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Tyrannosaur Paleobiology: New Research on Ancient Exemplar Organisms

Brusatte et al. (2010) Tyrannosaur Paleobiology: New Research on Ancient Exemplar Organisms. Science Vol. 329. no. 5998, pp. 1481 - 1485.doi:10.1126/science.1193304

Tyrannosaurs, the group of dinosaurian carnivores that includes Tyrannosaurus rex and its closest relatives, are icons of prehistory. They are also the most intensively studied extinct dinosaurs, and thanks to large sample sizes and an influx of new discoveries, have become ancient exemplar organisms used to study many themes in vertebrate paleontology. A phylogeny that includes recently described species shows that tyrannosaurs originated by the Middle Jurassic but remained mostly small and ecologically marginal until the very end of the Cretaceous. Anatomical, biomechanical, and histological studies of T. rex and other derived tyrannosaurs show that large tyrannosaurs could not run rapidly, were capable of crushing bite forces, had accelerated growth rates and keen senses, and underwent pronounced changes during ontogeny. The biology and evolutionary history of tyrannosaurs provide a foundation for comparison with other dinosaurs and living organisms.

More subsections under Feeding strategies

The section "Feeding strategies" has been greatly expanded, but it is one huge chunk of continuous text, and it would help the reader if it was broken up into subsections. I can't even keep track on it. FunkMonk (talk) 02:01, 6 September 2013 (UTC)

I think that would be a good idea. DinopediaR (talk) 05:30, 7 September 2013 (UTC)

Also, remember italics for binomials and genus names! Good work, in any case. FunkMonk (talk) 06:55, 7 September 2013 (UTC)

Thank you. I will do my best. DinopediaR (talk) 03:24, 8 September 2013 (UTC)

It is getting very long, perhaps it should be a spin off article? "Tyrannosaurus feeding behaviour" or some such? FunkMonk (talk) 13:56, 23 November 2013 (UTC)

Yeah, it is getting incredibly long and might be hampering page load time. I could always make a Feeding behaviour in Tyrannosaurus article and then put the info there, with a link to it under that section here, so as to speed up load times and make it more convinient. Would that be a good move for all of us? Dromaeosaurus is best dinosaur (talk) 18:49, 13 March 2014 (UTC)

Done, and it seems the page loads a lot quicker with the split. Dromaeosaurus is best dinosaur (talk) 19:32, 13 March 2014 (UTC)-

Yeah, this article should still summarise that info here, though. FunkMonk (talk) 22:17, 13 March 2014 (UTC)

I would have hesitated in splitting the article, since I think it is stronger as a whole than in separate parts. Readers could better relate and find connections between the different points/parts of the article. But I guess page load time and system performance is also important for usability. I think the summary for the feeding strategies could use a bit more work though, since it just seems to be a copy of an older version of the subsection and does not include some key points that were later added the longer version.DinopediaR (talk) 05:06, 17 March 2014 (UTC)

There are article size issues to consider though: https://en.wikipedia.org/wiki/Wikipedia:Article_size#Size_guideline Even after the split, it exceeds the 100 kb recommendation.FunkMonk (talk) 10:27, 17 March 2014 (UTC)

Any volunteers?

Looking at the page's edit history, there has been a lot of recent disagreement over what appears in the description for Matt's reconstruction. It's currently set to "Restoration of T. rex showing hypothetical feathery coating, as implied by phylogenetic bracketing." If this is what you want, I'm fine, that's all well and good.

The question is, if this is the way we are going, who is going to volunteer to go and add "showing hypothetical scaly coating" to every single reconstruction on the pages for carnosaurs, megalosauroids, coelophysoids, plateosaurids, pachycephalosaurids and every other clade that we don't have direct impressions from?

At least Tyrannosaurs is in a solid bracket. — Preceding unsigned comment added by Tomopteryx (talk • contribs) 12:32, 16 November 2013 (UTC)

Yeah, this is getting kind of ridiculous, really. A feather coat for T.rex is about as likely as a furry coat for Panthera leo atrox these days; I still don't see why it's "hypothetical" to add feathers but not so to add scales. Maybe a preservation bias? ;P Dromaeosaurus is best dinosaur (talk) 13:29, 20 November 2013 (UTC)

It's about as likely as a furry coat for an elephant or a rhino. Yes, bracketing implies that Rex had feathers, but plumaceous, not pennaceous as you have them, so the image is quite definitely OR, and based on current evidence is most likely wrong. And the fact that the lineage had feathers does not mean that every member was covered with them, especially the larger ones. They could have hatched as downy chicks, but lost them as they grew, or perhaps retained them in certain spots for display. But what you have looks like it's prowling the Arctic tundra. — kwami (talk) 20:49, 20 November 2013 (UTC)

