Hank Woolley

The fossilized spinal column of the early mammal relative Thrinaxodon embedded in exposed bedrock that outcrops in the icy landscape of the Central Transantarctic Mountains

It’s Antarctica Day! Give it up for this articulated skeleton of Thrinaxodon, an early mammal relative from 250 million years ago, found in the Transantarctic Mountains 8 years ago. This continent has an amazing fossil heritage that we’re continuing to learn more about!

Global sampling decline erodes science potential of natural history collections - Nature Communications Natural history collections hold over two billion specimens representing Earth’s biodiversity, but their scientific value depends on continued specimen collection and digitisation. This study demonstr...

In an era marked by rapid climate change and biodiversity loss, it is imperative that we continue to invest in the unique value of natural history collections data

"Global sampling decline erodes science potential of natural history collections" 🧪

GenAI has polluted image search results, especially for animal pics. It’s now basically impossible to find accurate art references.

Enter this: a repository of open-access, AI-free images of wild & exotic taxa. Artists creating *without AI* have blanket permission for derivative/transformative use.

New paper alert! (My first!)

This is a benchmark paper on all NPS fossils within the State of Utah through 2024. Loads of illustrations by me and pic by coauthors and collaborators. Open access, free to download! Thanks to all who made this possible!

giw.utahgeology.org/giw/index.ph...

Cover of new paper shows geologic section with fossils of a variety of national parks and monuments in Utah.

New paper alert!! Thanks to @tuttran.bsky.social for putting us all together for his first publication! It will be helpful to have much of this data in one place. Check it out: giw.utahgeology.org/giw/index.ph...
#NPSpaleo

Squamate optic nerves are having a week #2025SVP IYKYK

PhyloWeaver – Interactive phylogenetic tree editor Edit and visualize phylogenetic trees directly in your browser. PhyloWeaver lets you interactively rearrange tree topologies and export high-quality figures for publications and presentations.

I’ve released a tool to sketch and edit phylogenetic trees!
yawak.jp/PhyloWeaver/

Load a Newick file and intuitively add/remove/resize branches.
Useful for quick conceptual trees, extracting subtrees, or turning ideas into Newick.

This is a "reindeer cyclone", a defensive behavior that has been observed in herds of reindeer, even in captivity.

The fawns and older animals are at the center, the strongest animal in the outer lanes.

The point is to confuse the brains of predators accustomed to stalking a single outlier.

The Case of the Tiny Tyrannosaurus Might Have Been Cracked

My latest for @nytimes.com! For 40 years, paleontologists have grappled over whether a small tyrannosaur — named Nanotyrannus — was its own animal, or simply a teenage T.rex. The debate has been ... contentious. Which is why it's so fun to finally be able to say this:

Folks? Nanotyrannus is real.

Skull of a small mosasaur as found, with a 2: chip brush for scale. Hard to see in the chalk but it appears the entire skull is present

Thinking back to the spring with the cutest little Tylosaurus skull I've seen in the past few years. Just look at that stubby little rostrum (no shade, he's trying his best)

Based on strat location in the Niobrara, it's probably a juvenile T. kansasensis. Can't wait to see this one get prepped 🧪

Loss of macroevolutionary species fitness explains the rise and fall of clades - Nature Ecology & Evolution The interplay between speciation and extinction rates shapes clade diversity dynamics. Using a novel phylogenetic model that includes living and fossil lineages, the authors estimate speciation and ex...

Excited to share our new paper where we find that the rise, decline and fall of clades is not explained by the usual suspects (diversity-dependence, ecological opportunities) but rather by species' insidious loss of macroevolutionary fitness: www.nature.com/articles/s41... 1/3

🦎THREAD: We just published something wild in @asn-amnat.bsky.social - lizards missing entire limbs not only survive, but some appear to actually thrive in the wild?!

Let me tell you about the "three-legged pirate" lizards 🏴‍☠️

[Paper: www.journals.uchicago.edu/doi/10.1086/... ]

(1/n)

Out now in Biology Letters, my latest paper tackles an apparently simple question: how many characters are needed to reconstruct a phylogeny? TL;DR: in most cases between 100 and 500, more than a substantial portion of morphological datasets, but the story is more complex... doi.org/10.1098/rsbl...

