The Year of Ceratopsians continues with two new additions to the Chasmosaurinae: Utahceratops gettyi and Kosmoceratops richardsoni. I will give you two guesses as to where the former was discovered. Here's one hint: It's in the name. There was absolutely nothing about this animal that warranted a better, more imaginative moniker. Meanwhile, Kosmoceratops is heavily airbrushed, full of fashion advice, and knows the top ten ways to make your bull go wild in the bedroom. Another surprise is that Chasmosaurus irvinensis is renamed Vagaceratops irvinensis, as it turns out to be closer to Kosmoceratops than Chasmosaurus.
But seriously, this is fantastically exciting. The paper was published in PLoS One and is thus freely available for all. Check out the paper by clicking this lengthy link, but don't be surprised if you can't see the pictures or download the paper as a PDF. It would seem that PLoS One went on hiatus the second this paper was announced, thus going from "awesome free-access journal" to "cocktease."
But don't cry about it--go to The Internets, where people have been blogging about these new dinosaurs all morning. Do you want to know more? Click these links to do just that!
Archosaur Musings
The Open Source Paleontologist
Dinosaur Tracking
Dinochick Blogs
Don't get too excited: they're probably all just ontogenetic stages of each other.
Posts
24 comments:
@ everyone:
Ohayo/Oyasumi nassai...
While the discovery of two new ceratopid genera is a good news to hear today, I would want to have a thorough physical and molecular analyses of the two to determine if the they are indeed their own genera. This is not meant to offend Horner or any other scientists, though. I'm just saying that the identification and establishment of an animal taxon should be based on all lines of evidence.
"Don't get too excited: they're probably all just ontogenetic stages of each other."
Bahahahahaha!!! XD
It's funny, though. First time I heard the name Kosmoceratops, my mind immediately went "crazy neighbor on 'Seinfeld'" or "Tall, colorful annuals beloved by goldfinches" instead of "stupid fashion magazine I am apparently supposed to like because I'm female."
By molecular, do you mean histological? (though I suppose that would be covered under physical) There's no way you're getting a molecular phylogeny out of fossils that old.
Just so everyone knows, part of the funding came from the National Science Foundation. Because the NSF doesn't want you to think that your tax money goes to waste, they share a lot of stuff with the public. On this story alone, they have a long article about the find, talking to the people who found and prepped the dinosaurs. They also have a cool video of Scott Sampson talking about the two dinosaurs and Laramidia, and Supersized photos of the dinosaurs, their skulls, and all kinds of other photos. They have a searchable news index and searchable media gallery, and they have a lot on other dinosaur finds. Link is http://www.nsf.gov/news/news_summ.jsp?cntn_id=117745&org=NSF&from=news if you want to see it yourself.
@ Tor:
No. what i mean is biomolecules (i.e. peptide sequences, genomic sequence). As for the viability of molecular phylogeny, the method is still applicable to fossils that old. It has already been done before (in the case of Brachylophosaurus, and Tyrannosaurus rex for instance).
First time I heard the name Kosmoceratops, my mind immediately went "crazy neighbor on 'Seinfeld'"
Don't worry, it wasn't just you. ;D
lol Kramerceratops!
"Don't get too excited: they're probably all just ontogenetic stages of each other."
Hahaha that made my day Zach! Even though these genera look radically different from each other, I can already tell the Hornerites will bend over backwards to look for a way to lump them or deny their independence ;) I'm curious to see what they do when detailed molecular analysis is done and their flagship theory most likely runs out of gas (like their scavenger T. rex theory did). What will their next one be?
@ Nima:
I agree with you for that part. Following Horner's logic in assessing vertebrate taxon classification using histology is, at the very least, potentially misleading. I know this forensic journal article is not a perfect example but it does show that examinations of physical aspects(i.e. skeletal anatomy, geo-chronological distribution, and most importantly histology) is not always truly accurate ((here is the link for such an example: http://onlinelibrary.wiley.com/doi/10.1111/j.1556-4029.2006.00368.x/abstract; 2006-2007 article by Miller and Bell that demostrates that histological examination of bones can yield misleading phylogenetic classifications). Remember that the genetic composition of men and chimps are 98% or 99 % identical about to each other (if genetic regulation mechanisms [i.e. insertion, deletion, splicing] is considered, it is still about 96 % identical) and yet that 1% or 2% difference results in very radically different appearances between humans and chimps. Another irony is that Horner, who himself had advocated using bio-molecular methods on fossils, did not examine the peptide sequence or the possible nucleotide sequences of the two ceratopid taxa.