"But what you have looks like it's prowling the Arctic tundra." It's actually based on the feathering of emu and cassowary, which prowl humid tropical forests and the Australian outback, respectively. But out are aware that Tyrannosaurus rex remains are also reported from the Cretaceous arctic, right? If I prowled the Outback in a cloak of emu feathers (a bird which weighs almost as much as I do), I would quickly die. Being a mammal, with a completely different system of respiration, ventilation, and integument, as are elephants and rhinos.

What is the precedent for any feathered animals losing feathers as they grow? This strikes me as baseless speculation. At what point in tyrannosaur growth do you suppose the feathers were lost? Why are they ok in chicks but not say, horse-sized or bison-sized individuals? (Because chicks are supposed to be "cute", maybe, and it is not ok for a predatory dinosaur to resemble something cute and funny instead of a sci-fi monster?) The feathers as depicted are intended to be plumulaceous, like those of basal tyrannosauroids, ratites, compsognathids, and ornithischains, not pennaceous. The depiction I uploaded is representative of one plausible extreme. If somebody would like to produce a scientifically plausible restoration closer to the other extreme, I'm all for it. But right now as far as I can see, mine is the only one within the plausible range.MMartyniuk (talk) 21:03, 20 November 2013 (UTC)

The speculation I've seen is that the larger dinosaurs in warmer climates probably did not have insulating coats. There are also no extant birds anywhere near the mass of Rex. (Even Yutyrannus was only 20% the mass of T. rex, and AFAICT it lived in a colder climate.) Speculation by those in the field carries weight, since all reconstructions are speculative. They could very easily be wrong, and perhaps none have thought to consider the difference between mammals and birds, but we don't get to speculate on our own, not in the article.

No precedent, just speculation by paleontologists that just because an animal is too large to sport feathers as an adult doesn't mean they didn't have them when young. Anyway, that's irrelevant here as we're not depicting young.

Deinonychus may well have been fluffy. It's not a matter of cute, it's a matter of the ratio of surface area to volume and the resulting efficiency of heat loss or retention.

Ratites have pennaceous feathers (the defining feature being a central vane, not barbules), and what you have on Rex looks a lot like ostrich feathers. Those are not supported by evidence from tyrannosaurids or anything more basal than tyrannosaurids. They're also 5× as long as the 20 cm of the longest known feathers on Yutyrannus. — kwami (talk) 21:35, 20 November 2013 (UTC)

Minor point, but should be corrected. Pennaceous feathers are known as basally as Sinosauropteryx (see citations in the Wiki article) and soon to be published ornithischian. They appear to be basal to Dinosauria at most and Coelurosauria at least. Reports that these are plumulaceous seem to be based on taphonomic distortion. Usage of pennaceous/plumulaceous is applied inconsistently in literature, down feathers are often described as plumulaceous despite having a weak central rachis. Sinosauropteryx feathers are reportedly similar to modern down on close inspection. MMartyniuk (talk) 13:29, 21 November 2013 (UTC)

The largest birds we know of (recently extinct elephant birds, moas, Haast's Eagle, etc.) definitely had dense feather coats. Not the size of Tyrannosaurus, obviously, but we have no evidence of any kind of large, naked bird. As for new restorations, I think the current one works, but discussion of feather type and extent is probably alright in any case. FunkMonk (talk) 22:26, 20 November 2013 (UTC)

We have nothing to compare a tyrannosaur to, so anything we postulate is simply speculation. Many paleontologist have assumed that, like large mammals, they would have had sparse or localized feathering if they had any at all. They may well be wrong, of course; Yutyrannus was a surprise. But what little data we have suggests that T. rex was not feathered to the extent of Yutyrannus. That's the best info we have at present, and it flatly contradicts this image. Thus the image is unabashed OR, and as such has no place in an encyclopedia. — kwami (talk) 10:14, 21 November 2013 (UTC)

