Dinosaurs 'already in decline' before asteroid apocalypse

April 18, 2016, University of Bristol

Dinosaurs were already in an evolutionary decline tens of millions of years before the meteorite impact that finally finished them off, new research has found.

The findings provide a revolution in the understanding of dinosaur evolution. Palaeontologists previously thought that dinosaurs were flourishing right up until they were wiped out by a massive 66 million years ago. By using a sophisticated statistical analysis in conjunction with information from the fossil record, researchers at the Universities of Reading, UK and Bristol, UK showed that dinosaur were going extinct at a faster pace than new ones were emerging from 50 million years before the meteorite hit.

he analyses demonstrate that while the decline in species numbers over time was effectively ubiquitous among all dinosaur groups, their patterns of species loss were different. For instance, the long-necked giant sauropod dinosaurs were in the fastest decline, whereas theropods, the group of dinosaurs that include the iconic Tyrannosaurus rex, were in a more gradual decline.

Dr Manabu Sakamoto, University of Reading, the palaeontologist who led the research, said: "We were not expecting this result. While the asteroid impact is still the prime candidate for the dinosaurs' final disappearance, it is clear that they were already past their prime in an evolutionary sense."

'Losing their edge'

"Our work is ground-breaking in that, once again, it will change our understanding of the fate of these mighty creatures. While a sudden apocalypse may have been the final nail in the coffin, something else had already been preventing dinosaurs from evolving new species as fast as old species were dying out.

"This suggests that for tens of millions of years before their ultimate demise, dinosaurs were beginning to lose their edge as the dominant species on Earth."

Professor Mike Benton of the University of Bristol, one of the co-authors of the research, said: "All the evidence shows that the dinosaurs, which had already been around, dominating terrestrial ecosystems for 150 million years, somehow lost the ability to speciate fast enough. This was likely to have contributed to their inability to recover from the environmental crisis caused by the impact."

It is thought that a giant asteroid's impact with Earth 66 million years ago threw up millions of tonnes of dust, blacking out the sun, causing short-term global cooling and widespread loss of vegetation. This ecological disaster meant that large animals reliant on the abundance of plants died out, along with the predators that fed on them.

The new research suggests that other factors, such as the break-up of continental land masses, sustained volcanic activity and other ecological factors, may possibly have influenced the gradual decline of dinosaurs.

'Room for mammals'

This observed decline in dinosaurs would have had implications for other groups of species. Dr Chris Venditti, an evolutionary biologist from the University of Reading and co-author of paper said: "The decline of the dinosaurs would have left plenty of room for mammals, the group of species which humans are a member of, to flourish before the impact, priming them to replace as the dominant animals on earth."

Dr Sakamoto points out that the study might provide insight into future biodiversity loss. He said: "Our study strongly indicates that if a group of animals is experiencing a fast pace of extinction more so than they can replace, then they are prone to annihilation once a major catastrophe occurs. This has huge implications for our current and future biodiversity, given the unprecedented speed at which species are going extinct owing to the ongoing human-caused climate change."

The new study is published in the journal Proceedings of the National Academy of Sciences.

Explore further: Dinosaurs wiped out rapidly in Europe 66 million years ago

More information: Dinosaurs in decline tens of millions of years before their final extinction, Proceedings of the National Academy of Sciences, www.pnas.org/cgi/doi/10.1073/pnas.1521478113

Related Stories

Recommended for you

Researchers engineer a tougher fiber

February 22, 2019

North Carolina State University researchers have developed a fiber that combines the elasticity of rubber with the strength of a metal, resulting in a tougher material that could be incorporated into soft robotics, packaging ...

A quantum magnet with a topological twist

February 22, 2019

Taking their name from an intricate Japanese basket pattern, kagome magnets are thought to have electronic properties that could be valuable for future quantum devices and applications. Theories predict that some electrons ...

Solving the jet/cocoon riddle of a gravitational wave event

February 22, 2019

An international research team including astronomers from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has combined radio telescopes from five continents to prove the existence of a narrow stream of material, ...

