Thomas R. Holtz, Jr.
@arctomet.bsky.social
Tyrannosaur Expert; Dinosaur Paleontologist; University of Maryland Geology Faculty; Director of the College Park Scholars-Science & Global Change Program; Science Author; Cat Dad; 🦖🦕
Pinned
For the new folks, my handle refers to the arctometatarsalian condition of the foot of certain carnivorous dinosaurs (tyrannosaurids, ornithomimids, some troodontids, alvarezsaurids, and oviraptorosaurs). Arctometatarsi involve a compression of the central metatarsal (MT III) between II and IV.
PeerJ<br><br>Resistance of cervical vertebrae in response to muscular stresses in pterosaurs: implications for foraging habits and skeletal pneumatization<br><br>https://peerj.com/articles/20388/<br><br>@peerj.bsky.social
November 25, 2025 at 5:36 PM
PeerJ<br><br>Resistance of cervical vertebrae in response to muscular stresses in pterosaurs: implications for foraging habits and skeletal pneumatization<br><br>https://peerj.com/articles/20388/<br><br>@peerj.bsky.social
Because the world needed ANOTHER species in Mamenchisaurus...
Dai, H., Hu, XF., Tan, C. et al. A new mamenchisaurid sauropod dinosaur from the upper jurassic of Southwest China reveals new evolutionary evidence from East Asian eusauropods. Sci Rep (2025). doi.org/10.1038/s415...
Dai, H., Hu, XF., Tan, C. et al. A new mamenchisaurid sauropod dinosaur from the upper jurassic of Southwest China reveals new evolutionary evidence from East Asian eusauropods. Sci Rep (2025). doi.org/10.1038/s415...
A new mamenchisaurid sauropod dinosaur from the upper jurassic of Southwest China reveals new evolutionary evidence from East Asian eusauropods - Scientific Reports
Scientific Reports - A new mamenchisaurid sauropod dinosaur from the upper jurassic of Southwest China reveals new evolutionary evidence from East Asian eusauropods
doi.org
November 25, 2025 at 5:22 PM
Because the world needed ANOTHER species in Mamenchisaurus...
Dai, H., Hu, XF., Tan, C. et al. A new mamenchisaurid sauropod dinosaur from the upper jurassic of Southwest China reveals new evolutionary evidence from East Asian eusauropods. Sci Rep (2025). doi.org/10.1038/s415...
Dai, H., Hu, XF., Tan, C. et al. A new mamenchisaurid sauropod dinosaur from the upper jurassic of Southwest China reveals new evolutionary evidence from East Asian eusauropods. Sci Rep (2025). doi.org/10.1038/s415...
Reposted by Thomas R. Holtz, Jr.
The occiput of Amargasaurus (Sauropoda, Dicraeosauridae): Reconstruction of the craniocervical muscular insertions with comments on feeding strategy - Militello - Journal of Anatomy - Wiley Online Library onlinelibrary.wiley.com/doi/10.1111/...
The occiput of Amargasaurus (Sauropoda, Dicraeosauridae): Reconstruction of the craniocervical muscular insertions with comments on feeding strategy
Sauropods achieved gigantism partly through neck elongation, but the role of soft tissues remains unclear. We reconstruct the craniocervical muscles of Amargasaurus cazaui (Lower Cretaceous, Argentin....
onlinelibrary.wiley.com
November 25, 2025 at 1:32 PM
The occiput of Amargasaurus (Sauropoda, Dicraeosauridae): Reconstruction of the craniocervical muscular insertions with comments on feeding strategy - Militello - Journal of Anatomy - Wiley Online Library onlinelibrary.wiley.com/doi/10.1111/...
Reposted by Thomas R. Holtz, Jr.
One of my favourite #Pleistocene mammals - and, yes, it has a role in #PrehistoricPlanetIceAge - is the big predatory marsupial #Thylacoleo. Here's an introduction to this fantastic animal.... tetzoo.com/blog/2025/11... #marsupials
Thylacoleo, the Incredible Marsupial Lion — Tetrapod Zoology
Among the most striking and interesting of extinct mammals is the so-called marsupial lion of Australia, or Thylacoleo carnifex …
tetzoo.com
November 24, 2025 at 10:51 PM
One of my favourite #Pleistocene mammals - and, yes, it has a role in #PrehistoricPlanetIceAge - is the big predatory marsupial #Thylacoleo. Here's an introduction to this fantastic animal.... tetzoo.com/blog/2025/11... #marsupials
Reposted by Thomas R. Holtz, Jr.
