University of Tokyo
One researcher at the University of Tokyo is in hot pursuit of dinosaurs, tracking extinct species around ancient Earth. Identifying the movements of extinct species from millions of years ago can provide insights into ancient migration routes, interaction between species, and the movement of continents.
“If we find fossils on different continents from closely related species, then we can guess that at some point there must have been a connection between those continents,” said Tai Kubo, Ph.D., a postdoctoral researcher affiliated with the University Museum at the University of Tokyo.
A map of life – biogeography
Previous studies in biogeography — the geographic distribution of plants and animals — had not considered the evolutionary relationships between ancient species. The new method that Kubo designed, called biogeographical network analysis, converts evolutionary relationships into geographical relationships.
For example, cats and dogs are more closely related to each other than to kangaroos. Therefore, a geographical barrier must have separated the ancestors of kangaroos from the ancestors of cats and dogs well before cats and dogs became separate species.
Most fossils are found in just a few hot-spot locations around the world and many ancient species with backbones (vertebrates) are known from just one fossil of that species. These limitations mean that a species’ fossils cannot reveal the full area of where it was distributed around the world.
“Including evolutionary relationships allows us to make higher resolution maps for where species may have migrated,” said Kubo.
The analysis used details from evolutionary studies, the location of fossil dig sites, and the age of the fossils. Computer simulations calculated the most likely scenarios for the migration of species between continents on the Cretaceous-era Earth, 145 to 66 million years ago.
North and south divide
This new analysis verified what earlier studies suggested: nonavian dinosaurs were divided into a group that lived in the Northern Hemisphere and another that lived in the Southern Hemisphere, and that those two groups could still move back and forth between Europe and Africa during the Early Cretaceous period (145 to 100 million years ago), but became isolated in the Late Cretaceous period (100 to 66 million years ago).
During the Early Cretaceous period, there were three major supercontinents: North America-Europe-Asia, South America-Africa, and Antarctica-India-Australia.
By the Late Cretaceous period, only the North America-Europe-Asia supercontinent remained. The other supercontinents had separated into the continents we know today, although they had not yet drifted to their current locations.
“During the Late Cretaceous period, high sea levels meant that Europe was a series of isolated islands. It makes sense that nonavian dinosaur species differentiated between Africa and Europe during that time,” said Kubo.
Kubo plans to complete additional biogeographical analyses for different time periods to continue tracking extinct species around the world and through time.
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Journal Article
Kubo, T. 27 May 2019. Biogeographical Network Analysis of Cretaceous Terrestrial Tetrapods: A Phylogeny-Based Approach. Systematic Biology, syz024. DOI: 10.1093/sysbio/syz024
Related Links
Tai Kubo’s profile page (Japanese): http://www.um.u-tokyo.ac.jp/people/faculty_kubotai.html
The University Museum: http://www.um.u-tokyo.ac.jp/index_en.html
Good idea.
Does it take into account the possibility that ancient creatures could have migrated aa long way during an individual’s lifetime?
Salmon, albatross and wildebeests would be hard to interpret. And we know nothing of extinct species’ behaviours.
“For example, cats and dogs are more closely related to each other than to kangaroos. Therefore, a geographical barrier must have separated the ancestors of kangaroos from the ancestors of cats and dogs well before cats and dogs became separate species.”
Exactly! And yet our academics have naturalised the Pariah Dog of Asia [the Dingo] in Australia because it arrived three thousand years ago with Asian fishermen and they wonder why our native marsupials can’t cope and are disappearing.
“‘Science’ is the certainty of the ignorance of ‘experts'”.
A dingo ate your baby comes to mind… 🙂
The Dingo probably outcompeted the Thylacine and the Tasmanian Devil which both became extinct on the mainland about at the time it was introduced. It may also have exterminated the Tasmanian Native Hen, which disappeared from the mainland at about the same time. Otherwise it does not seem to have had much effect, probably because it simply replaced the thylacine.
The real catastrophe was the introduction of cats, probably from shipwrecks in the seventeenth century.
“Otherwise it does not seem to have had much effect…”
Compare Tasmania, where the dingo never reached because of SLR, which is the most bio-diverse state in the country, with Fraser Island, where the dingo is worshipped, which has virtually no ground-dwelling natives left left and the dingoes need fishermen to feed them with fish offal.
Plus the occasional child.
There is also a still a good variety of small native mammals in the SW part of WA where native animals contain enough 1080 poison from eating native plants to make them poisonous to cats and foxes. It’s the only part of the mainland I have visited where you see many small native animals. I’ve even seen the numbat there a couple of times.
“The real catastrophe was the introduction of cats”
Absolutely. Plus foxes. But because the dingo is now considered a native our ability to remove cats and foxes is severely restricted.
“For example, cats and dogs are more closely related to each other than to kangaroos. Therefore, a geographical barrier must have separated the ancestors of kangaroos from the ancestors of cats and dogs well before cats and dogs became separate species.”
Exactly! And yet our academics have naturalised the Pariah Dog of Asia [the Dingo] in Australia because it arrived three thousand years ago with Asian fishermen and they wonder why our native marsupials can’t cope and are disappearing.
“‘Science’ is the certainty of the ignorance of ‘experts'”. 2
This is a really interesting piece of science and refreshing to read as a post. It restores faith that there are lots of people doing honest science out there, even if no doubt attempts will be made to misuse honest work to scare people with more climate the Sky is falling porn.