33 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

MaxwellSmith
1.2 / 5 (6) Apr 18, 2016
I've always wondered why no dinosaurs survived. Even with less to eat in a global winter scenario caused by an impact, only a few would have needed to make it to repopulate as plant life recovered.

Perhaps destruction of plant life led to a brief period of reduced atmospheric oxygenation that was the real killer of all large animals. A quick, massive, death that contributed to a faster recovery of plant life. Too bad they didn't live to see it. Maybe that's how we'll go, just a quick global suffocation if oxygen does a quick dip for some reason.
rgw
2.3 / 5 (4) Apr 18, 2016
Good news for Homo Sapiens! I love to think that we can last a few million years. My children will own the galaxy!!!!
Bulbuzor
4 / 5 (4) Apr 18, 2016
Good news for Homo Sapiens! I love to think that we can last a few million years. My children will own the galaxy!!!!


While I would love that humanity turns into a sci-fi utopia (and believe it can if we don't anthropocide ourselves), what is the link between this article and your comment?
HannesAlfven
1.3 / 5 (15) Apr 18, 2016
Re: "For instance, the long-necked giant sauropod dinosaurs were in the fastest decline, whereas theropods, the group of dinosaurs that include the iconic Tyrannosaurus rex, were in a more gradual decline."

The sauropods were problematic not only for their necks, but also their total weight. This analysis will lend an extra argument to those who question whether or not gravity must have somehow changed. The Square-Cube law provides a very simple back-of-the-envelope calculation that shows that the Sauropods would not be able to cope with our gravity today. The upper limit with this calculation ends up at around 20,000 lbs, which explains why elephants top out at around 16,000.

There have been many attempts to dismiss this problem rather than have a real discussion about it. God forbid that somebody might actually think for themselves about an anomalous observation.
Bulbuzor
5 / 5 (14) Apr 18, 2016
@HannesAlfven

You find it easier to claim that Earth's gravity increased (and by a lot it seems that you think), rather then a biological adaptation?

Here is an example, found in 45 seconds, of a morphological attribute of sauropods :
"Morphological evidence presented here suggests a semi-tubular manus was an exaptation that ultimately functioned as a weight-distributing structure, and that this unique morphology may have been present in basal sauropods."
DOI: 10.1671/A1108

Can't seem to find any paper in the literature about the Earth's gravity changing so drastically, perhaps you have the key to this mystery?
TehDog
5 / 5 (8) Apr 18, 2016
" The Square-Cube law..."
Knew I'd seen this somewhere. This was not the source, but as pseudo-science goes, it's not bad;
http://www.dinosa...ing.html

"The Square-Cube Law applies to the bone supporting frame of vertebrates in the same way that it applies to non-living objects. If an individual is twice as tall as similar animals, its cross sectional areas of its leg bones are four times greater while its weight is eight times greater. This means that the stress on its bones is twice as much. and so the larger animal is much more likely of breaking its bones. Because of scaling properties, the larger terrestrial vertebrates are at a much higher risk of breaking their bones than the smaller vertebrates."

I Laughed.
obama_socks
1.6 / 5 (7) Apr 19, 2016
" The Square-Cube law..."
Knew I'd seen this somewhere. This was not the source, but as pseudo-science goes, it's not bad;
http://www.dinosa...ing.html

"The Square-Cube Law applies to the bone supporting frame of vertebrates in the same way that it applies to non-living objects. If an individual is twice as tall as similar animals, its cross sectional areas of its leg bones are four times greater while its weight is eight times greater. This means that the stress on its bones is twice as much. and so the larger animal is much more likely of breaking its bones. Because of scaling properties, the larger terrestrial vertebrates are at a much higher risk of breaking their bones than the smaller vertebrates."

