New Research Questions Hypotheses About Climate-Controlled Ecosystem Change During the Origin of Dinosaurs in Argentina

Peer-Reviewed Publication


Ischigualasto formation ecosystem reconstruction

A group of researchers from CONICET and the University of Utah demonstrated that during the time of the first dinosaurs, variations in the diversity and abundance of the plant and vertebrate animal species cannot be related to the climatic changes recorded throughout its deposition, in contrast with previous hypotheses.

In the new study, published in the open access journal Frontiers in Earth Science, the team of scientists investigated multiple independent lines of evidence (sedimentology, clay mineralogy, and geochemistry) to elucidate changes paleoclimatic conditions (such as mean annual precipitation and mean annual temperature) within the Ischigualasto Formation. These fossil-rich sedimentary rocks were deposited by rivers and streams between ~231 and 226 million years ago during the Late Triassic Period in what is now northwestern Argentina (La Rioja and San Juan provinces). In the middle of the formation, the researchers observed a clear change in conditions approximately from warmer, drier conditions to more temperate humid conditions, but no concurrent major changes could be identified in the fossil record.

“We conclude that variations in the abundance and diversity of species, as recorded by their first and last appearances in the fossil record, are better explained by preservation and sampling biases biases than by changes in climate,” said Adriana Mancuso, lead author and CONICET independent researcher at the Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales in Mendoza, Argentina.

“What we see is that how many specimens collected from each interval of the sequence, and the chemical & physical characteristics that allow greater or lesser preservation of the remains of animals and plants, were significant factors. These two factors, collection and preservation, have more influence on the increase or decrease of abundance and diversity than the climate changes recorded,” explained Mancuso.

However, although the evolution of the ecosystem does not generally show a biotic response associated with climate change, the research group did observe a relationship between climatic variations and two groups of reptiles, rhynchosaurs (herbivorous early archosauromorphs) and pseudosuchians (crocodilian-line archosaurs). “We did find that the abundance of rhynchosaurs and extinction of a few pseudosuchian species appear to coincide with a climate shift,” said Randall Irmis, co-author from the U and the Natural History Museum of Utah.

Beyond conclusions about this specific fossil and paleoclimate record from Argentina, the new research emphasizes the importance of an explicit framework for testing hypotheses about the link between climatic changes and the fossil record. “In addition to the contribution on the relationship of biotic and climatic events in the Ischigualasto Formation, the work provides a methodological framework to test climate-biota associations, highlighting the data gaps that must be filled, and makes new testable predictions that can be tested in future studies,” concludes Mancuso.

Other authors include Tomás Pedernera and Cecilia Benavente of the Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (CONICET), Leandro Gaetano from the Instituto de Estudios Andinos (CONICET) and Departamento de Ciencias Geológicas of the Universidad de Buenos Aires, and Benjamin Breeden of the University of Utah.


Frontiers in Earth Science




Observational study


Not applicable


Paleoenvironmental and biotic changes in the Late Triassic of Argentina: testing hypotheses of abiotic forcing at the basin scale.



From EurekAlert!

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dodgy geezer
June 13, 2022 2:09 pm

Obviously the Rhynchosaurs stopped the
Pseudosucharins from using all those pick-up trucks, and the climate became colder…. which eventually killed them all off.

We are going the same way. If we were able to drop CO2 down to below 300ppm, our agricultural yields would plummet, with many dying from starvation…

Reply to  dodgy geezer
June 13, 2022 6:29 pm

No need for low CO2. Our politicians will have a few billion people starving to death in no time flat.

Why should they wait for Climate Change™ to do it? It takes too long anyhow.

C’mon now, gang. Let’s get this Socialist Sh!t Show on the road already! Time’s a wastin’.

jeff corbin
Reply to  H.R.
June 14, 2022 2:04 pm

Ain’t that right!!

John Tillman
Reply to  dodgy geezer
June 14, 2022 5:36 pm

Dinosaurs were already gaining ground against synapsids (reptile-like mammal relatives) and other archosaurs, ie dino relatives. But the end Triassic mass extinction cleared the scene for rapid dino evolution.

