When 2 dinosaurs become 1


Prepare to have your mind blown.

Certain dinosaurs—physically disparate enough that we've always thought of them as different species—may actually be the same animal at different stages of its life cycle. Also: Those big, protective-looking bone formations surrounding some dinos' heads and necks probably weren't all that useful as a defense against predators.

Case in point, triceratops. Or, maybe we should be calling it torosaurus now, I'm not sure. See, according to research done by scientists at Montana's Museum of the Rockies, the familiar triceratops is really just the juvenile form of the more-elaborately be-frilled and be-horned torosaurus.

This extreme shape-shifting was possible because the bone tissue in the frill and horns stayed immature, spongy and riddled with blood vessels, never fully hardening into solid bone as happens in most animals during early adulthood. The only modern animal known to do anything similar is the cassowary, descended from the dinosaurs, which develops a large spongy crest when its skull is about 80 per cent fully grown.

Scannella and Horner examined 29 triceratops skulls and nine torosaurus skulls, mostly from the late-Cretaceous Hell Creek formation in Montana. The triceratops skulls were between 0.5 and 2 metres long. By counting growth lines in the bones, not unlike tree rings, they have shown clearly that the skulls come from animals of different ages, from juveniles to young adults. Torosaurus fossils are much rarer, 2 to 3 metres long and, crucially, only adult specimens have ever been found. The duo say there is a clear transition from triceratops into torosaurus as the animals grow older. For example, the oldest specimens of triceratops show a marked thinning of the bone where torosaurus has holes, suggesting they are in the process of becoming fenestrated.

There are other species this might apply to, as well. Some with even bigger shifts in appearance.

While this is a Big Hairy Deal for dinosaur science, it also elicits a little bit of a "duh" moment when you go back and look at the animals in question. What you should really be getting out of this story is an illustration of how difficult it is to study a creature that's been extinct for millions of years.

After all—as my husband pointed out—nobody would be shocked to learn that a baby chick, an adult chicken, and plate of parmigiana were all the same animal. But that's because we've experienced chickens. Were an alien to drop in on Earth for one afternoon, they might be just as amazed at the life cycle of poultry as we are now at the triceratops/torosaurus'. Paleontologists are tasked with reconstructing the lives of animals nobody has ever seen alive. And that creates a world where the obvious just isn't.

New Scientist: Morph-o-saurs: How shape-shifting dinosaurs deceived us

(Via John Taylor Williams)

Image courtesy Flickr user lindseywb, via CC


  1. So extinct insects would really trick these poor scientists. Caterpillar? Butterfly? How could those be the same species?

  2. Like with Apatosaurus/Brontosaurus, the first named example wins out. So it’ll be Triceratops.

  3. What?
    TRICERATOPS is evolving!

    Congratulations! You TRICERATOPS evolved into TOROSAURUS!

  4. A tadpole and a frog. A caterpillar and a butterfly. Yeah, I wonder if metamorphosis wouldn’t be totally unheard of on other planets, too.

  5. Many people in long-term relationships experience this confusion and disbelief regarding the life stages of spouses.

    1. Speaking of spouses, mine didn’t know the yellow flower weeds and white puffy flying seed weeds were both the same thing (dandelions) until she was in her thirties :)

  6. So, how will this affect things with regards to the Blue Mighty Morphin’ Power Ranger?

  7. Thankfully it looks like we’ll avoid another Brontosaurus -> Apatosaurus debacle on this one. A quick check shows that Triceratops is the older name, so Torosaurus is headed for the dustbin of history if this gains wide acceptance.

  8. So at what elevation do triceratops turn into torosaurus? (Or is that a seasonal issue?) :-P

  9. We paleontologists follow fads of lumping and splitting species names. Scannella and Horner’s paper does an excellent job of illustrating ontonogenetic series of a ceratopsian, but come to the conclusion that Triceratops changed morphology very rapidly, very late in development. The Torosaurus morphology is much rarer, and it stands to reason that breeding age individuals were not the minority. Therefore, either Triceratops underwent this transformation after reaching breeding age, there are two sexes of the same species and males underwent late changes for stronger mate competition or there are two different species with similar early life stages. I think that the last is the correct hypothesis. Scannella and Horner illustrate an ontonogenetic series of 11 frills. I see two distinct size series within their one ontonogenetic series with the distinct morphologies. It seems likely that we’ve been calling too many of the baby dinosaurs Triceratops when some of them were probably Torosaurus. This would be like confusing a young chicken and a young guinea foul. When more research is done into the fine detailed differences between individuals, I think it is likely that we’ll come up with more ways of differentiating the two and Torosaurus will be considered distinct again.

    1. So, two different species in the same place at the same time, extremely hard to distinguish until they reach old age? Scannella and Horner suggest it but dismiss it as a less parsimonious explanation, which sounds more reasonable to my ears (though I am no palaeontologist).