I Laughed.
- TehDog
Why?
The tallest man in human history was 8'11.1" and weighed 439 lbs at the time of his death from an infection at the age of 22. In adulthood, he required leg braces to walk and had little feeling in his legs and feet.
antigoresockpuppet
Apr 19, 2016
This comment has been removed by a moderator.
antigoresockpuppet
1.4 / 5 (5) Apr 19, 2016
Good news for Homo Sapiens! I love to think that we can last a few million years. My children will own the galaxy!!!!


No they won't. They'll only foul the earth.
obama_socks
1 / 5 (8) Apr 19, 2016
Captain Stumpy
4.6 / 5 (9) Apr 19, 2016
https://galileosp
a blog referencing himself and some books? and a NAT GEO article that says, and i quote
What could account for such superlative size? Baseball player Jose Canseco offered his own hypothesis on Twitter...
as evidence for less gravity? epic fail
http://www.univer
a better link, but it doesn't support the conclusions of earth having less gravity in the past, unless you're talking about the part that says
the force of gravity on Earth actually changes depending on where you're standing on it...Gravity also decreases with altitude
another epic fail
www.geocities
worst blog yet... not a shred of evidence, just speculative opinion wrapped in bad grammar...

surely you don't think this is evidence that gravity was so much weaker in the Dino age?
we're talking a short time period geologically speaking... so consider that as well

epic fail
EnricM
5 / 5 (9) Apr 19, 2016
This analysis will lend an extra argument to those who question whether or not gravity must have somehow changed. n.


Aliens, no doubt. Or HAARP... or wait, maybe it was Bigfoot.
Whydening Gyre
5 / 5 (4) Apr 19, 2016
[q http://www.univer
a better link, but it doesn't support the conclusions of earth having less gravity in the past, unless you're talking about the part that says;
... the force of gravity on Earth actually changes depending on where you're standing on it...Gravity also decreases with altitude.
surely you don't think this is evidence that gravity was so much weaker in the Dino age?
we're talking a short time period geologically speaking... so consider that as well
Well, Cap'n.. Might not have had to have been that much weaker. Maybe just a little bit, is all it takes...
Additionally, we are a gravity vacuum cleaner, picking up cosmic dust as we travel through the cosmos.
http://www.universetoday.com/94392/getting-a-handle-on-how-much-cosmic-dust-hits-earth/
Every little bit adds mass. And everything on the planet is constantly adjusting to that increased mass...
Just ponderin'...

torbjorn_b_g_larsson
5 / 5 (8) Apr 19, 2016
@deluxe: Good point in a larger perspective. But here I think their main point is that dinosaur species were going into extinction faster than new one arose, across (nearly) the whole board. That is problematic, availability of niches and niche construction or not.

@rgw: I don't see the relevance. Since mammal species becomes 1-2 Myrs old on average, we are already 10 % of the way to extinction. (More likely we will evolve into a new species, same as how Homo erectus got 2 Myrs old and then spawned the species that later became us.)

Also, the galaxy is too large to allow one species to encompass it. To avoid speciation you need at least 1 crossbreeding/generation on average (independent of population size, a quaint result from population genetics). That would mean that due to the universal speed limit vs feasible technology it would be hard to have one species encompass the whole solar system, at that!
Captain Stumpy
4.5 / 5 (8) Apr 19, 2016
Well, Cap'n.. Might not have had to have been that much weaker. Maybe just a little bit, is all it takes
@Whyde
well... no. first - where did these behemoths exists? was it low lying regions or higher elevations? (It would have to be a fairly substantial amount of mass difference etc)
more to the point: were these massive creatures purely land dwellers or are we talking water/land?
we are a gravity vacuum cleaner
where did the additional mass come from to earth? we're talking a geological millisecond... not a long time geologically speaking... and it would leave considerable evidence
Every little bit adds mass
yes and no... this is something that can also be determined using math and models... it is also something that can be determined by evidence, and we just don't see the kinds of massive accumulations of mass/matter that would adjust our gravity to that degree...