I was also intrigued by a report that scientists are developing the use of a fungus to eradicate malaria carrying mosquitoes. No doubt Greedpeace or the fascist WWF will start a save malaria campaign.
This isn’t new. One of the early pieces of evidence for plate tectonic theory was the distribution of fossils.
Yes. This seemed to a perfect example of the phenomenon of the graduate student discovering something that was widely known before they were born. It has a close relative in the graduate student discovering something that is commonly known in a different discipline.
This is a case of the phenomenon of the graduate student discovering something that was common knowledge before they were born. It has a close relative in the graduate student discovering something that is common knowledge in another discipline. Much like Holly in Red Dwarf, the science community periodically wipes its memory banks so that it can start a fresh round of discovery.
No. It was early evidence for continental drift. Plate tectonics evolved in the mid-1960s as the mechanism that drove continental drift.
People tend to get continental drift and plate tectonics confused, similarly to the confusion between evolution and natural selection. And I’m there to set them straight (in my usual modest and self-effacing way, of course).
There will always be a great deal of uncertainty in phylogenetic analyses based solely on osteological characters. Modern DNA studies has shown that parallelism and convergent evolution is vastly more common than anyone thought previously.
Also that lineages deeply nested in an otherwise homogenous groups can be extremely aberrant, e g the dodo is actually a pigeon and the ground-chough is a tit.
Also one must remember how incomplete the fossil record is, even for large animals like dinosaur. There are intervals of several million years in the Mesozoic, from which not a single dinosaur is known anywhere in the World, and there are vast areas from which not a single dinosaur fossil of any age is known (e. g. Scandinavia, most of Canada, much of Africa, most of Australia and nearly all of Antarctica).
Fossil hunt in Antarctica will have to wait until it melts. Being below 3 km ice makes it difficult. Paleontologists should be applying for grants to excavate for fossils in Antarctica. It is a race to be the first to find one. It should melt any day now if one gives credit.
There actually are a few good Late Cretaceous fossil sites at the north end of the Antarctic Peninsula:
https://www.researchgate.net/publication/255168094_Late_Cretaceous_dinosaurs_from_the_James_Ross_Basin_West_Antarctica
Not a lot anywhere else though.
Commie Bob is right. This news isn’t new or original. I remember reading Edwin Colbert’s book, “Digging Into the Past”, in my local library back in the 1970s. Colbert checked out Lystrosaurus fossils in India and South Africa, and despite Javier’s remarks, didn’t have to wait for ice to melt to discover Lystrosaurus fossils in Antarctica. He said Lystrousaurs was something like a hippo, living along rivers. They certainly couldn’t swim the thousands of miles between India, South Africa, and Antarctica, so obviously the three were connected back in the late Permian and early Triassic.
Nowadays Lystrosaurus is thought to have been fossorial, which would have made it even less likely to cross water barriers.
You got me there, tty, as I had to look up “fossorial”, which is digging or burrowing. A burrowing hippo? Think about having an infestation of burrowing hippos in your lawn!
It doubtful whether it was really aquatic. And Lystrosaurus wasn’t very big, the smallest species was (small) dog-sized and the biggest slightly larger than a pig.
Yes, nothing new. Dinosaur groups have been used to track the breakup of Pangaea for about a century, i.e. decades before the fact (then theory) of “continental drift” was recognized.
Genus Lystrosaurus has also been found in European Russia, Mongolia and China.
Yup. Nothing new. The distribution of dinosaur groups was evidence for the then theory of “continental drift” a century ago, an hypothesis now observed as a fact. African Jurassic fauna was similar to North American, which in the Early Cretaceous resembled European. Late Cretaceous Western North American dinos were related to East Asian, while Gondwanan groups were distinct. Top predators for instance were tyrannosaurs in the NH and abelisaurs in the SH.
Ubiquitous genus Lystrosaurus has also been found in the Moscow Basin, Mongolia and China. It really got around Pangaea, both before and after the Permian extinction.
Sorry about dual post. Thought first one didn’t take because of a call I got while it was being sent.
Fossil and living sloth biogeography was an early clue for Darwin’s insight into the origin of species.
Though Lystrosaurus wasn’t a dinosaur. It was a dicynodont, i. e. a therapsid, and consequently much closer related to mammals (including humans) than to dinosaurs (which are diapsids).
Genus Lystrosaurus died out before the first dinosaur evolved, but many other non-mammalian synapsids did share Earth with Superorder Dinosauria, especially in the Triassic.
I think you’re right. I got the impression reading Robert Bakker’s book, “The Dinosaur Heresies”, that those therapsids were warm blooded, fur covered, egg layers- sort of like the platypus .
Therapsids used to be called “mammal-like reptiles”, but they weren’t reptiles. Synapsids split from reptiles (diapsids) around 312 million years ago, during the Carboniferous Period. Their common ancestors were anapsid amniotes. Anapsids had no holes in their heads behind the eye socket (post orbital fenestrae); synapsids had one and diapsids two.
For about the past 100 million years, the only surviving synapsids have been mammals. Triassic therapsids were indeed very mammalian-looking, but they lacked the key skeletal distinguishing trait of mammals, ie our lower jaw consists of just the dentary bone. The bones at the rear of all other vertebrate mandibles, and which form the joint with the skull, evolved into our middle ear bones. Triassic proto-mammals, like Morganucodon, had both joints.
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