Sarcosuchus ('flesh crocodile')

Sarcosuchus was ridiculous. Growing up to 39 feet long and weighing 8 tonnes, sarcosuchus make modern crocodiles look positively Toys 'R' Us by comparison.  For a fun juxtaposition, here's what a sarcosuchus head would look like stood next to a modern man in an Hawaiian shirt:

Our understanding of this true giant started in 1964, when a nearly complete skull was found in Niger, Africa. To make room for its 132 teeth, the head of the sarcosuchus was 6 foot alone!

Sarcosuchus lived 112 million years ago, in the mid-Cretaceous period of the Mesozoic era, and displayed a lot of the features and characteristics of their crocodilian descendants today. The sarcosuchus could not 'death roll' like modern crocodiles do, but had a bite that was so powerful that it didn't need to perform such acrobatics to prepare its meal. Such was its size that its only potential for competition came from the 49-foot dinosaur Spinosaurus, one of the fiercest and largest predators this planet has ever seen (Spinosaurus has a star turn in Jurassic Park III, if you remember.)

Without knowing who would win in a sarcosuchus vs spinosaurus fight, what can be said with certainty is that both of these creatures were unable to use their awesome statures to survive the changing climate towards the end of the Cretaceous period. As the Earth's climate became drier, neither could adapt from their reliance of an aquatic habitat. Both went extinct roughly 90 million years ago, a good deal of time before the Cretaceous-Paleogene mass extinction came for pretty much every other living thing 25 million years later.

PS: Here's Nigel Marvin re-enacting what a human-sarcosuchus encounter might play out like. I love you, Nigel Marvin.

Megatherium Americanum (Giant Ground Sloth)

In terms of the Earth's  history, the Pleistocene Epoch (beginning 2.6 million - 11,000 years ago) was a particularly exciting period of development and change for mammals. The most recent Ice Age occurred, and within this time homo sapiens evolved to the beautiful beach babes that we are today. But most exciting of all was the rise and fall of the megafauna, giant beasts which roamed Australia and North and South America. Megafauna are classified as large or giant animals, and so elephants today fall under that category. (When they go extinct in about 5 minutes time, perhaps future generations will look at elephants in the same way that we look at megafauna of the Pleistocene epoch.)

 No Pleistocene megafauna has captured my imagination like Megatherium Americanum, the largest of the giant ground sloths that inhabited South America. There has been much debate on whether these beasts were omnivores, but what can be said with certainty is the 13 foot tall giants used their stature and massive claws to shred vegetation off of the plant life around them, much of which was unattainable to their short-arsed herbivore contemporaries. It's incredible to think that, despite weighing 4 tonnes, the megatherium were able to support that frame and walk on their hind legs. Still, I suspect many of us will manage a similar feat after the festive season has ended.

 What made the megatherium and other megafauna go extinct at the end of the Pleistocene epoch is hotly contested. The most popular theory points the finger at homo sapiens (again), as their global movements correlate with a rapid extinction of other species (again). In their excellent book 'Megafauna: Giant Beasts of Pleistocene South America', Farina, Vizcaino and De Juliis, cite evidence of a Lestodon sloth collarbone found in Uruguay with 87 human-made marks - chopping sawing, incisions and scraping. Whether this means that homo sapiens actively sought out and hunted megafauna, or whether the homo sapien nomads enjoyed an opportunistic find, it indicates an exciting period in our history where our ancestors shared a stage with these extinct beasts.

 Other theories come from a changing climate and extraterrestrial debris - that falling objects from space set areas of North America on fire and caused extreme climate disruption. This theory holds a lot of questions about our own sustainability, because it shows the devastating domino effect that occurs when food chains and ecosystems are disturbed.

                               

Anyway, more on Megafauna later - you won't believe the size of the Glyptodon armadillo!

Anthropornis Penguin

Whether it's the online videos of them slipping and sliding all over the Antartic, or just their comical way of waddling around, penguins are one of nature's most popular animals, enjoying the sort of celebrity status that hippos used to have, before everyone realised that hippos are actually extremely aggressive (see also: Bill Cosby)

But whilst modern penguins are certifiably fun for Planet Earth - with an added cute factor that many of them mate for life - there's something a little less Disney about the Anthropornis penguin, a terrifyingly giant penguin that lived during the late Eocene epoch in the Paleogene period 37-45 million years ago. Fossil discoveries - including a 9cm tarsometatarsus (a bone found only in the lower leg of birds) suggest that this bird could have measured anywhere between 5.5 - 6.5 feet tall. By comparison, Emperor penguins are the tallest of the living penguin genus, at 3.5 feet tall.

I would love to be able to press a button and have a couple of hundred Anthropornis penguins come back to life and just waddle around, trying to inconspicuously blend into our crowd scenes. And seeing as they would have matched us at head height, a homo sapien vs anthropornis basketball match would make for interesting viewing.