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Fossil Friday: Did Giant Dinosaurs Swim Across Oceans?

May 24, 2024, 6:27 AM
Photo credit: MCDinosaurhunter, CC BY-SA 3.0 , via Wikimedia Commons.

While mainstream scientists generally claim that Darwinian evolution is unambiguously supported by multiple lines of evidences including biogeography, in reality all these fields are plagued by highly implausible implications of evolutionary hypotheses, again including biogeography. In two previous articles (Bechly 2018, 2023) I discussed the unlikelihood of trans-oceanic dispersal for terrestrial animals, which is implied by certain evolutionary hypotheses, for example about the origin of New World monkeys. This Fossil Friday we will add another absurd case, which made headlines after the highly unexpected discovery of duckbill dinosaurs in Africa (Longrich et al. 2021, 2024). Therefore, today’s featured fossil is the duckbill dinosaur Edmontosaurus from the Late Cretaceous of North America.

Duckbill dinosaurs (Hadrosauridae) originated during the Late Cretaceous in North America and later spread via a land bridge to Eurasia. Due to the breakup of the supercontinent Pangaea in the Mesozoic and high sea levels, Africa was for 75 million years (including the Late Cretaceous) an isolated island continent similar to modern Australia (Gheerbrant & Rage 2006). The vast ancient Tethys ocean separated Africa from Eurasia and America. Consequently, duckbill dinosaurs were not expected to be found in Africa.

A Big Surprise

Therefore, it was a big surprise when Longrich et al. (2021) described the first duckbill dinosaur from the Late Cretaceous of Morocco in North Africa. The new species belonged to a clade of lambeosaurine hadrosaurids otherwise only known from Europe, which arguably implies that these animals had to somehow cross the Tethys ocean to reach the shores of Africa. Longrich et al. discussed the various possibilities for trans-oceanic dispersal by rafting and swimming, and even mentioned that “dispersal across marine barriers also occurs in other hadrosaurid lineages and titanosaurian sauropods, suggesting oceanic dispersal played a key role.” Really? Just imagine a giant sauropod swimming or rafting in the middle of the wild ocean, not to speak about sharks and the large diversity of voracious large marine reptile predators (e.g., mosasaurs and pliosaurs) in the Late Cretaceous that would have happily feasted on such a helpless meat ball. Even mainstream paleontologists considered such “long-distance trans-oceanic dispersal of such large-bodied and highly terrestrial animals” as highly unlikely and implausible (Poropat et al. 2016: 8).

A new study by Longrich et al. (2024) has even documented four different taxa of duckbill dinosaurs inhabiting North Africa in the Late Cretaceous. Paleontologist Nicholas Longrich, the lead author of the two studies is quoted in the press release (University of Bath 2024, also see Butler 2024) as saying:

It’s extremely improbable that dinosaurs could cross water to get to Africa, but improbable isn’t the same as impossible. And given enough time, improbable things become probable. Buy a lottery ticket every day, and if you wait long enough, you’ll win. These ocean crossings might be once-in-a-million-year events but the Cretaceous lasted nearly 100 million years. A lot of strange things will happen in that time – including dinosaurs crossing seas.”

Evolutionary Biology’s Hero

In my article Bechly (2023) I mentioned that since Darwin’s musings, deep time is generally considered as the hero of the day in evolutionary biology to overcome obstacles of low probabilities. I quoted Nobel laureate George Wald (1954), who famously said about the origin of life that …:

Given so much time, the [nearly] “impossible” becomes possible, the “possible” becomes probable, and the “probable” becomes virtually “certain.”

We find such claims all too often, but of course this is nothing but an invalid ad hoc rescue device, unless you can really demonstrate in detail that the available time inflates the probabilistic resources sufficiently high compared to the statistical improbability of an event. Nobody has ever shown this for any case of postulated trans-oceanic dispersal. It is simply assumed that it must have been possible, because it is often the only available explanation within the Darwinian paradigm.

In my first article on this subject (Bechly 2018) I mentioned that in thousands of years of human seafaring there is not a single reported case of a sighting of a vegetation raft with living terrestrial animals as passengers spotted in the middle of the ocean. The only documented cases of modern oceanic dispersal concern a few tiny Anolis lizards (Censky et al. 1998) and a single Aldabra giant tortoise (Gerlach et al. 2006) that floated a few hundred miles between closely neighbouring shores. But this tortoise was very different from a dinosaur, because it can float like a bottle cork by itself without active swimming, and it is adapted to arid habitats, so that it can endure for a longer time without drinking water.

Perhaps a Baby Dinosaur?

One might claim in the case of dinosaurs that it might have been a baby dinosaur on a large vegetation mat, but a single baby dinosaur could not found a new population. So, either you have to postulate a complete flock of floating baby dinosaurs, or an adult pregnant female dinosaur. Baby dinosaurs are much more vulnerable and would hardly survive an ocean crossing without fresh water, and an adult dinosaur of several meters length would certainly not have been supported by any reasonable vegetation raft. Also active trans-oceanic swimming seriously suggested by Longrich et al. (2021) is a desperate and absurd proposal, which cannot be justified (contra Longrich et al. 2021) with comparisons to cases of polar bears or salt water crocodiles swimming long distances, because those animals are well adapted for ocean swimming unlike duckbill dinosaurs. Therefore, dinosaurs rafting or swimming hundreds of miles across the open ocean is not just improbable but rather impossible, and the impossible will not happen even in millions of years.

Nevertheless, there indeed seems to exist good evidence for a dispersal of terrestrial vertebrates between Laurasia and Africa in the Late Cretaceous. The easiest solution for the evolutionists could be that these land masses were no as strictly separated as often claimed, but connected by island archipelagos that allowed for island hopping as dispersal routes as suggested by some authors (e.g., Le Loeuff 1991, Gheerbrant & Rage 2006, Ezcurra & Agnolín 2012, Csiki-Sava et al. 2015), also concerning the distribution of sauropod dinosaurs (Sallam et al. 2018, Vila et al. 2022).

Uncertain Reconstructions

This would at least avoid the ridiculous trans-oceanic dispersal hypothesis, but of course it also reveals the great uncertainty of all our reconstructions of the distant past. It is a lot of guesswork and no firm ground of established knowledge, contrary to all the bold claims to the contrary. Things are virtually made up on the fly whenever needed. If hypothetical island chains can be reasonably postulated to avoid “seafaring” animals, great! If paleobiogeography does not allow this, then it must have been trans-oceanic dispersal by rafting or even swimming anyway. Who cares about probability or empirical evidence, when a simple just-so-story can do the job!

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