Most of the life restorations we post contain speculation and are to varying degrees OR, they have to. That said, there are publications that mention that tyrannosaurs might have had a mix of feathers and scales. The best we can do is follow whatever evidence is available, skeletal proportions, skin impressions and phylogenetic bracketing. With Tyrannosaurus all we know is that some parts of it's body had small patches of ~2mm scales and it is nested within a group covered in feathers. At this point in time you can illustrate Tyrannosaurus mainly covered with feathers, mainly covered with scales, or anywhere in between and they can all be supported. No one mentioned anything when we posted pictures of feathered ornithomimosaurs which at the time didn't have clear skin impressions nor did anyone mention anything with depictions of feathered Therizinosaurus, why just Tyrannosaurus? An easy fix is to have a second restoration showing mainly scales and possibly naked skin with a caption along the lines of, 'a restoration of Tyrannosaurus showing scales as implied by skin impressions'. That would show to the casual viewer both extremes and that it's not certain what type of covering Tyrannosaurus had. Steveoc 86 (talk) 13:09, 21 November 2013 (UTC)

That would be a good idea. About this specific image, though, it shows T. rex as being five times as fluffy as Yutyrannus, when the fossil evidence is that it was less. And do we have no artistic renditions done under the supervision of someone who works on these animals that we could use for guidance? — kwami (talk) 13:33, 21 November 2013 (UTC)

Another thing to note is that Late Maastrichian North America was likely quite like China; the receding sealines show that it was actually getting colder near the end of the Cretaceous (and thus the poles were likely forming), meaning China likely wasn't the only tundra-dominated area in the world. And I'm pretty sure ratite feathers aren't truly pennaceous, but some sort of basal form of pennaceous (they do lack the shaft of a cardinal-like feather, IIRC) which, considering ratites are among the more basal birds. (Anseriformes are the first branch of crown Aves to appear, considering Vegavis is from 65.5 mya, right about the end of the Cretaceous, though galliformes, penguins, charadriiformes, anseranatids, anhimids and dromornithids all also arose at that time, so crown Aves sort of exploded in diversity at the end of the Cretaceous) In any case, most of the T.rex range likely was tundra, so a extensive feather coat (aside from underbelly and possibly the legs) isn't far-fetched. Dromaeosaurus is best dinosaur (talk) 14:49, 21 November 2013 (UTC)

Where does the idea come from that Cretaceous China was a "tundra"? The fossil plant evidence is unequivocal that the Yixian Formation was temperate and dominated by dense ginkgo and conifer forests, and seasonally cool and arid (meaning it had an autumn cold and dry enough for some degree of snowfall). Theclimate would have been similar to the US mid-Atlantic. I've never heard Washington, D.C. described as a tundra... MMartyniuk (talk) 15:59, 21 November 2013 (UTC)

I didn't mean that Yutyrannus lived in tundra, but rather that our rendition of T.rex makes it look like a wooly mammoth. — kwami (talk) 01:26, 22 November 2013 (UTC)

Elephants have peculiar precedents. There is in Rhinocerotidae a tendency to develop semi-aquatic forms such as Rhinoceros, Metamynodon or Teleoceras. Being ostensibly hairless isn't the end of the story: these animals still have to thermoregulate behaviorally, wallowing/bathing in water/mud/dust and being active in the most amenable parts of the day and seeking cover at other times. I'm not sure large mammals outside of those lineages would necessarily resort to these or other adaptations let alone dinosaurs. Birds have generally pretty thin skin under the feathers and at least Santanaraptor's preserved skin hints at a similar state of affairs for coelurosaurs.[1,2]

You must surely have sharper sight that any of us to be able to discern the texture of the feathers in MMartyniuk's rough digital paint over.

"the fact that the lineage had feathers does not mean that every member was covered with them, especially the larger ones."

I don't think you quite understand how scientific inference in general and phylogenetic bracketing in particular work. While what you said is a good caveat to have in mind, what the evidence we have says is that an extensive covering is more likely than limited tufts (which says nothing about their length). Then there is also the phylogenetic signal: we have several small mammals that manage being mostly naked (armadillos, warthogs) and no bird. Theropods at least were more like birds than mammals. Beyond that speculating without further testing is indeed baseless.

As for authoritative speculation here is...

• Xing Xu:[3]

"Based on the presence of feathers in some extinct coelurosaurs and all living birds, this approach suggests that all coelurosaurs, with the possible exception of gigantic species such as Tyrannosaurus rex, are feathered."

• Thomas Holtz, Jr:[4]

"The evidence has been mounting that the big tyrant dinosaurs were descendants of fuzzy dinosaurs, and quite possibly fuzzy themselves"

• Paul Sereno:[4]

"In my lab, I have a T. rex fossil that shows the beast did not have scales,”(...). “But it’s only in China that we have the opportunity to see evidence of what replaced scales – feathers! The report is a red flag to Hollywood and some scientists who get wobbly legs thinking something as ferocious as T. rex might have been packaged with a soft downy overcoat. You’ll now be able to date any Hollywood film that does not give these brutes their feathery due!"

