EGU Blogs

Cretaceous

Double-whammy signifies the demise of the dinosaurs

March 12, 2014

The meteoric impact that wiped out the non-bird-line dinosaurs is an iconic image of life and death on Earth. It signifies a point in time when life changed forever. It took from us animals that we will never see again.

But was it just a single strike that created these winds of permanent change? The crater from Chicxulub in Mexico is the scapegoat for taking dinosaurs from us, but did it have a partner in crime?

Weighing in at about 180km in diameter, the Chicxulub impact was enormous. Imagine that hitting today – it would be the size of many small countries and islands, and devastate humanity.

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Was the diversity of feeding styles in giant turtles a key to their suckcess?

November 18, 2013

­Sometimes, it can be difficult to figure out how ancient organisms used to eat. Part of the problem is that we can never actually see extinct animals eating (until we invent time-travel.. *taps fingers impatiently at physicists*), and often it can be hard to work out how something ate based just on its anatomy.  Sometimes though, the fossil record chucks up something truly spectacular, and gives us amazing insight into the spectacular diversity of ancient life.

Let’s roll it back a bit.

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What do we know about the origin of flowering plants?

October 15, 2013

bioThis is a guest post by Dan Peppe.  He is an Assistant Professor in the Geology Department at Baylor University.  His research interests are focused on reconstructing ancient climates and ecosystems in North America and East Africa and on developing new and improved palaeoclimate and palaeoecological proxies using methods in paleobotany, sedimentary geology, and paleomagnetism.  More information about Dan and his research can be found on his website: www.danielpeppe.com.  He also tweets about his research and other interests on his Twitter account (@danpeppe). 

Over the last couple of weeks several blogs and news outlet have reported that a new study published in Frontiers in Plant Science (Hochuli and Feist-Burkhardt, 2013) shows that new fossil pollen push back the origin of flowering plants (angiosperms) by 100 million years to the early Triassic (e.g., LiveScience, BBC, ScienceDaily). The headlines and articles lead a reader to assume that there was new evidence showing that angiosperms were present in the Triassic (252-201 million years ago, Ma).  However, the new study actually suggests something quite different that adds to a growing body of evidence pertaining to a larger narrative about the evolution of plants and the evolution of angiosperms.

Fossil charcoalified floras from a Late Cretaceous (Santonian, 86 – 83 Ma) in central Georgia showing amazing 3D preservation and anatomical detail. Images were taken using a scanning electron microscope and are considerably magnified (A magnified X50, B X100, C X20). Flower images are from Figure 4 of Crane et al. (2004).

Fossil charcoalified floras from a Late Cretaceous (Santonian, 86 – 83 Ma) in central Georgia showing amazing 3D preservation and anatomical detail. Images were taken using a scanning electron microscope and are considerably magnified (A magnified X50, B X100, C X20). Flower images are from Figure 4 of Crane et al. (2004).

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Your track or mine?

March 18, 2013

How do you tell between different dinosaurs, when you don’t have any dinosaurs? Trace fossils, like footprints, are ghosts of dinosaurs past, remnants of life entombed within the rocks. Palaeontologists and ichnologists (scientists who study trace fossils, not fish) often used to get confused by the question of matching a dinosaur track to its maker. Dinosaur tracks are known from multiple localities all around the globe, but figuring out exactly which dinosaurs made them, or even what type of dinosaur, has always been a mystery. How do you tell the difference? A classic example of this uncertainty is between the tracks of ornithopod and theropod dinosaurs – both groups walked on two feet (bipedal, mostly – some ornithopods were variably quadrupedal), had the same size ranges, were clawed,  and had three front toes (mostly). This means that often, the trackways looked quite similar, not just in terms of gross morphology, but also in the stride length, which tells us about how fast an animal was moving at the time.

Sometimes, the trackmaker can be a little easier to identify.. Source

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