EGU Blogs

Ecology

Why I think the Jurassic/Cretaceous boundary is super important

This was originally posted here.

Mass extinctions are insanely catastrophic, but important, events that punctuate the history of life on Earth. The Jurassic/Cretaceous boundary, around 145 million years ago, was originally thought of to represent a mass extinction, but has subsequently been ‘down-graded’ to a minor extinction event based on new discoveries.

However, compared to other important stratigraphic boundaries, like the end-Triassic or the end-Cretaceous, both time periods representing mass extinction events, the Jurassic/Cretaceous (J/K) boundary actually remains really poorly understood. This is both in terms of what was going on with different animal groups at the time, and what environmental changes were occurring alongside this.

Well, I have a new research paper out now that synthesises more than 600 research articles, bringing them together to try and build a single picture of what was going on around this time! It’s free to read here, and is essentially the literature review from my thesis, or as I like to think of it, the justification for my existence as a researcher!

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New species of ‘river dolphin’ reveals their ancient marine origins

A new species of extinct dolphin closely related to modern Amazonian ‘river dolphins’, but which dwelled in ancient oceans, is helping to solve the mystery of how and when dolphins adapted for life away from the sea.

Freshwater dolphins are endangered, largely due to human activity. In modern ecosystems, only five or six species remain, and among these, the Yangtze ‘river dolphin’ was declared ‘functionally extinct’ in 2006.

These animals are truly remarkable, and show what scientists have interpreted as adaptations for helping to navigate the murky waters of the winding rivers they inhabit: broad, paddle-shaped flippers, and long narrow snouts – much longer than their modern, sea-dwelling cousins – and flexible necks for catching rapidly darting prey.

An artist's recreation of Isthminia panamensis feeding on a flatfish. Many features of this new species appear similar to today’s ocean dolphins, yet the new fossil species is more closely related to the living Amazon River dolphin. Image: Julia Molnar / Smithsonian Institution

An artist’s recreation of Isthminia panamensis feeding on a flatfish. Many features of this new species appear similar to today’s ocean dolphins, yet the new fossil species is more closely related to the living Amazon River dolphin. Image: Julia Molnar / Smithsonian Institution

Scientists from the Smithsonian discovered a new genus and species of extinct ‘river dolphin’, hailing from the Caribbean Coast of Panama 6 million years ago during a time known as the Miocene. Based on a skull and parts of the right flipper, they estimate it could grow to more than 9 feet in length, just slightly larger than its modern relatives. The new animal is named Isthminia panamensis, as a dedication to the people of the Republic of Panama, and the many scientists who’ve studied the biology and geology of the region.

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They might be giants, but how could they live with each other?

Sauropod dinosaurs are the biggest animals to have ever walked on land. They are instantly recognised by their long, sweeping necks and whiplashed tails, and nearly always portrayed moving in herds, being stalked by hungry predators.

In recent years, a huge amount of taxonomic effort from scientists has vastly increased the number of known species of sauropod. What we now know is that in many areas we had two or more species co-existing alongside each other.

A question that arises from this, is how did we have animals that seem so similar, and with such high energy and dietary requirements, living alongside one another? Was there some sort of spinach-like super plant that gave them all Popeye-like physical boosts, or something more subtle…?

Camarasaurus

Hi there, Camarasaurus! One of the iconic dinosaurs of the Morrison Formation (source)

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How fast was the demise of the dinosaurs?

How fast was the demise of the dinosaurs?

It’s dark. It’s always dark these days. Lights in the sky burn your eyes, so you keep your face to ground in the hopes that they’ll go away. But they don’t. The air is heavy. Heavy with poisons that make it difficult to breathe. Heavy with foreboding dread.

You, my unfortunate friend, are going through a mass extinction!

There have been five periods of mass extinction in the past. These represent major phases in the history of life where we see global reorganisations of ecosystems and their inhabitants.

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