"Hornerites will bend over backwards to look for a way to lump them or deny their independence ;)"
Oh for fuck sake! Seriously, theres no reason why this would be considered. Kosmoceratops and Utahceratops do not clad together and Scanella and Horner are not proposing the synonymy of Trike and Toro solely on the basis that the two forms co occur.
Hikaru, the histological analysis is not misleading, potentially or otherwise. The histology had no bearing on the phylogeny, there was no phylogenetic analysis even done. There would be little point, as its already been well established that Trike, Toro, and Nedo form an exclusive clad. The Histology is simply demonstrating that one population form is entirely composed of juveniles and the other is entirely adults. There is no potential for that to be misleading its well established how the bone histology changes with ontogeny and, again, it was never used to construct a phylogeny.
Molecular analysis is not any where near practical, or even informative at this point. And lets be realistic, if genetic material is ever recovered we are not going to get anywhere near the resolution that allows us to say that there is 1% genetic difference between chimps and humans, not with material that old. As for polypeptide sequences, they will be far more conservative than genetic material. Id be surprised if you'd be able to differentiate Triceratops from Iguanadon, much less sister taxa.
All the, histology, phylogenetic topologies, and stratigraphic lines of reasoning really have nothing to do with the thesis of the paper. They are supporting lines of evidence and are showing that the hypothesis stands up to rigorous testing. Any one of those could potentially falsify the hypothesis. The crux of the paper is the demonstrated morphological change in the frill which is consistent going from Triceratops specimens to Torosaurus specimens.
Guys, if you think there is a problem with the paper, then critique the evidence it provides. All your arguments thus far boil down to personal incredulity, straw men and ad homeniem attacks against Jack Horner. Its not enough to just sit on the sidelines looking at pictures on the Internet and saying "well you should have included this, and this and this particular aspect wasn't discussed, etc".
Yeeeah, that little "ontogenetic stages" comment was a wink wink nudge nudge comment, not meant to be taken seriously.
Yeah Zach, it was a pretty funny joke too. My "Hornerite" comment was obviously a joke too, some people took it seriously of their own accord.
Sheesh this is why people think paleontologists have no sense of humor... obviously if it can be done with Trike and Toro (and *gasp* Nedo) and Pachy and Styimoloch, Dracorex, Stegoceras, Prenocephale, etc. then it could just be a matter of time for Kosmo and Utah! (nudge nudge wink wink)
On an unrelated point, has anyone EVER heard of a species of animal where the adults are actually SMALLER than the juveniles?
@ Christopher:
Let me first clarify what my "misleading" remark mean. If you haven't read the example I gave in my posts concerning earlier topics, let me reiterate it here: suppose baleen whales are now extinct. Then, a specimen of humpback whale (genus Megaptera) and a specimen of blue whale (genus Balaenoptera)are found as fossils in one area, with the former being a subadult and the latter being fully adult and the cross-section of their bones are subjected to histological analysis (following Horner and Scanella's methodology). Without knowledge of the external appearance differences, internal anatomical differences, and molecular differences between the two (and sometimes, the difference between closely-related but distinct genera are only "skin-deep", just like in the case of genus Delphinus and Tursiops), one could misclassify the humpback whale specimen as the juvenile stage of the blue whale's ontogeny based on the appearance of the two animals' bone tissue structures(given that the skeletal anatomy between Megaptera and Balaenoptera are very similar only the proportion of the bones vary). I hope this example would be taken constructively, not as an attack to the person.
In connection to the above paragraph, I would also comment on your remark about how one population is composed entirely of juviniles and the other, of adults. I agree that it was well-established that Trike-Eotrike-Nedo-Toro form an exclusive clade. However, one should also consider the possibility that Triceratops and may have undergone neoteny or progenesis; hence the retention of "juvenile" tissue structure seen in that taxon.
