammoths that inhabited Wrangel island until a few thousand years ago (well in to the current interglacial).

http://en.wikipedia.org/wiki/Dwarf_mammoths

Clearly there are multiple factors at work that affect dwarfism or gigantism. It's not possible to predict the effects of living on an island for any particular kind of animal without a lot more information. This other information might include, size of island, nutritional requirements, habitat, population dynamics, behavior, climate, other animals (predators and competitors for resources), topography, behavior, and probably much, much, more.

NOTE: IANAEB (I am not an evolutionary biologist).

Re:It's hotly contested.

[callistra.moonshadow]

There are many theories running rampant about the so-called Hobbits, from misidentification to the reduced brain hypothesis. Many pressures in an isolated environment can create enough genetic pressure to lead to odd physical changes. Examples are twin studies of Andes Mountains dwelling children. When separated, one twin staying in the higher elevations and the other growing up at sea level researchers have noted drastic differences in the physical morphology. These observations hold true even though the monozygotic twins are genetically identical. The Andes-dwelling child had a large barrel chest and was shorter. The child living at or near seal level was not barrel-chested and taller. Most creatures within the animal kingdom have within their very genetic code a certain level of plasticity that we've seen demonstrated again and again as in the example above. It is not that surprising that there might have been some recessive gene that was expressed in an isolated population. It may not have been due to brain-reduction, but simply local pressures. Until they can actually identify some kind of smoking gun that can state with pretty good clarity that they can prove that these individuals didn't make the toolkit discovered, I'm more open to the possibilities.

Re:It's hotly contested.

[stonecypher]

This is a common misunderstanding in the mechanisms underlying natural selection. It is not the case that there's just one direction that things inevitably go, or even in fact that there's a definitive pressure applied by a given type of environment. It is often the case that several contradictory pressures are applied at once, and in many cases a species branches to fulfill both of them.

In fact, it's worth noting that all five of Earth's five biggest reptiles are in the setting that you suggest that they do not do well - the Crocodile Monitor from Papua New Guinea, the Komodo Dragon/Monitor Lizard from the Komodo Islands, Varanus Gigentis which lives on the islands around the coasts of Australia and New Zealand, the Goanna from Kakadu (also an island orbiting Australia) and the Water Monitor from Sumatra (the Nile Monitor is bigger than the Water Monitor, but they swim the oceans - they've been seen in Florida, Norway and Madagascar - so nobody knows where they're from, and locational pressure isn't an issue for them.) For that matter, the Butaan is in the Phillipines, and the Butaan is the only enormous tree lizard (also the only enormous herbivorous lizard) we're even aware of. And then there's Godzilla and Ghidra from Japan, Dark L'tzash "Dick Cheney" Sztsalit from Atlantis, and so on.

It is critically important to remember that speciation and trait selection are fundamentally stochaistic processes - they're _random_ , and in small populations there isn't enough buffer to clear out the mistakes. Sometimes an adaptation occurs not because of pressure, but the adaptation is so fundamentally different that it causes the ecosystem to change around it (the introduction of free oxygen through photosynthesis is the most dramatic example, but you see this gappen a lot when predators' targets are moved up and down the food chain, too.) Hell, sometimes an adaptation in Species A is a force for change in Species B. The oft-reported bit about the color of Rooks in London when industry happened, and made white birds easier to see than black birds, is frequently not followed through: there was a species of falcon which moved entirely away from brightness sight and towards motion sight, and the behavior of the rooks changed to made fewer and sharper turns to compensate.

This notion of "efficiency" isn't really that big of an issue to the reptiles; if it was, they wouldn't gorge and squat the way they do, which is tremendously inefficient (great cats do it too, except in the desert.) It is suspected that the reason some lizards shrink is to hide more effectively in an island where there isn't much room to hide. That explains neatly why it doesn't happen to the lizards that manage to stay at the top of the food chain; they just have no reason to hide in the first place. This is nicely seen in the Blackthroat and Red Acanthurus monitors, both who are from the same part of Indonesia - the Blackthroat got a thicker skin and a stronger jaw, making it the bad boy on the block, but the Red got a hide that looks like the local underbrush, shrank and got a brief turbo boost like crocodiles have.

I think it likely that the hobbits are indeed a new branch of hominids, but without a good, solid explanation for why they would be small, the theory will never be acceptable to any evolutionary scientist worth a damn, no matter how much they want it to be true

Yeah, um, wrong. Genetic historians know that not everything happens for a reason; it's a question of survival. We didn't evolve for spina bifida or kleinfelter's syndrome; it just happened. Sometimes those random things are good - eyeballs. Sometimes they're bad - mongolism. Sometimes they're a mixed bag - sickle cell anemia, which though it causes potentially fatal episodic shock, confers significant resistance to malaria, which before medicine was a pretty big win. Give those people another 50,000 years in the wild, and they'll probably develop a modified sickle cell which still fights the malaria but which doesn't clog the capillar

Canarysaurus

[Bob Cat - NYMPHS]

Someone was going to say it. Get it? Hartz Mountain Inc. sells bird seed? Little dinosaurs? No? I'll go back to Digg now...

Dinosaur Racing

[monkaduck]

Let's get that cloning going and get some dinosaur racing going on! C'mon, what's cooler -- betting the ponies or betting the 'saurs?

Oxymoron (love this word!)

[Nuffsaid]

Instead of the oxymoron "smallest giant", they should have said "smallest member of a family of dinosaurs whose other members are known to be giants, like the Brachiosaurus".

ObUnits

[Scarblac]

From TFA: "Their cousins, by contrast, were up to 45 metres long and weighed in at 80 tonnes - as much as a small town of over 1,000 inhabitants."

I don't understand. How many Volkswagen Beetles is that?

'Conspiracy' theory

[Netochka]

Anyone ever notice how as you go further and further back in history animals get bigger and bigger compared to their present day counterparts? Like, you go back a little while and you have stuff like mastodons, saber tooth tigers, etc... Then you go back farther and you have stuff like dinosaurs... Trilobites are just like huge bugs... Doesn't anyone else find it weird, like maybe the bones are expanding as time passes or something? Anyways, I don't actually think this is true, I'm just randomly rambling, being stupid.

Re:'Conspiracy' theory

[MichaelSmith]

Anyone ever notice how as you go further and further back in history animals get bigger and bigger compared to their present day counterparts?

• Big stuff lasts longer in the ground and is easier to see when you go digging
• Human beings kill the biggest animals around for food, this being the most efficent way to get dinner. Over time big things become extinct.

Smallest sauropod, most likely

[J.R. Random]

The article was slashdotted so I couldn't read it and this post is the usual Slashdot speculation. The smallest dinosaurs known were about the size of chicken. So I presume they meant this beast is the smallest known sauropod http://en.wikipedia.org/wiki/Sauropod. Most sauropods were humungous, so a one ton adult would be very small.