New seasonal paleontology positions available for Dinosaur National Monument, Petrified Forest National Park and Fossil Butte National Monument. Apply soon, they close after they receive a certain number of apps! #NPSpaleo #PaleoJobs
www.usajobs.gov/job/850816000
www.usajobs.gov/job/850816700
www.usajobs.gov/job/850816000
www.usajobs.gov/job/850816700
USAJOBS connects job seekers with federal jobs across the United States and around the world as the official employment site for the federal government
These positions may be filled for a six month seasonal period, but can vary due to weather conditions, project needs, or funding. Anticipated Entry on Duty: <strong>April 2026</strong>
<p>For more par...
www.usajobs.gov
November 24, 2025 at 6:28 PM
New seasonal paleontology positions available for Dinosaur National Monument, Petrified Forest National Park and Fossil Butte National Monument. Apply soon, they close after they receive a certain number of apps! #NPSpaleo #PaleoJobs
www.usajobs.gov/job/850816000
www.usajobs.gov/job/850816700
www.usajobs.gov/job/850816000
www.usajobs.gov/job/850816700
Reposted by Thomas R. Holtz, Jr.
AP is back in court today to defend itself and the right to speak freely without government retaliation.
Why AP is standing for your right to speak freely
The executive editor of The Associated Press says the news organization is fighting for the right of the press and public to speak freely without being targeted by the government.
bit.ly
November 24, 2025 at 10:30 AM
AP is back in court today to defend itself and the right to speak freely without government retaliation.
Reposted by Thomas R. Holtz, Jr.
Tut Tran has put a huge amount of effort in shepherding this state of the art review of paleontology in Utah's National Parks and Monuments. giw.utahgeology.org/giw/index.ph... Paleontology in these NPS units will always be evolving and new things are already in the works.
A visual paleontological inventory of Utah’s National Park Service areas
| Geology of the Intermountain West
giw.utahgeology.org
November 24, 2025 at 5:35 PM
Tut Tran has put a huge amount of effort in shepherding this state of the art review of paleontology in Utah's National Parks and Monuments. giw.utahgeology.org/giw/index.ph... Paleontology in these NPS units will always be evolving and new things are already in the works.
Reposted by Thomas R. Holtz, Jr.
Bucket list sloth butt selfie!! This beautiful specimen is from Anza Borrego and it has THOUSANDS of in situ osteoderms. There are only two specimens with in situ osteoderms (that I know of) in North America and I’m spending the day with this one.
November 24, 2025 at 6:57 PM
Bucket list sloth butt selfie!! This beautiful specimen is from Anza Borrego and it has THOUSANDS of in situ osteoderms. There are only two specimens with in situ osteoderms (that I know of) in North America and I’m spending the day with this one.
Reposted by Thomas R. Holtz, Jr.
🎓 Looking for an exciting PhD project?
Check out some amazing opportunities on our page! 🌍🔬
👉 palass.org/phd-opportun...
Have a PhD opportunity to share?
You can easily add it using the “Add a PhD Opportunity” button! 📝✨
#phd #phdlife #advertising #palass
Check out some amazing opportunities on our page! 🌍🔬
👉 palass.org/phd-opportun...
Have a PhD opportunity to share?
You can easily add it using the “Add a PhD Opportunity” button! 📝✨
#phd #phdlife #advertising #palass
November 24, 2025 at 7:03 PM
🎓 Looking for an exciting PhD project?
Check out some amazing opportunities on our page! 🌍🔬
👉 palass.org/phd-opportun...
Have a PhD opportunity to share?
You can easily add it using the “Add a PhD Opportunity” button! 📝✨
#phd #phdlife #advertising #palass
Check out some amazing opportunities on our page! 🌍🔬
👉 palass.org/phd-opportun...
Have a PhD opportunity to share?
You can easily add it using the “Add a PhD Opportunity” button! 📝✨
#phd #phdlife #advertising #palass
Reposted by Thomas R. Holtz, Jr.
Epic take-down of Roger Pielke Jr's appallingly shoddy academic "work", which he's used--as an attack dog of the Koch Brothers-funded think tank AEI--to discredit the case for climate action:
In a 2024 paper criticizing the 'billion-dollar-disasters' database, Roger Pielke Jr. published analysis that is best described as a Russian-doll of errors.
Here's my in-depth take down of his appallingly bad work.
economicsfromthetopdown.com/2025/10/26/r...
Here's my in-depth take down of his appallingly bad work.
economicsfromthetopdown.com/2025/10/26/r...
Roger Pielke Jr.’s Appallingly Bad Analysis of Billion Dollar Disasters – Economics from the Top Down
In a recent paper called Scientific integrity and U.S. “Billion Dollar Disasters”, Roger Pielke Jr. published a chart that's so bad I've devoted a whole essay to debunking it.
economicsfromthetopdown.com
November 24, 2025 at 5:41 PM
Epic take-down of Roger Pielke Jr's appallingly shoddy academic "work", which he's used--as an attack dog of the Koch Brothers-funded think tank AEI--to discredit the case for climate action:
Reposted by Thomas R. Holtz, Jr.
It wasn’t a peace plan. It was a surrender plan.
November 24, 2025 at 7:30 PM
It wasn’t a peace plan. It was a surrender plan.