About peptide sequence, I also agree that they conservative. It is possible that there may be no peptide sequence difference between Triceratops and Iguanodon. However, one should also consider that the same peptide sequences can be synthesized by an incredibly wide array of nucleotide sequences (ex. v-s-s-q-r-l-g-l-l-t; this could be synthesized by the following codes to name a few: 1)gua-uca-ucu-cag-cgu-cuc-ggg-uug-uua-aca; 2)guc-ucc-ucg-caa-aga-cua-ggc-cuu-cuc-acg; 3) gug-ucg-ucg-cag-cgc-cug-gga-cug-cug-acc). In addition to the possible nucleotide sequences I have given for the sample peptide chain, one should also take into consideration gene expression control mechanisms. Just as the same peptide chain can be coded by many different nucleotide sequences, a single nucleotide sequence could also code for a wide array of peptide chains.
Right now, DNA analysis is pretty much impractical. However, a preliminary genetic comparison between Triceratops, Nedoceratops, and Torosaurus may be possible in the next ten or fifteen years with the discovery of more specimens that have preserved a large amounts of soft tissues in good condition, and with the dinosaurian DNA bank becoming clearer with further discoveries. Alternatively, nucleotide sequences recovered from dinosaur fossils may be subjected to PCR in order to produce enough copies of nucleotide sequences for analysis. Until that time, we should not close the possibility that they may be their own distinct genera in their own right. Just because there have been no Torosauri specimens found to date that clearly display the fenestration in the frill at the same ontogenic stage as Triceratops juveniles and just because the tissue structures in Triceratops horncore and crest bones are "immature" compared to that of the former, that does not automatically mean that Torosaurus is the "granny" stage of Triceratops. As Carl Sagan have said before his death "absence of evidence is not evidence of absence". Furthermore, (I have mentioned this in my earlier posts) the said taxa could have had exhibited behavioral differences and ecological differences (such as food souces), which could have also separated them into distinct genera. For the meantime, more physical, ecological, behavioral, and molecular data are needed to further resolve this issue.
@ Everyone:
Finally-let me make it clear that I never intended to insult Horner in the first place. In fact, I cited him in my earlier post here PRECISELY because he is advocating the use of bio-molecular methods for dinosaur classification. What I'm trying to critique is the interpretation of the evidence presented in that paper.
To follow up on Hikaru's comment, I also never meant to insult Horner. First off, "insult" is a dirty word that should not be in any paleontologist's toolbox of arguments, and serious personal attacks are unethical and unscientific to say the least. Everyone knows about Marsh and Cope, we don't need a repeat of the Bone Wars.
Second, my main issue is not even with Horner, but with some of his self-proclaimed followers. People who claim "such and such has to be true because Horner said so" are just as dumb as people who claim "I will never buy a windows PC because Steve Jobs is my hero".
Of course Horner has his own share of valid arguments (in fact his book "The Complete T. rex", though I didn't agree with its conclusions, was a very eye-opening read with many valid questions that made me think a lot about varoius theories). However he has a lot of invalid and inconclusive ones too.
In fact the big irony here is that it was Horner himself who pointed out (back in 1993) that in paleontology things should never be assumed to be the way they seem, assumptions are often misleading, you have to search for alternate "devil's advocate" explanations before publishing stuff as fact. He made this point on everything form taphonomy to fossil assemblages to habitats to animal behavior to how you define what's an adult and what's a juvenile dinosaur.
And here we are getting big egos over what Torosaurus really was.
Regardless of what you may assume abut ontogeny, there's only a few ways to actually prove Horner's "toroceratops" valid beyond a reasonable doubt.
1. Find a herd of Triceratops (not too hard since they're allegedly "everywhere") with individuals of all ages, babies, juveniles, and "old adults" that we currently call Torosaurus. They have to be articulated and in the same layer, it has to be plausible that they all died together. Not finding Torosaurus babies isn't a valid excuse, babies of a rare species are even more rare in the fossil record - it doesn't prove "evidence of absence".
2. Find a transitional ontogenic stage that perfectly bridges the gap from Triceratops to Torosaurus. Not just in terms of the fenestrae, but also frill shape which is more "butterfly-ish" with Torosaurus.