    2. Or, the young of the species were more likely to walk into tar pits or get stuck in the mud in a river, whereas the ones who were smart enough to avoid that fate died of old age under a shrubbery somewhere and their bones never fossilized. You can’t assume that the number of fossilized remains is proportional to the number of living creatures. We Engineers get fooled less often than Paleontologists.

    1. wouldn’t genetic testing settle it?

      You can’t extract DNA from a fossil.

  10. wouldn’t genetic testing settle it?

    A superlative suggestion sir, with only two minor drawbacks: one, we don’t have any dino dna and two, we don’t have any dino dna. I know that technically that’s only one drawback, but I thought it was such a big one it was worth mentioning twice.

    1. Piffle. I saw a documentary a few years back about scientists obtaining dinosaur DNA from insects trapped in amber. I think that it was filmed on an island off Costa Rica.

  11. I had the following thought in a museum a few years ago: maybe the arms of Tyrannosaurus rex are not evolutionarily vestigial, but rather developmentally vestigial.

    If you imagine a T. rex growing from a much smaller egg, at some point you would have a dinosaur about the size of a Velociraptor. It *could* be shaped exactly like a T. rex and go around biting things, but it seems like it would do much better for itself if its arms were proportionally longer and more useful, and it looked and acted more or less like a Velociraptor. (I.e., scratching and disemboweling its prey rather than simply grabbing it with the head.)

    As it got bigger and bigger, my theory goes, its arms would not grow as much as the rest of it, leaving it with tiny useless arms when it got to full size. I think the hormonal system could make such a selective growth happen.

    1. Some of the earliest recognizable tyrannosaurid ancestors from China did have long raptor like arms. While a smaller t-rex with proportionately bigger arms would be cool, there have been a number of very young tyrannosaur fossils found and they still have puny arms, and actually proportionately longer legs instead. Since tyrannosaur bonebeds often contain individuals of all age classes, we now think that they probably hunted as a family group, with fleet footed youngsters running prey down and super powerful adults bitting prey like it was getting hit by a buick with teeth.

  12. After all—as my husband pointed out—nobody would be shocked to learn that a baby chick, an adult chicken, and plate of parmigiana were all the same animal.

    In the US that may be true, but if you try telling an Italian that parmigiana contains chicken, don’t be surprised if the response involves torches and pitchforks.

  13. How can you see growth rings on the bones when they’ve been replaced by minerals? Does someone have some real bone skulls they’ve been holding out on? I thought they were all fossils.

  14. Jesus turned triceratops into torosaurases with a wiggle of his nose. All praise my invisable friend in the sky

    1. I think that they’re referring to fossilized soft tissue, although the article is vague.

      1. @#41 You haven’t seen the Nova episode? http://www.pbs.org/wgbh/nova/sciencenow/3411/01.html She first spotted what looked like red blood cells. Then her assistant demineralized the sample and it was squishy and resilient.

        Oh, though they concentrate on the T-Rex in the video, they also got soft tissue from a Triceratops and a Duckbill that were even older.

  15. This is nothing new. I seem to remember that one of the EARLY FAMOUS dino investigators went around creating 2 species from 1. He found he got more attention and money if found a NEW species instead of a variation of a previously known species. So he would declare almost every new site a new species. The real scientists since have been reversing his ‘work.’

  16. Cf. baby and adult eels. The juveniles look like silver leafs, and ichthyologists didn’t know what they grew into. They also didn’t know what a juvenile eel looked like. SCIENCE!!!

  17. While we have bits of dino DNA, mostly from those insects trapped in amber, it’s like having a picture puzzle of a forest where most of the pieces are missing. There’s no way you can guess what the leaves on all those missing pieces would look like. In other words, we’re nowhere close to being able to clone a dino.

    As for the theory on Triceratops being a Torosaurus, it’s cool. Horner is the guy who first theorized that T-rex wasn’t a predator but a scavenger. But then you have a guy like Bakker who totally refutes that. So I think it’s premature to say definitely that it is so. But it’s definitely a pretty cool idea.

    Oh, and as for that T-rex “soft tissue”– it was proved to be a mistake three years later. There was no soft tissue inside a 65 million year-old bone.

  18. I think Triceratops was described first and then Torosaurus–by a couple of years. If the two species become synonymized, then the rules of zoological binomial nomenclature demand that Torosaurus, not Triceratops disappears. Translation: Torosaurus is really a Triceratops, not the other way around. Of course, there are alot of other possibilities–like that there are juveniles of two different species. Horner is famous for sensationalism and over-reaching conclusions with meager data, but that’s another story. Long live Triceratops.

  19. BoingBoing, I just want to thank you for not presenting this story as “Triceratops Never Existed!” the way pretty much every other news source is doing.

  20. In cases like this, when a name must be changed or eliminated, the older name takes precedence. O.C. Marsh named both Triceratops, and Torosaurus — Triceratops in 1889, and Torosaurus in 1891. So, the correct name would be Triceratops for all, and there would no longer be a Torosaurus (unless they recycle names and someone else uses it for a new dinosaur later on down the road).

  21. Sounds like some one found the shard. The urRu and the Skeksis are about to be rejoined.

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