Researchers have discovered ancient marine predators were far more powerful than any seen today, dominating waters at the very top of an extraordinary food chain.
A team from McGill University, in Montreal, Canada, reconstructed a marine ecological network by analysing all known animal fossils from an area in central Columbia known as the Paja Formation.
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The Paja Formation is an Early Cretaceous sequence that dates to approximately 130 million years ago.
It outcrops around Villa de Layva, near Boyaća in central Columbia, and has preserved incredible numbers of marine fauna – and is particularly famous for its large marine reptiles.
In order to recreate the ancient system, the researchers used fossil body sizes, feeding traits and comparisons with modern species that fulfil similar roles today.
They then compared the Paja model to extant marine ecosystems in the Caribbean, which allowed them to test whether the ancient system behaved realistically enough against the ocean systems we see today.
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Ocean super predators
In today’s oceans, food chains typically reach six levels, with animals such as great white sharks and orcas (what we would call apex predators).
However, in results published in the Zoological Journal of the Linnean Society, researchers discovered that there was a previously unseen seventh level that was filled with enormous marine reptiles.
Some, such as Sachicasaurus and Monquirasaurus, could grow up to and beyond 10 metres long and are known as hyper-apex predators. (The ancient shark Megalodon is also sometimes referred to as a hyper-apex predator.)
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The Paja Formation dates to the Mesozoic era (which comprised the Triassic, Jurassic and Cretaceous Periods), which was shaped by rising sea levels and warmer global temperatures.
It’s believed that these changes fuelled an increase in marine biodiversity (known as the Mesozoic Marine Revolution) that can be traced in the fossil record.
“Understanding this complexity helps us trace how ecosystems evolve over time, shedding light on the structures that support today’s biodiversity,” said Dirley Cortés, lead author and doctoral student at McGill University’s Department of Biology.
While this is an early step in understanding ancient marine ecosystems, scientists will be able to compare more ecosystems as more discoveries emerge – and deepen knowledge of how ancient oceans influenced the modern ones we depend on today.
Read the full paper: Top of the food chains: an ecological network of the marine Paja Formation biota from the Early Cretaceous of Colombia reveals the highest trophic levels ever estimated.
Top image: a Liopleurodon, an extinct genus of carnivorous pliosaurid plesiosaurs.