3. Find a Torosaurus at least 50% complete that's conclusively bigger than every Triceratops known. This is more like "corroboration" that on its own proves nothing, but since dinosaurs keep growing slowly as they age, this would fit with the theory that Torosaurus was really an adult Triceratops. So far the biggest Triceratops have larger postcranial elements than all known (albeit fragmentary) Torosaurus specimens, which totally contradicts Horner's ultimate conclusion. Shockingly, Torosaurus is shorter than the biggest Triceratops by nearly 2m, and estimated to be lighter by as much as 50%.
4. Find a good reason why Torosaurus is so rare in the fossil record compared to Triceratops. If you're comparing Torosaurus to baby trikes I get it, but I don't know of a single reason why "adults" should be so much rarer than "juveniles" of similar or even larger size. Did predators really go for the 24-foot "mature adults" and leave only a handful to get fossilized? Or did they simply eat so many of the far more common (and larger and more well-armed) "juvenile" 30-foot giants that only an abnormally small percentage grew (or rather shrank) to adulthood? How can such grim odds be compatible with the overall survival and even extreme niche-dominance of Triceratops as a genus?
Knock out all four of these objectives and you'll be proven right. Otherwise there's miles of room for doubt and debate.
@ everyone:
Additional comment-
Aside from the possiblity that anatomical and histological analyses of bone tissues could result in the misclassification individuals of one taxon is there is no access to behavioral, ecological, and molecular evidence as members of another taxon, genetically close relatives can have radically different anatomical appearances from one another (such as in the case of hippos and whales).
I also believe that a dinosaur DNA bank is possible...only that it will take a long time (probably past the lifetimes of most people today).
@ Nima:
Dr. Andrew Farke also commented on a magazine article that in all known ceratopid genera, the number of eppocipitals present in pups is conserved throughout the animal's life. True, eppocipitals tend to become blunt in old adults, but their numbers are retained even in "granny" specimens. Since Triceratops and Eotriceratops are the only chasmosaurines that possess an eppocipital positioned at the parietal-sqamosal suture, I'm more inclined to believe that Eotriceratops, not Torosaurus, is the sister taxa of Triceratops.
That would be a pretty good guess, Hikaru.
One other thing that shocked me about this whole "Toroceratops" controversy (and makes Horner and Scanella's theory pretty off base to me) is the inconvenient fact of Nedoceratops (I still feel like saying Diceratops for some reason...)
Nedoceratops is a actually a pretty big specimen (the skull is around 2m long) but it has the rough proportions of one of the smaller Triceratops specimens. Of course large size doesn't prove maturity in Horner's book - apparently the opposite. But Nedo has the weirdest mix of conflicting features that simply don't fit anywhere in Horner's theory of extreme ontogeny.
1. Nedo has a relatively short frill by Triceratops standards. Like a juvenile animal. There are large Triceratops with considerably longer frills and yet more "juvenile-looking" double curved horns.
2. The horns curve forward - an adult trait according to the Horner camp. the horns lack the double curve characteristic of "young" triceratops or the upward curve found in juveniles.
3. Yet the horns are tilted up and back at an angle very similar to juveniles, a much more vertical angle than in any "adult" triceratops OR Torosaurus. This would look a lot like a juvenile Triceratops if the horns simply bowed the other way.
4. The frill is shaped differently from either species.
5. The bone reabsorption in the frill seems to fit with Horner's theory of adult Triceratops developing fenestrae later in life.
6. The epoccipitals on the frill are worn down but certainly not absent. There are some triceratops with more "juvenile" double curved horns which have a much larger frill and far more vestigial, almost non-existent epoccipitals.
7. The beak is long and low like Torosaurus, and also like Torosaurus the nasal horn is pretty much reabsorbed. Yet the snout behind the horn is a lot shorter than in Torosaurus and even most large Triceratops specimens.
8. The cheek spikes point straight down in Nedoceratops, whereas in both Triceratops and Torosaurus they are angled further back. Also Nedo's spikes seem to merge with the frill a lot more than in Torosaurus or Triceratops, there there's more of a "valley" cleanly separating the frill from the spike.
9. The little side holes in Nedo's frill are unusual. A few Torosaurus specimens have them, but not all (Marsh's two specimens seem to lack them). The holes are pretty rare in Triceratops as well.
