What A 5-Million-Year-Old Bite Reveals About Climate Change And Sharks 👇
This story begins not in the open ocean, but in a dockyard. Decades ago, fossil hunters working along the busy port of Antwerp (a historic Belgian port city which you might know as the world’s diamond capital) uncovered something unusual buried in sediment millions of years old.
Not a diamond, mind you, but what at first glance looked like just another whale skull. But hidden within it was a clue that would take years to fully understand: a shark tooth lodged in the bone.
The single tooth fragment — now studied by researchers including Bournemouth University Professor of Evolutionary Palaeoecology John Stewart and Royal Belgian Institute of Natural Sciences Researcher in Vertebrate Palaeontology Olivier Lambert — offers a window into a very different North Sea that existed roughly 4 to 5 million years ago during the early Pliocene.
Back then, this region was not the relatively low-diversity marine environment we know today. Instead, it was home to a rich community of marine life that included small baleen whales, dolphins, seals and, importantly, large predatory sharks.
While it may seem like a futile effort to study how organisms interacted in the past, scientists can actually begin to understand how ecosystems might respond to the changes happening today by doing just that.
"If you want information about how animals and other organisms might respond to the kind of climate changes our planet is experiencing right now, you need evidence of former responses to such changes,” the Stewart and Lambert say in a Conversation piece they published about their new study featuring this shark tooth.
The fossil record rarely preserves direct evidence of predator-prey interactions. Bite marks on bones are one thing (and quite common), but they often leave room for interpretation, so a tooth fragment embedded in a skull is something else entirely because it directly ties predator and prey together in a single, undeniable moment.
In one case, the skull belonged to a small, now-extinct right whale species called Balaenella brachyrhynus.
Analysis using microCT scanning revealed that the embedded tooth fragment came from a bluntnose sixgill shark (Hexanchus griseus), a deep-water species that still exists today!
The placement of the bite suggests the whale was likely scavenged after death, its body drifting belly-up through ancient seas.
But a second fossil tells a slightly different story; this skull came from a relative of the modern beluga whale, Casatia thermophila. And while here, too, a shark tooth fragment was found embedded in bone, the evidence suggests a more active attack.
The shark, likely an extinct mako species related to today’s great white, appears to have targeted the whale’s head, possibly attempting to access the fat-rich tissues used in echolocation.
More here:
forbes.com/sites/melissacris…