Ed Zuiderwijk
June 13, 2022 2:10 pm

Do I get this correctly that the authors say that you can’t deduce climate change from the fossil record because the fossil record is too much affected by sampling biases?

Reply to  Ed Zuiderwijk
June 13, 2022 2:25 pm

The way I understood it is you cannot determine the effect of a climate change on vertebrates based on the fossil record because of the changes in conditions conducive to fossilization resulting from a climate change.

IOW certain conditions of climate are more conducive for fossilization than others.

Richard Page
Reply to  Ed Zuiderwijk
June 13, 2022 2:37 pm

You know how some modern herbivores show a preference for certain plants and avoid others, thus following specific plant growth patterns across areas? Well the triassic period may have been exactly the same or it might not, there simply isn’t enough information in the fossil record to know for sure! sarc

John Tillman
Reply to  Ed Zuiderwijk
June 13, 2022 5:59 pm

What happens when climate changes from warmer and drier to cooler and wetter is that species adapted to moister conditions expand their range. Some others may go extinct, or be extirpated locally.

Too few dinosaur species are known from this formation to say to what effect the climate change affected them.

It’s not even clear that Herrerasaurus (and two other members of its family found in the formation) is a dinosaur, although it’s close. Their acetabula are still slightly closed. a dino, but to what group it belongs remains controversial. It’s now generally thought to be a basal sauropodomorph, but probably omnivorous. A third group, more confidently classified as sauropodomorphs, has two genera. There’s also Eodromeus, ranked as a basal theropod.

No obvious ornithischians have been found, although members of this suborder have been found in Late Triassic South Africa, then connected to Argentina on supercontinent Pangaea.

Last edited 11 months ago by Milo
June 13, 2022 2:13 pm

Real Science! I was beginning to think it had gone extinct.

Reply to  Rah
June 13, 2022 2:28 pm

It’s amazing, they can define climate(30 years of data) from millions of years ago! This is what we call climate(30 years of data) today.

Ron Long
June 13, 2022 2:45 pm

Happy to see that CONICET has produced an actual scientific study. While walking through terrestrial equivalent formations in the Neuquen Basin, a little more south in Argentina, I saw the same general change in recorded paleo-climate. The sudden appearance of large cluster of fossilized tree trunks, containing a wide variety of fossilized dinosaur bones (a river flood record, where trees and dinosaurs were caught up and deposited in tangles), begins in the mid-Jurassic and continues to the end of the cretaceous.

June 13, 2022 2:48 pm
Reply to  ResourceGuy
June 13, 2022 3:42 pm

Zombie company.

Reply to  ResourceGuy
June 14, 2022 1:01 pm

I was sure GM would be in financial trouble again sooner or later after the great bail out on the backs of the tax payers during the last recession.

During WW II GM ending up producing 30% of the arms and materials produced in the US used to fight the war. When it was found that a Liberty ship could haul 100 assembled trucks but if not assembled could haul the parts for about 1,000 trucks, it was GM that initially set up and ran the overseas facilities to assemble the trucks. The largest in Iran where the assembled trucks were filled with lend lease and Russian drivers took them into Russia.

When I was a kid, my town of Anderson, IN had 18 different GM plants and Delco and Guide lamp HQ were here. About 1/2 my graduating class from HS went to work for GM. Now? Not a single GM plant remains here.

Mike Lowe
June 13, 2022 2:57 pm

By coincidence, I am currently reading a kindle book about the Argentinian “dinosaur” fossils. This is all news to me, including tales of the hardships endured by the fossil-hunters back in the 19th century. The hardships they endured, with few modern facilities and almost no public recognition, required enormous determination. On occasion they travelled some way up blind alleys before having to retrace their steps and revise their opinions of past events. Although I know virtually nothing of this subject, I have long suspected that the conditions under which some creatures died would have varied greatly, and fossilisation would not necessarily have occurred at the same rate as would have applied to their living populations. Then, of course, there is the random aspect of searches for fossils, which may have affected the rate at which they were discovered. Random discovery of examples may well have affected the presumptions made by subsequent experts.

John Tillman
Reply to  Mike Lowe
June 13, 2022 6:55 pm

You think Argie paleontologists had it hard!

In the US West during the 1870s Bone Wars, competing museum teams tried to blow each other up with the then new-fangled dynamite.

