Uh-oh. You’ve been spotted by an itty-bitty #FossilFriday.

Psittacosaurus mongoliensis (meaning parrot reptile) lived about 107 million years ago, during the Early Cretaceous. 

Dinosaurs hatched from eggs before growing into adults. This skull, among the smallest dinosaur fossils known, is believed to represent a very young Psittacosaurus hatchling, life-sized models of which can be seen below. Note the relatively large eye socket and the short face. As in mammals and in many other dinosaurs, the skull proportions of Psittacosaurus changed as the hatchlings matured: the relative size of the eyes and brain decreased, and the snout lengthened. 

Find this fossil and the life-sized models in the Museum’s Hall of Ornithischian Dinosaurs

Fossil tree

Let’s face it; tree fossils are pretty darn neat. To fossilize a tree, a full piece of log has to be completely buried in sediment before it is consumed by other organisms or burned by fire. It then has to survive, buried in the sediment without being used by any other organism as an energy source, long enough for fluids and groundwater to wind its way through.

Those fluids and groundwater can lithify the surrounding rocks and replace the organic molecules of the tree structure with silicate minerals, turning it into a rock and in this case preserving the contact between the rock and the sediment.

Thin, fine-grained sediment often takes thousands of years to pile up to depths of several meters as seen here. It can happen faster in the event of a storm, so burial of a tree can happen faster, but still, it’s quite remarkable to see a tree entombed by so many separate layers of dirt. This one was found in Nova Scotia.


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Hey T. rex, you guys are just talking, right? 

When the new fossil hall opens at our National Museum of Natural History in 2019, it will feature this dramatic display of dinosaurs, one that’s never been shown to the public before. @smithsonianmag gives you a peek at the exhibition and the relationship between the T. rex and Triceratops, which appears to be — well, dinner. 

A Dire Wolf For Fossil Friday!

One of the most iconic fossil canines of all time has got to be the dire wolf. Known to science long before the similarly named animal characters in the Game of Thrones, today the best record of dire wolf populations comes from the tar pits of Los Angeles, California. 

This is a dire wolf skull excavated from the La Brea tar pits, one of several tar pit predator specimens in our fossil collection (the majority of Ice Age fossils from the tar pits is curated in California). The dire wolf was about the same size as modern grey wolves, but the former had a more robust skeleton. These top dogs represent the pinnacle of pursuit predators in the evolutionary history of dogs, having leg joints specialized for long-distance running, with a range of motion restricted to a single plane for increased efficiency. They lived in North America at the same time as large hoofed mammals such as camels, horses, bison, and gigantic ground sloths (a skeleton of which is visible in the background), none of which were easy prey. Evidence of the intensity of predation, or perhaps competition with other dire wolves, can be gleaned from healed injuries such the blow to the top of the braincase that this animal survived prior to being laid to rest in its asphaltic grave. 

New research heavily based on the Museum’s fossil dog collection—the largest of its kind in the world—shows how dogs evolved in response to a cooling, drying climate in North America over the last 40 million years. Learn more about this new research. 

Image: AMNH/J.Tseng, posted on Instagram as part of the #TsengTakeover


The Mesozoic Park: Ankylosaurus

Common name: Ankylosaurus (An-kee-loh-saurus) Size: up to 6.25 m (20.5 ft), estimated 4 tonnes (8,800 lbs). Age: Late Cretaceous (68 – 66 million years ago) Geographic range: North America Liked: Armour Disliked: Moving Taxonomy: Animalia > Chordata > Dinosauria > Ornithischia > Ankylosauridae

This big, heavy herbivore is the archetypal armoured dinosaur. It is often compared to a tank.

Its squat frame was covered in large, bony plates (‘osteoderms’), arranged in regular patterns all over its back and tail. The osteoderms along the flanks of some species were spikes, as an extra deterrent. Inside, many of its bones were fused together, providing extra strength at the cost of mobility and grace. Ankylosaurus was a lumberer, not a runner, probably preferring to stand its ground and rely on its armour, rather than trying to escape. Its estimated top speed was just 6 mph.

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Scientists from our National Museum of Natural History recently discovered a new species of ancient sperm whale, and my, what big teeth it has!

The fossil of this toothy whale, named Albicetus oxymycterus (white whale) in honor of  Herman Melville’s Moby Dick, sat untouched in the collection for decades. With the help of 3D scanning, researchers re-examined the fossil and found it belonged to an entirely new group in the sperm whale family.

Read more here. 