Nedo is not some transitional ontogenic stage between the two. I'd conservatively keel app three as separate genera for now. Nedo is similar to both but obviously must have had an entirely different ontogeny pattern as it grew up. So far it looks like Eotriceratops is Triceratops's closest relative. Then you have Nedo a bit further out. And then perhaps Torosaurus.
Why is the concept that size is not a good proxy for ontogeny, difficult to grasp? Yes it works at very young ages, but we are not talking about very young animals. We are dealing with animals at or very near osteological maturity, at this stage trying to use size as a proxy for age is absolutely useless.
For starters, the maximum adult size as well as the rate at which they achieve their maximum size is subject to high degree of individual variation in ALL animals. This is the case regardless of whether and organism has indeterminate or determinate growth.
In addition to the genetic factors influencing an animals growth, there are also environmental factors to consider. The quality of food, stress all have an impact.
As a final example of why size does not equal age: I was taller than my father when I was 15 and he was 45, now I'm significantly taller.
@ everyone:
Just let me rephrase my earlier comment. I'm sorry for not checking the syntax beforehand.
Old:
Aside from the possiblity that anatomical and histological analyses of bone tissues could result in the misclassification individuals of one taxon is there is no access to behavioral, ecological, and molecular evidence as members of another taxon, genetically close relatives can have radically different anatomical appearances from one another (such as in the case of hippos and whales).
New:
Aside from the possiblity that anatomical and histological analyses of bone tissues could result in the misclassification of individuals of one taxon as members of another taxon if there is no access to behavioral, ecological, and molecular evidence, genetically close relatives can have radically different anatomical appearances from one another (such as in the case of hippos and whales).
Dear god.
But first, since I know my whales: whale dentaries are not diagnostic enough (in most cases: i.e. in assemblages with co-occuring confamilial taxa) to be identified to a species (or sometimes even genus) in low sample sizes. With larger sizes, it is possible based on length and cross-section, etc. That being said - this is only a convenient straw-man, anyway, because Scannella and Horner sectioned cranial elements from crania that could be positively identified as Triceratops or "Torosaurus" - you know, based on things like cranial morphology (which said taxa are diagnosed by).
I know there's an SVP embargo, but there is a presentation at SVP this year where Torosaurus and Triceratops squamosals are (GASP) found in the same bonebed.
WRT Triceratops being longer 'by 2m' and mass estimates being greater for Triceratops - that's a load of shit. There aren't any Triceratops OR "Torosaurus" skeletons complete enough to confidently make either estimate an arguable point. And as Christopher points out, size matters not. As humans we know there are tall people and short people. It's really, really obvious. Triceratops and Torosaurus overlap in size - that's not a problem, or really an arguable point to begin with, since the time component is a big ass "?".
And, lastly, it's just plain laughable that anyone is considering 'Nedoceratops' to be a valid taxon; most of the above cited features fall within the range of variation for Triceratops. Oddly enough, fenestrae in the squamosal are NOT held to be of phylogenetic significance for Triceratops, Arrhinoceratops, Torosaurus, or Utahceratops, and ONLY for Nedoceratops.
Lastly... I think molecular paleontology has a long road ahead until it is A) more than marginally accepted as valid or even real, let alone B) considered anywhere near reliable enough to be useful in phylogeny. I want to believe in it, and I know I'm utterly unqualified to make any sort of qualification about it, save that a lot of other folks who are qualified have cast doubt upon it. I'm not decided one way or the other, except that the criticisms of other specialists indicate there's a long, tough road to validity/utility.
Anyway, I highly recommend attending the meeting next week and seeing the talks, they might prove to be enlightening.
@ whale boy:
I completely agree with you that histology alone is not enough to discriminate between genus. Not just in whales. Even in primates, one can misclassify bones from an individual of one genus as belonging to that of another genus (if you have not seen these links before, you may check them out:http://onlinelibrary.wiley.com/doi/10.1111/j.1556-4029.2006.00368.x/abstract; http://onlinelibrary.wiley.com/doi/10.1002/ar.10055/full).
Second,the observable physical anatomy of an animal is influenced by both the genetic composition and the environmental conditions of an animal.
About the parietal bones of the two taxa being found in one bonebed, those bones alone are not enough to tell that the two are the same genus. A more convincing evidence is if they could find a bonebed where both Triceratops and Torosaurus skeletons are found together in one locality and with those skeletons being relatively articulated.