Last edited 11 months ago by Milo
Reply to  Mike Lowe
June 13, 2022 11:24 pm

Whoops, you let the paleontology secret out – they are just making guesstimates! Very limited amount of fossils in any given age and they go and generalize like they had cameras rolling back then.

Reply to  PCman999
June 14, 2022 1:02 pm

“There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.”

Mark Twain.

Peta of Newark
June 13, 2022 11:44 pm

Quote:These fossil-rich sedimentary rocks were deposited by rivers and streams between ~231 and 226 million years ago during the Late Triassic Period in what is now northwestern Argentina (La Rioja and San Juan provinces). In the middle of the formation, the researchers observed a clear change in conditions approximately from warmer, drier conditions to more temperate humid conditions

Just guessing:
There was a fairly major earthquake/landslip and it changed the course(s) of the river(s) in the area they’re looking at

Andy H
June 14, 2022 12:16 am

The most successful animals and plants are those that could cope with a wide variety of conditions (and don’t die if there is a cold winter or hot summer). They have the widest ranges and don’t suffer population crashes when conditions change. The most successful animal (us) is most successful because it is smart and can adapt. That is why we are everywhere and climate change is not going to wipe us out.

June 14, 2022 5:40 am

Sampling biases are a natural plague of all scientific investigation. Scientists can only discover what is still available, not that which existed but is no longer available to be found ..and scientists cannot find that which cannot be sensed by their current technology. That is why science is a process, not an outcome. The statement that “the science is settled” is a moronic oxymoron – science and settled are opposite terms. Science by definition can never be “settled”. There is always more to be discovered, analyzed, and understood.

Reply to  Duane
June 14, 2022 10:16 am

“Settled Science” is the claim of the incompetent or fraudulent since time immemorial.

Reply to  Slowroll
June 14, 2022 7:19 pm

Those who state the obvious scientific fact that the earth being round is indeed “settled science” are, according to Slowroll, “incompetent or fraudulent” for making such statements.

And so-called “skeptical” folks like Slowroll still wonder why they cannot taken seriously …

John Tillman
Reply to  MGC
June 15, 2022 5:53 pm

Earth is an oblate spheroid, with bulges. We’re constantly finding out more about its shape.

Early clues came from pendulum clocks which kept good time in the Netherlands, but not in the British American South, where gravity was quite different.

Reply to  John Tillman
June 15, 2022 7:38 pm

In case you weren’t aware, Tillman, an oblate spheroid is also “round”.

Typical “skeptical” objection that only further reveals ignorance.

John Tillman
Reply to  MGC
June 17, 2022 4:46 pm

A plate is round. A frisbee is round. They are not spheres, let alone spheroids.

Typical CACA spewer inexactitude.

A Flat Earther could claim that Earth is round. But then CACA devotees are akin to Flat Earthers in their objections to the scientific method.

Last edited 11 months ago by Milo
John Tillman
Reply to  John Tillman
June 17, 2022 5:14 pm

The Church had largely accepted that Earth is spherical by AD 500. Augustine argued in On the Literal Interpretation of Genesis, that the propoagation of the faith among educated pagans was more important than insisting on the scriptural flat earth.

A millenium later, the issue was whether the earth is still at the center of the universe, or goes around the sun. Another question was whether its orbit is a perfect circle or elliptical.

Science is never settled. Both earth and sun orbit the barycenter of the solar system, while also orbiting the barycenter of our galaxy.

Last edited 11 months ago by Milo
John Tillman
Reply to  John Tillman
June 17, 2022 5:31 pm

To quote the late, great Dr. Michael Crichton, “If it’s settled, it’s not science. If it’s science, it’s not settled.”

Reply to  John Tillman
June 17, 2022 10:41 pm

Such a tragic grasping at straws in order to try (but fail) to be “right”.

Despite these tiresome, ankle biting “objections” from Tillman, the bottom line here remains unchanged: there are many things that are considered to be “settled science”. Those who accept that such things are indeed “settled” are not “incompetent or fraudulent”, as far too many so-called “skeptics” would like to pretend.

To imagine that many obvious scientific facts are “not” for all intents and purposes “settled” is just flat out ridiculous.

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