Is the rise of meat-eating dinosaurs complicated?

No.
A Smithsonianmag.com writer is trying to make the ordinary extraordinary by claiming, “The Rise of Meat-Eating Dinosaurs Is More Complicated Than We Thought. “

Figure 1. Herrerasaurus from Black 2020. This is a basal dinosaurs. This is not an omnivore.

Figure 1. Herrerasaurus from Black 2020. This is a basal dinosaurs. This is not an omnivore.

Writer Riley Black (formerly Brian Switek)
writing in smithsonianmag.com declares: “The earliest dinosaurs arose about 235 million years ago during the Middle Triassic. They didn’t look much like modern favorites Triceratops or Spinosaurus. Instead, these lanky creatures didn’t get much bigger than a German shepherd. The current spate of evidence suggests they were omnivorous.”

Black also provides this image (Fig. 1) of middle Triassic Herrerasaurus, the basalmost dinosaur in the large reptile tree (LRT, 1688+ taxa) and this is no omnivore. This taxon is 3 meters or 16 feet long, not the size of a German shepherd.

Black continues:
“Up until now, paleontologists thought theropods remained generally small and on the ecological sidelines from about 235 through 201 million years ago. It was only after a mass extinction at the end of the Triassic, at the 201 million-year mark, that carnivorous dinosaurs started to get big. But that view is starting to change thanks to a new reading of the bone trail by scientists who think large meat-eaters may have appeared much earlier. Virginia Tech paleontologist Christopher Griffin says a key player in this story is Herrerasaurus.”

Confused?  So am I. This brings us back to where the LRT starts, regarding dinosaurs. Everyone in paleo knows Herrerasaurus is a Middle Triassic carnivorous dinosaur. The little German shepherd-sized dinos are either made up or never existed. In either case, Black doesn’t list or illustrate them.

Black continues:
“The known carnivorous dinosaurs during the later part of the Triassic appeared to be smaller and less imposing than the crocodile relatives they lived alongside (such as Postosuchus from the southwestern United States). Thanks to a better understanding of dinosaur growth, however, paleontologists have found that some of those little theropods were hiding a secret.”

Postosuchus is not a crocodile relative in the LRT. Herrerasaurus is closer to crocodiles in the LRT because only crocodylomorphs and dinosaurs make up the clade Archosauria.

Black continues:
“The few remains we’ve found of larger Triassic theropods come exclusively from immature animals that are still growing rapidly,” Griffin says. These young carnivores would have grown to lengths exceeding 18 feet in adulthood. That’s a little less than half a full-grown T. rex, but enough to make you want to avoid meeting such a carnivore face-to-face.”

A few Late Triassic theropod lengths: Tawa is 2m long. Coelophysis is 3m long. Both are represented by adult skeletons. Again, where are these imaginary few remains?

Black finally raises the curtain on her main attraction:
“Late last year, Ludwig-Maximilian University of Munich paleontologist Oliver Rauhut and colleague Diego Pol named an exceptional skeleton of a Middle Jurassic carnivore they called Asfaltovenator. This was a large animal, more than 25 feet long, that approached the average size of the later Allosaurus and bears more a passing resemblance to the later dinosaur.”

This is no big deal. Between the Late Triassic and the Late Jurassic we expect to find theropod dinosaurs bigger than their ancestors and smaller than their descendants with transitional morphologies.

Black concludes with a quote: 
“There is much more to be learned about theropod evolution during this time,” Rauhut says, with finds like Asfaltovenator hinting at what remains to be uncovered.”

Again, no big deal. There is always ‘much more to be learned’ about all taxa ‘during this time.’ Some people complain because I was a journalism major. Sometimes that degree comes in handy.


References
Black R 2020. The Rise of Meat-Eating Dinosaurs Is More Complicated Than We Thought. online here.

6 thoughts on “Is the rise of meat-eating dinosaurs complicated?

  1. Just a quick note: The largest specimen of Herrerasaurus (“Frenguelisaurus” PVSJ 53) could reach 6 meters in length, it was already large 231 Mya

  2. I fear the mistakes are not on the author’s side but are simply due to you omitting large bunches of her text and your incomplete knowledge on Triassic carnivores.

    No one claimed for Herrerasaurus being a Middle Triassic omnivore or German shepherd sized (ironically, despite what “everyone in paleo knows” the Carnian is a Late Triassic age and the theropod affinities of Herrerasaurus are still up for debate).

    The claim of potential subadult specimens refers likely to taxa like Liliensternus.

    Cheers.

    • A journalist has the responsibility during a compare and contrast article to include both categories. A journalist also has the responsibility to describe a subject clearly and without confusion. You are welcome to show us pertinent text that resolves the issues raised. Like Riley Black, you have, so far, left that vague. To your last point, according to Wikipedia Liliensternus is “5.15 m (16.9 ft) long”, so you’ll need to come up with a better guess into the mind of Mx. Black.

      • Well, I understood the article pretty well and I’m not even a native speaker. All your points argue against claims never made by Black or are against paragraphs taken out of context.

        Nowhere in the text is a connection drawn between Herrerasaurus and “Middle Triassic omnivore” or “German shepherd sized”. Instead, it is literally written that it is a polar bear sized carnivore. Apart from the fact that Herrerasaurus is Carnian, and hence Late Triassic in age. It is a whole paragraph dedicated to this taxon.

        Yes, the syntypes have been estimated to be this size and have been intrepreted to be also subadults. It is even cited in the Wikipedia article.

        The size of Asfaltovenator isn’t the key message. You’re just leaving out tons of text. It looks like you just picked a random paragraph from the text to argue against it. I somehow have the feeling you just want “mainstream” authors to be wrong.

      • Is the rise of meat-eating dinosaurs complicated? No.
        Are basal dinosaurs German shepherd size? No.
        Are Middle Triassic dinosaurs omnivores? No.
        The connection between Middle Triassic omnivore and German shepherd size dinosaurs and Herrerasaurus was made by the author because no other dinosaurs are mentioned and Herrerasaurus is a basal dinosaur, the only basal dinosaur mentioned and pictured.
        After being in this business for several decades, you will also be able to see what is NOT included that should be.
        I hope this helps. BTW, you’re doing great for a non-native speaker.

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