@nataliajagielska.bsky.social has been supporting a great cause with Doodles for Hong Kong, even sketching my favourite Cambrian arthropod, Opabinia regalis.

For the last #FossilFriday of 2025, I’m sharing my favourite group of armoured fishes. Placoderms were an ancient group of fishes that lived during the Silurian and Devonian, between 430 and 360 million years ago. These examples show just how varied their morphology was.

Wishing everyone a Happy Christmas! Behind door 25 of the Fossil Advent Calendar is Lambeosaurus lambei. This example was a juvenile that lived 75 million years ago during the Cretaceous period and was found in Alberta, Canada.

Christmas Eve and day 24 of the Fossil Advent Calendar! Behind today’s door is Bothriolepis canadensis, a placoderm that lived 375 million years ago during the Devonian Period. This example was found in Quebec, Canada. Come back tomorrow for one last door!

Day 23 of the Fossil Advent Calendar is also #TrilobiteTuesday! Thysanopeltis speciosa was a trilobite that lived 389 million years ago during the Devonian period. This example was found in Morocco!

Door 22 of the Fossil Advent Calendar reveals Haplophrentis carinatus, an invertebrate that lived 506 million years ago during the Cambrian period. It lived on the sea floor and had a long, conical shell. This example was found in British Columbia, Canada.

A fish from the Age of Fishes for day 21 of the Fossil Advent Calendar! Eusthenopteron foordi was a lobe-finned fish that lived 375 million years ago during the Devonian period. This example was found in Quebec, Canada.

A slab of trilobites hides behind door 20 of the Fossil Advent Calendar! Pseudogygites latimarginatus lived 450 million years ago during the Ordovician period. This group was found in Ontario, Canada.

A trilobite for this #FossilFriday! Pseudogygites latimarginatus lived around 486 million years ago during the Ordovician Period. This example was found in Ontario, Canada.

It's #FossilFriday and Day 19 of our Fossil Advent Calendar! Today we have Eramoscorpius brucensis, an extinct species of scorpion that lived 432 million years ago during the Silurian Period. This example was found in Ontario, Canada.

A Carboniferous monster hides behind door 18 of the Fossil Advent Calendar! Tullimonstrum gregarium, better known as the Tully Monster, was a soft-bodied marine creature that lived around 310 million years ago. This example was found in Illinois, USA.

Door 17 of the Fossil Advent Calendar reveals Yawunik kootenayi, an arthropod that lived 506 million years ago during the Cambrian period. This example was found in Kootenay National Park, British Columbia, Canada.

Another trilobite hides behind Door 16 of the Fossil Advent Calendar for #TrilobiteTuesday! Olenellus clarki lived around 512 million years ago during the Cambrian period, with this example found in California, USA.

One of my all-time favourite Cambrian fossils is hiding behind Door 15 of the Fossil Advent Calendar: Opabinia regalis. This remarkable creature lived around 506 million years ago, with this example having been found in British Columbia, Canada!

The Fossil Advent Calendar gives us Amiskwia sagittiformis for Day 14! This organism lived around 506 million years ago in the seas of the Cambrian period, with this example found in British Columbia, Canada.

Door 13 of the Fossil Advent Calendar reveals Canis lupus, better known as the Grey Wolf. Grey wolves have been around for hundreds of thousands of years, with this example dating to around 21,500 years ago.

A giant of the Silurian seas for this #FossilFriday! Acutiramus macrophthalmus was a eurypterid that lived 421 million years ago. This example is made up of several specimens found at one site in New York, USA. These Paleozoic predators could reach 2 metres in length!

Palaeozoic arthropods are among my favourite fossils to observe, and this #FossilFriday, door 12 of the Fossil Advent Calendar does not disappoint! Eurypterus remipes lived 421 million years ago during the Silurian Period. This example was found in Ontario, Canada.

Behind door 11 of the Fossil Advent Calendar is an Ichthyosaur, Hudsonelpidia brevirostris! This is the holotype specimen which was found in British Columbia, Canada. It lived 210 million years ago during the Triassic period.

We're interviewing Utah's State Paleontologist JIM KIRKLAND (@paleojim.bsky.social) on today's #Twitch stream! He'll be telling us all about his newly published paper on Jurassic armored dinosaurs — and you can tune in and ask him questions LIVE @ twitch.tv/paleontologizing

What’s lurking behind door 10 of the Fossil Advent Calendar? Nectocaris pteryx! This animal lived in the seas of the Cambrian Period around 506 million years ago. This example was found in Yoho National Park, British Columbia, Canada.

Another #TrilobiteTuesday on the Fossil Advent Calendar means another trilobite behind door 9. This is a curious example I spotted at the museum, I have not been able to find much information about it, giving me yet another reason to go back for a visit!

Day 8 of the Fossil Advent Calendar gives us Wiwaxia corrugata. This scaly organism lived 506 million years ago during the Cambrian Period. This example was found in Yoho National Park, British Columbia, Canada.

Fossilised fish are some of my favourite fossils to look at, and luckily for me, door 7 of our Fossil Advent Calendar gives us Mioplosus labracoides. This fish lived 53 million years ago during the Eocene epoch and was found in the Green River Formation of Wyoming, USA.

Behind door 6 of our Fossil Advent Calendar is an extinct species of comb jelly. Ctenorhabdotus capulus lived 506 million years ago during the Cambrian Period. This example was found in Yoho National Park, British Columbia, Canada.

