A team of paleontologists led by University of Leeds scientist Dr. Alexander Dunhill has used the so-called ‘Network Theory’ to visually depict the movement of dinosaurs around the world during the Mesozoic era (252 to 66 million years ago) – including a curious exodus from Europe during the Early Cretaceous (146 to 100 million years ago).
A map showing the migration of dinosaurs from Europe during the Early Cretaceous. Image credit: Alex Dunhill / University of Leeds.
While Network Theory is commonly used in computer science for quantifying internet data, such as friend connections on Facebook, it has only recently been applied to biology research and this is the first study to use it to on dinosaur research.
“Network Theory has been studied in physics for a number of years, however it is finally permeating into other disciplines,” said team member Dr. James Sciberras, from the University of Bath.
“This idea that most things can, and should, be considered in the context of the whole system will lead to some exciting new findings in a wide range of fields.”
Dr. Dunhill and his team’s research reaffirms previous studies that have found that dinosaurs continued to migrate to all parts of the world after the supercontinent Pangaea split into land masses that are separated by oceans.
“We presume that temporary land bridges formed due to changes in sea levels, temporarily reconnecting the continents,” Dr. Dunhill said.
“Such massive structures – spanning, for example, from Indo-Madagascar to Australia – may be hard to imagine.”
“But over the timescales that we are talking about, which is in the order of tens of millions of years, it is perfectly feasible that plate tectonic activity gave rise to the right conditions for such land bridges to form.”
The paleontologists used the Paleobiology Database that contains every documented and accessible dinosaur fossil from around the world.
Fossil records for the same dinosaur families from different continents were then cross-mapped for different periods of time, revealing connections that show how they have migrated.
Some regions of the world, such as Europe, have extensive fossil records from a long history of palaeontology digs, while other parts of the world have been largely unexplored.
To help account for this disparity in fossil records, which could otherwise skew the findings, the team applied a filter to the database records to only count the first time that a dinosaur family connection occurred between two continents.
The findings, published online today in the Journal of Biogeography, support the idea that, although continental splitting undoubtedly reduced intercontinental migration of dinosaurs, it did not completely inhibit it.
Surprisingly, the study also showed that all connections between Europe and other continents during the Early Cretaceous were out-going.
“This is a curious result that has no concrete explanation,” Dr. Dunhill said.
“It might be a real migratory pattern or it may be an artifact of the incomplete and sporadic nature of the dinosaur fossil record.”
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Alexander M. Dunhill et al. Dinosaur biogeographical structure and Mesozoic continental fragmentation: a network-based approach. Journal of Biogeography, published online April 25, 2016; doi: 10.1111/jbi.12766