Fourth, biomolecular examinations (i.e. ancient DNA analyses) are indeed difficult and still have quite a big room for improvement, but still possible, given the current technology advancement rate that our society experiences. As for Horner, what i like about him is that both of us believe that anatomical, histological, and ecological evidence analyses should be verified using bio-molecular examinations. That's why I have been asking and waiting for more evidence, especially molecular examinations (even if the only DNA they could extract from those animals is mitochondrial DNA since it is more stable than nuclear DNA but have a disadvantage of being inherited only from an individual's maternal line).
Hikaru,
Taphonomically speaking, a bonebed containing articulated skeletons of both "taxa" isn't going to tell you anything more than a bonebed containing articulated skeletons. All an articulated skeleton tells you is that all the bones of one carcass were buried together; it does NOT indicate that the individuals were living together (carcasses can float for hundreds of miles downriver, and out to sea) at the time of death (or, that they were even living contemporaneously in the same area, given the time-averaging associated with bonebeds). Anyway, I was mentioning this because that was one of Nima's requests that's already been fulfilled (most of them have).
@Hikaru
"I completely agree with you that histology alone is not enough to discriminate between genus. Not just in whales. Even in primates, one can misclassify bones from an individual of one genus as belonging to that of another genus"
Have you even read the Scanella and Horner paper? Your argument smacks of someone who has not. I'll say this again, the histology is NOT being used to differentiate species/genus/family/whatever else. Its ONLY being used to identify the state of growth and thus to infer the ontogeny of the specimens.
"Fourth, biomolecular examinations (i.e. ancient DNA analyses) are indeed difficult and still have quite a big room for improvement, but still possible, given the current technology advancement rate that our society experiences."
It doesn't matter how far or fast our technology advances. You need to be able to find DNA older than 800,000 years first. The Greenland specimens had the advantage of being frozen in permafrost, there is much older fossil DNA, but again it was preserved inside salt crystals. Regardless of our technological ability, there are limitations that can just not be overcome.
@ Whale Boy:
"Taphonomically speaking, a bonebed containing articulated skeletons of both "taxa" isn't going to tell you anything more than a bonebed containing articulated skeletons. All an articulated skeleton tells you is that all the bones of one carcass were buried together; it does NOT indicate that the individuals were living together"
For one, I agree that a bonebed containing intact skeletons of both taxa is not truly reliable to tell one that they lived together as a herd. That's why the surrounding sediments must be examined for the possibility that they might have been reworked (being coincidentally buried in the same locality due to environmental influences such as floods or droughts, scattering of of other animals, or just happened to have been buried in that spot) in that burial.
@ Christopher:
"...the histology is NOT being used to differentiate species/genus/family/whatever else. Its ONLY being used to identify the state of growth and thus to infer the ontogeny of the specimens."
I have answered this point before: demonstrate that Triceratops had not undergone paedomorphosis (a developmental process in which juvenile traits of the ancestor taxon are retained in adults of the descendant taxon due to gene expression control)in its evolution because if that is the case, that could explain why the tissue structures of the crest bones and horn cores of Triceratops appear "immature" compared to Torosaurus. Hence, ontogenic stages inferred in those animals' histological analysis could turn out to be superficial if a paedomorphosis mechanism (i.e. progenesis, neoteny) occured in Triceratops(I know that some centrosaurine juveniles have solid, yet thin crests as youngsters; however, this is not yet ascertained in the juveniles of ancestral chasmosaurines).
"It doesn't matter how far or fast our technology advances. You need to be able to find DNA older than 800,000 years first...."
That's why I am waiting for more fossil evidence. Who knows? Maybe someday scientists could find "mummified" Triceratops specimens (it does not matter if its T. horridus or T. prorsus, but it's better if mummified fossils of both species could be discovered as to resolve the issue if the two are indeed separate species). Also, I have once watched Dr. Horner in a Discovery Channel interview in which he says that finding dinosaur fossils that have DNA preserved in them is possible. And mummified specimens, according to others, could be the best fossils that harbor the best preserved dinosaur DNA. So do not say that finding fossilized DNA is impossible. Based on Dr. Horner's advocacy, molecular analyses will be needed to truly resolve the issue of the two animals'.
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