• Lindsay Zanno:[4]

"[Yutyrannus] doesn’t put the nail in the coffin on the debate over the body covering of T.rex, but it definitely weakens the argument that the tyrant-king couldn’t have had feathers,"

I get this impression you didn't read the papers I posted at the top of the talk page. Here is the pertinent bit:

"Saurischians and especially theropods have an extensive air sac system that would help thermoregulate.^[1,2,3] Birds today raise their feathers and and even shake their body at the same time to replace the air trapped by them.^[4] Feathers and fur aren't only heat traps as a steep temperature gradient works both ways.^{[5, 6]}"

The point with the mention of the air sac system is that it obviates the square/cube rule by providing extensive internal evaporative surfaces which the 3rd ref shows are more efficient at dissipating heat than the skin itself when the ambient temperature is the same as the internal one.

Also I think you're assuming by a peculiar default that the average temp estimated for that time would be a constant measurement. I live in a subtropical climate (Southern Portugal): winter is definitely cold, especially the nights.

Dracontes (talk) 19:34, 21 November 2013 (UTC)

The point about air sacs is an important one. However, your ref notes that the idea that large dinosaurs might have lost their feathers is a common one among paleontologists. It also does not give much support for our rendition. Xu says Yu's feathers may have been a winter coat, not shared with more familiar tyrannosaurs. Witmer calls Yu a "woolly tyrannosaur" and says there has been some "rather sketchy" evidence that Rex was not feathered. Sereno says that Rex might have been covered with a "soft downy overcoat". But that's not what we show. The article says in both the lead and body that the feathers were simple filaments. Our pic looks like they're intended to be vaned, pennaceous feathers like an ostrich has.

The small hairless mammals you note are burrowers. Birds may take advantage of existing burrows, but they don't burrow themselves. That's a likely explanation for the difference.

You don't need sharp eyes. Just measure the length of the feathers in silhouette, and compare to the length of the animal. The result is one tenth; for a 9m adult, that's 5× the 20cm max of Yutyrannus. If our image had showed T.rex with 20cm feathers, I would never have objected to it. — kwami (talk) 01:19, 22 November 2013 (UTC)

Actually, Maloney and Dawson state that longer feathers, especially those that those that fade to a white colouration proximally, are actually better at keeping an animal cool than shorter feathers, so arguments on them being too long are pretty unfounded. Ref: Shane K. Maloney, Terence J. Dawson (1995) "The heat load from solar radiation on a large, diurnally active bird, the emu (Dromaius novaehollandiae)" Journal of Thermal Biology Volume 20, Issue 5, October 1995, Pages 381–387.

Irrelevant now anyway as MMartyniuk has put up an excellent new reconstruction. User:Tomopteryx

"Might" is the operative word.

If you look closely at what I wrote you'll see I said "texture". What I saw on the earlier version was brushwork with little detail. If those were pennaceous or plumulaceous feathers was rather left to one's imagination. But now as Tomopteryx said it's moot. Though perhaps the lead needs to be updated according to Foth 2012¹ since he makes a cogent argument preserved feathers found so far in non-avian coelurosaurs are rather difficult to characterize regarding their structural details: crushed feathers look filamentous even if they are indeed pennaceous.

"Birds may take advantage of existing burrows, but they don't burrow themselves."

Birds do burrow to construct nests (see puffins, bee-eaters, etc). Conversely not all mammalian tropical burrowers are without pelage (marsupial mole, golden mole just to exemplify the obligate ones).

From what literature I've read recently, it's not nearly as simple a story as people would make it just based on physical principles. Here are a few enlightening papers on the thermoregulatory importance of integument: [2] [3]. Dracontes (talk) 00:45, 25 November 2013 (UTC)

• By the way, there are tonnes of restorations of fully feathered Deinocheirus and Therizinosaurus, which are as large as T rex, but no one seems to bring forth the "too large for feathers" argument there, probably because they are so bird like already. By the way, couldn't some kind of compromise be agreed upon for this image? I guess if the longest feathers were shaved a bit here and there that there would be less scepticism? FunkMonk (talk) 17:05, 21 November 2013 (UTC)

I've said several times I would be fine with an image closer to the other reasonable extreme. I just don't have time to work on it at the moment. The current image is CC-By--have at it! MMartyniuk (talk) 18:24, 21 November 2013 (UTC)