find me evidence and i will consider it a viable argument

Captain Stumpy
4.5 / 5 (8) Apr 19, 2016
@Whyde cont'd
Every little bit adds mass. And everything on the planet is constantly adjusting to that increased mass...
Just ponderin'...
it's good to ponder, that is why i value your input, even when it's "out there"
LOL

there would be a lot of evidence that we can actually track, from the EM field to the oceanic life
what are things that lived during that same period, before and after, that we can also study still today for the sake of comparison?
like say... coral
https://en.wikipe...ki/Coral

we know they existed during the same era as the dino's... who were newcomers, geologically speaking (though nowhere new as we are), so we can see the changes of time in places where they lived and built their homes... what we don't see evidence of is altered gravity, which would definitely show in their size, shape, living conditions and more

so the evidence is still the key... find me some to consider and i'll re-think my opinion

Whydening Gyre
4.2 / 5 (5) Apr 19, 2016
find me evidence and i will consider it a viable argument

Unfortunately evidence is in short supply. I did read an article In Universe Today that stated cosmic dust accumulation is anywhere from 5 to 300 metric tons per day. Multiply that by 65 to 300 billion years. A lot of cosmic dust accumulation...:-)
someone11235813
5 / 5 (2) Apr 19, 2016
The even if they were on the way out, the dinosaurs had a pretty decent 130m year run for such big beasts.
dtxx
4.4 / 5 (9) Apr 19, 2016
Chunks of metal called airplanes can now fly. When did chunks of metal ever fly in the past?? Take that gravity chumps!! Dense aether is becoming more dense, creating buoyancy that is multiplied times the gravity reduction constant. Even retired baseball players know that.

Alfven and zephyzeph will back me up on this one guys! You already lost.
Whydening Gyre
4.3 / 5 (6) Apr 19, 2016
Chunks of metal called airplanes can now fly. When did chunks of metal ever fly in the past?? Take that gravity chumps!! Dense aether is becoming more dense, creating buoyancy that is multiplied times the gravity reduction constant. Even retired baseball players know that.

Alfven and zephyzeph will back me up on this one guys! You already lost.

So... Oxygen and nitrogen are now dense aether?
dtxx
5 / 5 (9) Apr 19, 2016
Chunks of metal called airplanes can now fly. When did chunks of metal ever fly in the past?? Take that gravity chumps!! Dense aether is becoming more dense, creating buoyancy that is multiplied times the gravity reduction constant. Even retired baseball players know that.

Alfven and zephyzeph will back me up on this one guys! You already lost.

So... Oxygen and nitrogen are now dense aether?


No but sarcasm is.
TehDog
5 / 5 (7) Apr 19, 2016
@O_S

I laughed because of feats like this;

https://www.youtu...6nFedV6o

"The tallest man in human history was 8'11.1" "

An outlier. They exist in many species.
https://en.wikipe...re_horse
https://en.wikipe...phant%29

SCL assumes uniform density/structural integrity, fine for modelling bricks, not so good at modelling biological structures.
Captain Stumpy
4.5 / 5 (8) Apr 20, 2016
evidence is in short supply
@Whyde
yeah... i aint found any that is credible at all
Multiply that by 65 to 300 billion years
nope. 66 million years, 100 at the very most.

also note, from your UT article
Thing is, no one really knows for sure and so far there hasn't been any real coordinated efforts to find out

http://www.univer...s-earth/

here is a great read on it that was used to refute creationists - with references
This is why i remain skeptical of the lighter gravity argument, really
http://www.talkor...ust.html

.

.

Alfven and zephyzeph will back me up on this one guys!
@Dtxx
ROTFLMFAO
too funny!
5's for both!
torbjorn_b_g_larsson
4.6 / 5 (9) Apr 20, 2016
"i remain skeptical of the lighter gravity argument,".

I've hard of that idiocy before. But Planck cosmology (as well as isolated tests) tell us the physical laws have been unchanged since well into the cold inflation era, i.e. thermodynamics, QM and GR were the same et cetera. That is, the laws were morally the same before our (supposedly local) universe emerged in the hot big bang! (In practice the low energy sector has not been tracked all the way to the HBB. But what is a 10^-31 second here or there...)