An elegant choice for #FossilFriday! These beautiful crinoidea, or sea lilies, were echinoderms like starfish and sea urchins. They were pseudoplanktonic filter feeders, made up of a calcareous stalk at the end of which were flexible arms, which caught algae, unicellular organisms, small crustaceans and the larvae of invertebrates floating in the water.

Fossilized species, such as the Seirocrinus subangularis, formed in abundance in “meadows” on the seabed. Having appeared in the Cambrian period, they were badly affected by the most significant mass extinction that earth has ever seen. Almost 95% of marine species and 70% of terrestrial species disappeared at the end of the Permian period, 250 million years ago.

Crinoids similar to these fossils still cover tropical seabeds today. They were believed to be extinct for a long time – in fact, these modern species were only identified after the discovery of their fossilized ancestors!

These sea lilies - actual size 3 x 2 metres - are on display in our Gallery of Evolution

This ‪#‎FossilFriday‬ is related to our fine feathered friends!

At 7 feet long, Deinonychus belonged to a group of dinosaurs called maniraptors, or “hand-robbers.” Its hands and feet were equipped with sharp claws for catching and grasping prey. The dinosaur’s hollow bones and long legs indicate swift and agile movement.

The Deinonychus exhibit is the only real fossil specimen of its kind on display anywhere in the world. The similarities between Deinonychus and early bird skeletons show that modern-day birds descended from small dinosaurs.

This fossil is located in the Hall of Saurischian Dinosaurs.


Claw marks left on a river bottom in Sichuan, China are evidence for dinosaurs’ ability to swim relatively long distances. According to an international team of scientists in the journal Chinese Science Bulletin, theropod species of dinosaurs were able to travel in relatively deep bodies of water.

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The Crafting of a Mystery

Happy #FossilFriday and World Photo Day! World Photo Day is a global celebration of photography, and marks the anniversary of Louis Daguerre’s invention of the world first practical camera. In observation of the occasion, I thought today would be a perfect day to post a historical paleo photograph. Here, Adam Hermann sculpts a skull for the American Museum of Natural History’s Brontosaurus mount in 1904 (source). At the time, a skull had not been recognized for the animal, but the museum wanted a complete display, so they modeled one based on a camarasaur instead. Little could the artist have known the drama that would unfold over the ensuing century surrounding the validity of Brontosaurus, with particular focus on the skull. Discredited for over 100 years, Brontosaurus has recently returned to validity for new generations to enjoy.

Today, artists just like Adam Hermann continue to sculpt missing pieces of dinosaur skeletons, sometimes by hand, and sometimes sculpting in the computer. Increased understanding allows us to create more and more accurate and convincing guesses about the missing anatomy. Sometimes a complete skeleton is inferred from only a few bones!

Fossil Friday: This Neanderthal’s seen better days…

We recently updated our collection of human evolution skulls. Above we have a very beaten Neanderthal.

Neanderthals represent a fascinating look at the human evolutionary tree. As recently as 30,000 years ago, homo sapiens and Neaderthal’s coexisted. Evidence suggests that we even share close genetic material with other, which is to say at some point we humans and Neanderthal’s interbred.

Neanderthals not only shared physical traits with us, but also seemingly art and maybe even culture. To think that a close relative of ours was making art, as we were also making art is astounding.

More information!
So much science is being done on this right now, shedding new light on our close relatives seemingly daily. Check out the links (all from the last few years) below.

Written by @kironcmukherjee. Last update: January 25th, 2014.

Our FossilFriday star this week is Palaeochiropteryx spiegeli, one of the first bats. This example is 47 million years old and comes from the Messel pit, near Frankfurt, in Germany. The fossils from this site are often incredibly well preserved, in some of the bat specimens even the stomach contents is conserved!

Like modern bats, its wings were formed from enlarged hands, which allowed it to fly amongst the dense Eocene foliage. It was an insectivore, and probably nocturnal like living bat varieties.

This 7cm long fossil is on display in our Gallery of Evolution, where you can find other Messel fossils including the small primitive horse Hallensia matthesi. There are other amazing fossils to be found in the 250 Years of Natural Sciences Hall and in the Dinosaur Gallery.

Watch out for ‪Fossil Friday‬! This “tongue beast” is Glossotherium robustus.
This extinct giant ground sloth belongs to a group of mammals that have bony body armor. You may be familiar with one of these — the armadillo. But where’s the armor in Glossotherium? Don’t look too hard! Its armor took the form of small bones embedded in the skin, which is rarely preserved in fossil specimens. Glossotherium robustus lived 30,000 years ago, in the Pleistocene Epoch.

Find this sloth in the Hall of Primitive Mammals.