Sapient Cenozoic deinonychosaurs

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Vladimír Socha

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May 27, 2026, 11:40:25 AM (10 days ago) May 27
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Good day! I wonder, could dinosaurs have evolved a similar level of intelligence to advanced primates if they hadn’t been wiped out 66 million years ago? We know that deinonychosaur (troodontid and dromaeosaurid) theropod dinosaurs from the last 15 million years of the Cretaceous period developed still bigger brains and higher intelligence. The smartest ones are usually thought to be the troodontids with EQ values of up to 6.48. Troodontids became extinct at the time when their neurocrania were still developing and growing. What if they had another 10 or 50 million years of evolution ahead? We now know that these dinosaurs were smarter than all recent reptiles but probably not as intelligent as very smart birds or monkeys, as some researches suggested. But still, is there something that could have prevented troodontids from becoming a sapient or at least highly intelligent beings during the Paleogene and/or Neogene?

Also, how would you answer this question: Why didn't non-avian dinosaurs evolve into intelligent species during the 170 million years of their existence, but then it took only 66 million years for other species to evolve into highly intelligent being?

Refs:


Russell, D. A. (1997). Intelligence. In Kevin Padian; Philip J. Currie (eds). Encyclopedia of dinosaurs. San Diego: Academic Press. pp. 370–372.

Larsson, H. C. E. (2001). Endocranial anatomy of Carcharodontosaurus saharicus (Theropoda: Allosauroidea) and its implications for theropod brain evolution. In: Mesozoic vertebrate life, eds. Tanke, D. H.; Carpenter, K.; Skrepnick, M. W. Indiana University Press, 19–33.


Tristan Stock

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May 27, 2026, 12:14:00 PM (10 days ago) May 27
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Evolution by natural selection doesn’t have end goals, it just works with what’s advantageous in the moment. There’s no reason why higher cognitive capabilities had to evolve during the Mesozoic, nor why it we would need to occur after a hypothetical no-K/Pg event timeline. Earth life was just fine for 3 billion years without becoming multicellular, just like how there was no guarantee that life would become multicellular again if you rerolled “progress” back to the Archean and watched.

As for if they could’ve done so: they already did.
Psittacopasserae is a dinosaur clade often characterized by large brains, advanced cognitive abilities, and complex social behaviors comparable to advanced primates, and it includes the majority of extant dinosaurs. There’s also some growing evidence that their sister group the Falconiformes is comparatively brainy with similar cognitive abilities, as well as the more distantly related Bucerotidae, with both groups now passing cognitive tests designed for human children. Bucorvus ground hornbills even had an evolutionary radiation comparable to humans, being ancestrally forest-dwelling arboreal frugivores that became terrestrial-adapted social open habitat omnivores with the spread of arid conditions in Africa that also triggered the radiation of Australopithecines and early genus Homo. They are what actually happens when nature tries to make a Russel-Seguin style Dinosauroid.

Relevant reading. Running about, otherwise would format properly:




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Tristan Stock

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May 27, 2026, 2:28:09 PM (10 days ago) May 27
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Not sure why my second paragraph turned invisible after posting. Here it is corrected for people to see:

As for if they could’ve done so: they already did. Psittacopasserae is a dinosaur clade often characterized by large brains, advanced cognitive abilities, and complex social behaviors comparable to advanced primates, and it includes the majority of extant dinosaurs. There’s also some growing evidence that their sister group the Falconiformes is comparatively brainy with similar cognitive abilities, as well as the more distantly related Bucerotidae, with both groups now passing cognitive tests designed for human children. Bucorvus ground hornbills even had an evolutionary radiation comparable to humans, being ancestrally forest-dwelling arboreal frugivores that became terrestrial-adapted social open habitat omnivores with the spread of arid conditions in Africa that also triggered the radiation of Australopithecines and early genus Homo. They are what actually happens when nature tries to make a Russell and Séguin-style Dinosauroid that's copying humans.

Relevant reading:

Dawid Mazurek

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May 27, 2026, 4:55:07 PM (10 days ago) May 27
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"only 66 million years for other species to evolve into highly intelligent being".
There are no known verebrate species living today, that old. On the other hand, ancestors of every species, whether considered intelligent or not, have been evolving since Precambrian.
Dawid



Thomas Yazbek

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May 27, 2026, 4:55:15 PM (10 days ago) May 27
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Evolution is contingent, and intelligence is embodied, not simply a matter of how big your brain can get. Humans are the most intelligent because of our 'evolutionary baggage' or lack thereof: our dextrous, flat-nailed, 5-fingered hands, our typically mammalian facial musculature, and our throwing abilities owing to our anatomy. Toothless beaks probably help birds be more sapient than their toothy theropod ancestors, but the lack of hands is a liability, and it's not like theropod forelimbs were super useful to begin with. Birds that need to fly are also severely limited in terms of size and strength, which also means that they have 'baggage' to overcome (dextrous humans weighing ~100-200 lbs are able to kill large, protein-rich mammals, modify the environment very significantly, and wield fire). 

FWIW, I am definitely more and more impressed by the cognitive capacity of advanced birds, they certainly have a lot of things that other 'smart' mammals don't. But I think that the human body plan is just less limiting. 

Brad McFeeters

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May 28, 2026, 7:05:45 AM (9 days ago) May 28
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Do we know this? Deinonychosaurs have a fossil record spanning about 80 million years, and I haven't heard of anyone showing that the later ones were brainier than the early ones.

Javier Castro Terol

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May 28, 2026, 10:28:46 AM (9 days ago) May 28
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What is the evidence that they were still growing and developing their neurocrania? Seems difficult to state something like that. Apart from that, in a similar way that many of the answers, it seems to me that the trend of evolving more intelligent forms is presumably as possible as the opposite. Evolution is contingent. Even without a mass extinction, knowing the trajectories this group could have taken in a always changing conditions is basically impossible.

JCT

El 28 may 2026, a las 13:07, Brad McFeeters <bradleyd...@gmail.com> escribió:

Do we know this? Deinonychosaurs have a fossil record spanning about 80 million years, and I haven't heard of anyone showing that the later ones were brainier than the early ones.


On Wednesday, May 27, 2026 at 11:40:25 AM UTC-4 Vladimír Socha wrote:
We know that deinonychosaur (troodontid and dromaeosaurid) theropod dinosaurs from the last 15 million years of the Cretaceous period developed still bigger brains and higher intelligence.

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