The importance of palaeontology, Earth history, and science The Society of Vertebrate Paleontology discusses the significance of paleontology, Earth history and science in this insightful opinion piece

Our opinion piece on the importance of science and vertebrate paleontology in the United States was just published by Open Access Government:
www.openaccessgovernment.org/the-importan...
#svp #svppresident

🤣 💛💜💛💜 I stan for purple-yellow heatmaps

Evolutionary rate incongruences in squamates reveal contrasting patterns of evolutionary novelties and innovation Abstract. Understanding the rate of phenotypic evolution can reveal fundamental aspects of organismal evolutionary trajectories. Hence, several studies hav

Our latest paper, now how to conciliate apparently discrepant evolutionary rate patterns in squamates, but which may well apply to any study system with Stephanie Pierce and
@7brumas.bsky.social
#macroevolution

academic.oup.com/sysbio/advan...

🐍🦎 We're all familiar with snakes, but have you heard of legless lizards?

Join Collections Manager Nefti Camacho behind the scenes in the Museum's Herpetology Collection and learn the similarities and differences between the two species!

Utah’s Chinle Formation: Understanding Life in the Triassic [vc_row full_width=stretch_row css=.vc_custom_1617652492747{background-color: #23b7e0 !important;}][vc_column width=1/2][vc_single_image image=5232 img_size=600 x 600 alignment=center css=][/vc_column...

Do you need a good paleo podcast to start your weekend? 🤔

In this interview with Science Moab, NHMU's Randy Irmis, Curator of Paleontology, discusses his research on the Chinle Formation located in southern Utah.

Listen here! ➡️ sciencemoab.org/utahs-chinle...

🙌🙌

Squamate fauna from the Denver Basin shows major ecosystem disruption across K/Pg boundary | Proceedings of the Royal Society B: Biological Sciences The Cretaceous/Palaeogene (K/Pg) boundary marks the most recent and the second-most severe mass extinction in Earth’s history. Marine K/Pg boundary sections that preserve uninterrupted sedimentation are abundant, and thus the global marine response to ...

royalsocietypublishing.org/doi/10.1098/...

nhmlac.org/press/mosasa...

From mosasaurs to snakes and lizards, 'megafilters' shape reptile fossil collections For the more than 242 million years that lizards and snakes appear in the fossil record, they show up mostly as pieces of lizard jaws and snake vertebrae.

Physical traits, habitat, and geological processes are primary factors influencing the completeness of lizard, snake, and mosasaur fossils, shaping our understanding of reptile evolution. doi.org/g94m65

This was an incredibly rewarding project to work on and I hope y’all enjoy reading more about the fossil record of one of the coolest group of animals to walk, climb, glide, slither, and swim the planet! @paleosoc.bsky.social @nhm.org

All these patterns suggest that the squamate fossil record is subject to two taphonomic “megafilters”: 1) anatomy of the animal and 2) affinities to specific environments that preserve/destroy fossil information during deposition. Sampling biases appear to play a secondary role.

We also found some interesting patterns related to “proximal” vs “distal” depositional environments: proximal deposits (alluvial fans, volcaniclastics, aeolian dunes, lakes) tend to preserve more complete squamate fossils than distal deposits (e.g. river deltas)

Quantifying the effects of exceptional fossil preservation on the global availability of phylogenetic data in deep time Fossil deposits with exceptional preservation (“lagerstätten”) provide important details not typically preserved in the fossil record, such that they hold an outsized influence on our understanding of...

The aeolian sandstone results were so anomalous we wrote a whole other paper about it last year: journals.plos.org/plosone/arti...

So in sum, squamate body size and anatomy most likely play a primary role in the information preserved in their fossil records. What are some other factors? Turns out, rocks are a factor too. Specific lithologies preserve more and less complete squamate fossils. Finer-grained material=more complete.

What’s truly fascinating here is the difference between amphisbaenians and snakes: two squamate groups with generally similar body plans, but because amphisbaenian skulls have been fused and modified into basically a shovel with teeth, their record is more complete than snakes (delicate skulls)

Higher completeness for mosasaurs makes sense because they are generally big animals; higher volume of bone and easier to spy on rock outcrop. Bigger lizards (varanoids, monstersaurs) and those whose fossil records are exclusively found in lagerstätten (geckos) also have higher completeness…

So what gives? Well, one factor leading to this pattern might have to do with body plan. Lizards (purple), snakes (orange), mosasaurs (green), and amphisbaenians (aqua) all have fossil records that preserve significantly different distributions of scoreable phylogenetic characters.