Sharing an ancient sponge for this #FossilFriday! Wapkia elongata lived 506 million years ago during the Cambrian Period, with this example found in Yoho National Park, British Columbia, Canada.🧽

Day 5 of the Fossil Advent Calendar is also #FossilFriday, and what a special one it is! Zuul crurivastator lurks behind today’s door, which is fitting as she’s back on display at my local museum. Zuul was an ankylosaur that lived 76 million years ago and was found in Montana.

Behind door 4 of our Fossil Advent Calendar is a crinoid, Encrinus liliformis. Crinoids first appear in the Ordovician period and still exist today. This extinct species lived 245 million years ago, and this specimen was found in Germany.

We’re galloping into the third day of the Fossil Advent Calendar with Hyracotherium, an early relative of modern horses. It lived 55 million years ago. The cast shown here is from a specimen found in the UK.

Day 2 of the Fossil Advent Calendar also falls on #TrilobiteTuesday, and luckily for us that’s exactly what we have behind Door 2! Psychopyge elegans was a trilobite from the Devonian Period, and this example was found in Morocco.

It’s the first of December and the first day of our Fossil Advent Calendar! Hiding behind Door 1 is Anomalocaris canadensis, an arthropod that lived during the Cambrian Period over 500 million years ago. This specimen was found in Yoho National Park, British Columbia, Canada.

If you're fond of telling your fellow Thanksgiving diners that the turkey is indeed a dinosaur, then I've got an infographic for you From the hips to the wishbone to the wrist joint, a turkey features SCADS of dinosaurian traits visible right there on your Thanksgiving table. Print and share!

A beautifully fossilised sea scorpion for this #FossilFriday! Eurypterus remipes was a species of eurypterid that lived 421 million years ago during the Silurian Period. This example was found in Ontario, Canada!🇨🇦

A one-tusked mastodon for this #FossilFriday! Mammut americanum roamed North America 12,000 years ago. This example was found in Ontario, Canada. Its skull shows evidence that this one lived much of its life with just one tusk, rather than losing it after death.

I'm kicking off 2025 and my third year of posting #FossilFriday with an arthropod from one of my favourite periods to study! Yawunik kootenayi was a species of megacheira that lived 506 million years ago during the Cambrian. It was found in Kootenay National Park, BC, Canada!🇨🇦

For the last #FossilFriday of 2024, I have Kolihapeltis chlupaci! This trilobite was found in Morocco and dates back 389 million years to the Devonian Period.

Wishing everyone a happy Christmas! I can't think of a better way to round out the Fossil Advent Calendar than to reveal Mammut americanum behind our final door! This mastodon lived 12,000 years ago. Notice that this specimen is missing a tusk! #AdventCalendar

Like all good advent calendars, Day 24 is our penultimate (and not last) door on the Fossil Advent Calendar, and it’s also #TrilobiteTuesday! Boedaspis ensifer lived 464 million years ago during the Ordovician Period. This spiny trilobite was found in Russia! #AdventCalendar

Day 23 of the Fossil Advent Calendar reveals a species found only in Texas! Seymouria baylorensis lived 275 million years ago during the Permian Period. Its taxonomic status between amphibian and reptile (or somewhere in between) has been debated! #AdventCalendar

A nearly 3-metre-long fish behind Door #22 of the Fossil Advent Calendar? That’s exactly what we have! Lebachacanthus senckenbergianus was a freshwater shark that lived 295 million years ago during the Permian Period. It was found in Germany! #AdventCalendar

Day 21 of the Fossil Advent Calendar gives us Dendrerpeton acadianum! This amphibian lived 316 million years ago during the Carboniferous Period. This fossil was found in Nova Scotia, which was near the equator during that time. #AdventCalendar

Described in 2010, I have Herpetogaster collinsi for this #FossilFriday, complete with an amazing model to accompany it! This invertebrate lived 506 million years ago during the Cambrian Period and was found in the Burgess Shale, British Columbia, Canada!

Not only is it #FossilFriday, it’s also Day 20 of the Fossil Advent Calendar! Behind Door #20 we have Eramoscorpius brucensis, an aquatic scorpion that lived 432 million years ago. It may have used its leg structure to venture briefly onto land! #AdventCalendar

Door #19 of the Fossil Advent Calendar gives us another dinosaur! Protoceratops andrewsi was a ceratopsian that lived in Asia 80 million years ago during the Cretaceous Period. #AdventCalendar

Behind Door #18 of the Fossil Advent Calendar we have Platecarpus coryphaeus! This marine reptile, a mosasaur, lived around 83 million years ago during the Cretaceous Period. This specimen was found in Kansas, USA! #AdventCalendar

Another #TrilobiteTuesday, another trilobite in the Fossil Advent Calendar! Door #17 gives us Metopolichas platyrhinus, which lived 464 million years ago during the Ordovician Period. This specimen was found in Russia. #AdventCalendar

Two giant pincers greet us behind Door #16 of the Fossil Advent Calendar! Acutiramus macrophthalmus was a eurypterid that could grow to over 2 metres long. It lived 421 million years ago during the Silurian Period and likely used its claws to capture prey! #AdventCalendar

We have a whole marine community behind Door #15 of the Fossil Advent Calendar! This slab, found in Yoho National Park, British Columbia, Canada, dates back 506 million years to the Cambrian Period and shows multiple Trilobites and Waptia fossilised together! #AdventCalendar

Behind Door #14 of the Fossil Advent Calendar we have Sanctacaris uncata! This arthropod lived 506 million years ago during the Cambrian Period. This specimen was found in Yoho National Park, British Columbia, Canada! #AdventCalendar

This week's #FossilFriday example is small... but luckily, there's a big model showing what it might have looked like alive! Habelia optata was an arthropod that lived in the waters 506 million years ago during the Cambrian. This fossil was found in British Columbia, Canada! 🇨🇦