What on Earth Was Herrerasaurus?

The early evolution of dinosaurs is the subject of much debate, and one dinosaur in particular has allowed a remarkable glimpse into the early diversification of the group, while also being situated in the centre of a fascinating debate - Herrerasaurus ischigualastensis.

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[cliveroberts]

Amazing to think the time span between Herrerasaurus and T-Rex is 2.5 times longer than between today and T-Rex

[richardikin]

When I was a child I was obsessed with dinosaurs and knew pretty much everything about them. Now I'm 58 and it seems that the world of dinosaur palaeontology has moved on so far that I now know very little.

[yissibiiyte]

Heterodontosaurus is another dinosaur with a similarly murky phylogenetic history. A video on it would also be nice

[rockmuncher_]

fascinating. the triassic is often overlooked, glad to see some love for that time

[Pipkiablo]

Science: "What are you?"
Herrerasaurus: "I don't know! You keep confusing me!"

[tylociraptor]

Glad to see my favorite rectangle headed goofball getting some love! YEAH HERRERASAURUS!

[yissibiiyte]

As someone who gets all my phylogenetic knowledge from Wikipedia, I've often wondered this question

[alicehargest]

I love that you link your sources not enough channels do this!

[fermintenava]

Thank you for a video on that subject! Early dinosaurs are very underrated, and a video on other dinosauromorpha/groups of archsaurs would be a great companion piece to this.

[Cat_Woods]

I'm always astounded at these discoveries that sat in a drawer or storage for decades before someone finally noticed what they were. I don't know why, but I always expect science to be better organized than that. If I could go back in time, I'd make it a project to get universities to inventory all their collections, catalog the identifying details, and publish these catalogs once a year in a journal dedicated to this purpose. Or at least once a decade.

[zddxddyddw]

Thank you for bringing attention to Argentine palaeontology! It is really underrated and has produced so much important information about the evolutionary history of life on Earth.

[metalliphil]

The uncredited sculpture in your opening montage appears to be a Stephen Czerkas sculpture — a whole video about the Argentinian Carnian age fauna would be an interesting video that would fit in well with this one

[alanfenick]

You dedication to teach is very evident by your preparation and presentation! I love a professor/instructor with such enthusiasm so lacking in some classrooms!

[johnelliott]

I remember reading about this animal some years ago, so your video has been most welcome.

[sahb]

I've long looked at this question, because it is one of my favourite dinosaur fossils with the number of its digits alone! Strange that with all we know, we don't really know this. Exciting topic.

[ThePalaeontologist]

The rapid radiation of relatively basal (by Dinosaurian standards) aka 'primitive' Herrerasaurids could have something to do with the Carnian Pluvial Event/Episode (or Carnian Humid Event/Episode) from ~234-232 Ma. They are already rather beautifully advanced in form as compared to numerous other Archosaurs from the Triassic Period, even as far back as 233 Ma. Which is to say, they were already looking pretty developed even by the mid Carnian Age.

However, there had been a considerable propensity for a long time in Palaeontology, for many creatures we'd now consider to be related Archosaurian Dinosauromorphs, rather than true Dinosaurs, to be simply referred to as Dinosaurs. This continued to cause confusion as in reality, no true Dinosaurs were definitively known from before about 225 million years ago, that is, until the likes of Herrerasaurus and Eoraptor came to light. Now we know the Dinosaurs were at least 233 million years old, and likely a few million years at least, older than that. There are more recently claims of South African and Malagasy (Madagascan) fossils to stretch back into the Ladinian Age, and some even claiming Anisian. Which in other words, means Dinosaurs over 240-245 Ma. Which, I do not adhere to.

This seems dubious in my view, as I'd argue true Dinosaurs likely did evolve from Dinosauromorph Archosauromorph Archosaurs, around the early Carnian Age (although I am not going to reject the idea of a Ladinian Age true Dinosaur, it would not necessarily have enough of the diagnostic characteristics of a true Dinosaur, and more likely demonstrate another transition fossil species on the way to something more like a true Dinosaur) For an example of this matter, the Dinosauromorph known as Saltopus, was long considered to be a Dinosaur in many books for years, until it was gradually realised to be slightly too primitive to fit the diagnostic description of one, anatomically.

In a sense, what is attempted in the pursuit of the earliest Dinosaurs, in a taphonomically fraught fossil record, is the search for 'Dinosaur Zero'. And good luck with that; because finding the exact earliest origin point of Dinosaurs, is of course going to be tough. Necessarily, it will be borderline so primitive by Dinosaurian standards, as so to be scarcely discernible from out of a myriad of closely related Dinosauromorph kin and likely direct progenitors.

When and where this happened isn't exactly known, though can be inferred quite reasonably to the Carnian Age in general, though with potential Ladinian Age origins. That said, we have a strong idea that it may have been more likely Dinosaurs evolved first in what was then Southern (or maybe even more accurately South-Western) Pangaea.

Geographical boundaries would have slowed Dinosaur radiation into the Northern Hemisphere as well as there being a range of well-established Archosaurs and Therapsids already there (not to mention various other reptiles and the more ancient Temnospondyl Amphibians) Yes, all of these also lived in the South, though conditions at places like Santa Maria and Ischigualasto (i.e. Carnian Triassic Brazil and Argentina, in Southern Pangaea) were very conducive to the rise of the early Dinosaurs, for whichever reasons.

The significance of the Carnian Pluvial Episode, is that it saw heavier precipitation, and humidity, allowing for plentiful wetland and monsoonal like river systems with sweltering conditions under the Triassic Sun and the Carnian thunder. They were well-watered with abundant river channels and wetlands, giving a very different look to the often considered completely barren Triassic, than has often been realised. It has been more well-understood since the matter came into scientific debate from 1989 onward, and although there is still some dispute on how things happened in more depth, the Carnian Pluvial Episode is still generally considered an important aspect of the potential acceleration of Dinosaur evolution.

Dinosaurs were more water efficient to begin with, and had their classic physical advantage of walking with their limbs aligned beneath their bodies and not in a less energy efficient sprawling gait. During the Carnian, the conditions were very rainy and this may well have made places like Santa Maria, a perfect testbed for the then new Dinosaurs to flourish. Speculatively one might argue that some Dinosaurs had their first starts in places where Dinosaurs could be even more important palaeoecologically. Conditions were still generally hot and dry across the Triassic, with conditions getting much drier again in the Norian Age, though it is possible the Carnian Pluvial Episode helped them in their early days.

[Harrysof_]

Believe it or not, i came from jurassic park the game (2011) because this dinosaur seemed so weird to me since i never seen it before, great video by the way👍

[TribbleArtCreations]

That was a lot deeper dive than I anticipated. That said, I really appreciated it. I think I underestimated the crazy history it has.

[edureal]

Hi Ben, what about a video about ammonites?

[kurtoogle]

Man, Ben has gotten so damn good at this!! Well done, sir!