Especially GR has been "universally" successful, and show beyond 'aetheric' LOLS that grabbity always was grabbity.
Whydening Gyre
4 / 5 (4) Apr 20, 2016
"i remain skeptical of the lighter gravity argument,".
...
Especially GR has been "universally" successful, and show beyond 'aetheric' LOLS that grabbity always was grabbity.

TL,
I think the differing thoughts on the matter were not that gravity has changed it's rules, but that the Earth was less dense and had less mass...

Cap'n.
Lack of evidence is why I was generous with the year estimate...:-)
Altho... planets have been accumulating space dust for roughly 4-5b years... it's pretty cleared out by now in comparison... There must have been at least a minor change in gravity well size of Earth in that time.
Captain Stumpy
4.3 / 5 (6) Apr 20, 2016
planets have been accumulating space dust for roughly 4-5b years... it's pretty cleared out by now in comparison... There must have been at least a minor change in gravity well size of Earth in that time
@Whyde
minor since 4.5 billion years ago?
... maybe.
See : http://www.talkor...ust.html

you can do the math and figure out the proportion or overall effect

but as noted above, there is no major change in mass that would account for the claims of the dust accumulation conjecture.

Whydening Gyre
4 / 5 (4) Apr 20, 2016
planets have been accumulating space dust for roughly 4-5b years... it's pretty cleared out by now in comparison... There must have been at least a minor change in gravity well size of Earth in that time
@Whyde
minor since 4.5 billion years ago?
... maybe.
See : http://www.talkor...ust.html

you can do the math and figure out the proportion or overall effect

but as noted above, there is no major change in mass that would account for the claims of the dust accumulation conjecture.

(Shrugging) Like I said before - might not have needed to be much to affect the growth cycles of carbon based life forms...:-)
IE- see how much just a few additional particles of CO2 can affect our climate on a global scale??
Vietvet
4.4 / 5 (7) Apr 20, 2016
@WG

I'd have to find again the the debunking of the "expanding earth" nonsense but
even though it seems there has been plenty of time and material to increase the mass and gravity
of the earth that isn't the case. It is an example of intuition being wrong.
Whydening Gyre
4 / 5 (4) Apr 21, 2016
@WG

I'd have to find again the the debunking of the "expanding earth" nonsense but
even though it seems there has been plenty of time and material to increase the mass and gravity
of the earth that isn't the case. It is an example of intuition being wrong.

all of that in-falling junk has to go SOMEwhere.... If not actually increasing Earth size, then at least adding to density...
Otherwise - where's it going?
Da Schneib
5 / 5 (6) Apr 21, 2016
@Whyde, if you run the numbers you get about 1.192 e-7 %. That's the Earth increasing its mass by one ten-millionth of a percent.

It's like a fly landing on North America.
Whydening Gyre
5 / 5 (2) Apr 21, 2016
@Whyde, if you run the numbers you get about 1.192 e-7 %. That's the Earth increasing its mass by one ten-millionth of a percent.

It's like a fly landing on North America.

Thanks, The Da. That puts it into "easy to get" perspective...
rgw
not rated yet Apr 24, 2016
Good news for Homo Sapiens! I love to think that we can last a few million years. My children will own the galaxy!!!!


While I would love that humanity turns into a sci-fi utopia (and believe it can if we don't anthropocide ourselves), what is the link between this article and your comment?

I have eight successful and happy adult children plus ten (and counting) grandchildren. Two generations times 10,000. You do the math.(;>)
Megapixel
1 / 5 (1) Apr 26, 2016
The Gravity Theory of Mass Extinction explains how surface gravity, not universal gravity, on the Earth has changed. It happens when the Earth's cores move off-center. This happens when a large continental mass, e.g., Pangea, moves to a higher latitude, which it did. Based on the conservation of angular momentum either the Earth's rotational velocity must change or the cores must moved off-center to maintain the angular momentum.

Canseco tried to hijack this theory. There is a YouTube video that summarizes this theory as well as a website.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.