I guess it's up to the dissenters to give a clear idea of what their vision is then! FunkMonk (talk) 18:30, 21 November 2013 (UTC)

That's too much, the point is just to show feathers, the extend isn't really that important. FunkMonk (talk) 16:24, 26 November 2013 (UTC)

• On a related note, just found this photo on Flickr of a full size feathered Tyrannosaurus model! FunkMonk (talk) 15:39, 27 February 2014 (UTC)

Hah, pretty neat that this was put up on my birthday and I didn't even realize it. But still, it looks great. Maybe we could put it into the article somewhere? Dromaeosaurus is best dinosaur (talk) 23:04, 12 March 2014 (UTC)

Heheh, I put it under the skin and feather section that same day... FunkMonk (talk) 10:33, 13 March 2014 (UTC)

Semi-protected edit request on 31 December 2013

On the page about Tyrannosaurus, I would like to change an incorrect fact. Sue, the largest specimen of Tyrannosaurs, was actually 42 feet long and not 40. I would like it if you would please change that. NCharizard25 (talk) 23:35, 31 December 2013 (UTC)

Not done: please provide reliable sources that support the change you want to be made. The 40-foot length is backed up with a source. NCharizard25, you'll need an equivalent or better source that says it was 42 feet long to change it. —C.Fred (talk) 23:40, 31 December 2013 (UTC)

The wikipedia article Sue (dinosaur) does state that it was 42 feet long. Either the length in that page needs to be changed or the length in this page needs to be changed. The article Sue (dinosaur) doesn't seem to have sources as reliable as those cited here though. BigCat82 (talk) 23:08, 15 February 2014 (UTC)

More than 30 specimens?

This article mentions only 30+ specimens, while according to the theropod database there are just over 50+, this needs to be edited.--Dinoexpert (talk) 23:01, 18 January 2014 (UTC)

There's a lot more specimens that, "The Tyrant King" book lists all known specimens up to 2005, excluding "specimens consisting of only a braincase and/or a few skull bones, or only foot bones, or only caudal bones, as well as the countless specimens of T. rex teeth and isolated bones." and they list 45, then a recent paper by Jack Horner adds another 46 skeletons found during his 1999-2009 excavation project, some of them are also included in Larson's list but only about 3. The problem, I don't think there's a good source that lists an updated number of all known specimens, The theropod database is acceptable I think but it doesn't give a number explicitly right? it might looked as synthesis. Mike.BRZ (talk) 21:29, 24 January 2014 (UTC)

We actually need a better source, but if you count them there are at least 50 skeletons listed in the theropod database, why cannot we use that information to edit? even if it is not explicitly stated?, is it that much of a problem for Wikipedia?, or perhaps found the paper where the 100 specimens are cited.--Dinoexpert (talk) 04:49, 27 January 2014 (UTC)

We can use that calculation to edit. Quoted from Wikipedia policy WP:NOR: Routine calculations do not count as original research, provided there is consensus among editors that the result of the calculation is obvious, correct, and a meaningful reflection of the sources. Basic arithmetic, such as adding numbers, converting units, or calculating a person's age are some examples of routine calculations. See also Category:Conversion templates. BigCat82 (talk) 23:22, 15 February 2014 (UTC)

Semi-protected edit request on 19 March 2014

There was a T. rex that was 14.5-15 meters long (UCMP 137538) NCharizard25 (talk) 23:51, 19 March 2014 (UTC)

Not done: it's not clear what changes you want made. Please mention the specific changes in a "change X to Y" format. — {{U|Technical 13}} ^{(t • e • c)} 01:47, 20 March 2014 (UTC)

interpenetrated or interpreted?

In Paleoecology section, I found these sentences a bit odd: "This has been interpenetrated as a bayou environment..." "The region is interpenetrated to be semi-arid inland plains..." Both sentences are talking about paleoenvironmental "interpretation" of the fossil sites. The word "interpenetrated" in this context doesn't make any sense to me. Maybe typos? Any comments? --JikhanJung (talk) 19:22, 25 March 2014 (UTC)

Up to 6.8 metric tons

What makes the 6.8 tonnes estimate for Tyrannosaurus rex more plausible or relevant than the more recent 8-9 tonnes estimates? as far as I know, they are not based on some Bone circumference or bone strength or some ecuations made, instead they are based on some of the most modern scanning technics known, and are based on the actual skeletons and their volumes rather than separate bones or comparisons with elephants.--Dinoexpert (talk) 23:54, 12 June 2014 (UTC)