Reposted by Thomas R. Holtz, Jr.
BWAHAHAHAHAHAHAHA!!.... Trump Admin loses ANOTHER one!!
November 24, 2025 at 7:47 PM
BWAHAHAHAHAHAHAHA!!.... Trump Admin loses ANOTHER one!!
Reposted by Thomas R. Holtz, Jr.
This is who she was.
Passionate in her beliefs. Fiercely loyal to her friends. Never afraid to let you know exactly where she stood. The best.
Fun Fact: I remember arguing with her over which of us hated Piggy the most. I was sure I did. She disagreed. It remains unresolved...
Passionate in her beliefs. Fiercely loyal to her friends. Never afraid to let you know exactly where she stood. The best.
Fun Fact: I remember arguing with her over which of us hated Piggy the most. I was sure I did. She disagreed. It remains unresolved...
November 24, 2025 at 8:15 PM
This is who she was.
Passionate in her beliefs. Fiercely loyal to her friends. Never afraid to let you know exactly where she stood. The best.
Fun Fact: I remember arguing with her over which of us hated Piggy the most. I was sure I did. She disagreed. It remains unresolved...
Passionate in her beliefs. Fiercely loyal to her friends. Never afraid to let you know exactly where she stood. The best.
Fun Fact: I remember arguing with her over which of us hated Piggy the most. I was sure I did. She disagreed. It remains unresolved...
Liu, Y., Zeng, H., Zhao, F. et al. A tiny Cambrian stem-mandibulate reveals independent evolution of limb tagmatization and specialization in early euarthropods. Sci Rep 15, 19115 (2025). doi.org/10.1038/s415...
A tiny Cambrian stem-mandibulate reveals independent evolution of limb tagmatization and specialization in early euarthropods - Scientific Reports
Scientific Reports - A tiny Cambrian stem-mandibulate reveals independent evolution of limb tagmatization and specialization in early euarthropods
doi.org
November 24, 2025 at 8:01 PM
Liu, Y., Zeng, H., Zhao, F. et al. A tiny Cambrian stem-mandibulate reveals independent evolution of limb tagmatization and specialization in early euarthropods. Sci Rep 15, 19115 (2025). doi.org/10.1038/s415...
Gelfo, J.N., Goin, F.J. & Vega, N.A. First unambiguous evidence of Multituberculata from the Late Cretaceous of South America. Sci Rep 15, 41500 (2025). doi.org/10.1038/s415...
First unambiguous evidence of Multituberculata from the Late Cretaceous of South America - Scientific Reports
Scientific Reports - First unambiguous evidence of Multituberculata from the Late Cretaceous of South America
doi.org
November 24, 2025 at 7:57 PM
Gelfo, J.N., Goin, F.J. & Vega, N.A. First unambiguous evidence of Multituberculata from the Late Cretaceous of South America. Sci Rep 15, 41500 (2025). doi.org/10.1038/s415...
Reposted by Thomas R. Holtz, Jr.
Before I left Utah, I rose in the middle of the night to hit my favorite trail at dawn. One last time, at least for a time.
One Last Day in Utah's Slickrock
An job offer out of state called for a melancholy farewell to Arches National Park
www.sierraclub.org
November 24, 2025 at 2:23 PM
Before I left Utah, I rose in the middle of the night to hit my favorite trail at dawn. One last time, at least for a time.
A struggle to survive: Guild hierarchy predicts drought benefit among large carnivores - Balme - Journal of Animal Ecology - Wiley Online Library besjournals.onlinelibrary.wiley.com/doi/10.1111/...
A struggle to survive: Guild hierarchy predicts drought benefit among large carnivores
This study reveals that drought does not uniformly benefit large carnivores. While prey acquisition increased for both leopards and lions, leopard recruitment declined due to higher intraguild predat...
besjournals.onlinelibrary.wiley.com
November 24, 2025 at 1:46 PM
A struggle to survive: Guild hierarchy predicts drought benefit among large carnivores - Balme - Journal of Animal Ecology - Wiley Online Library besjournals.onlinelibrary.wiley.com/doi/10.1111/...
Happy Origin Day! Published OTD in 1859
November 24, 2025 at 1:34 PM
Happy Origin Day! Published OTD in 1859
Eagles - Life In The Fast Lane (Official Audio)
YouTube video by Eagles
youtu.be
November 24, 2025 at 1:15 PM
Reposted by Thomas R. Holtz, Jr.
The 12-month running mean global temperature anomaly continues to fall from its peak (temporary), which is mostly in response to cooler conditions over the equatorial Pacific Ocean during the last year (weak La Niña state).
➡️ Graphic available by zacklabe.com/climate-chan... 🌊⚒️🧪
➡️ Graphic available by zacklabe.com/climate-chan... 🌊⚒️🧪
November 24, 2025 at 1:44 AM
The 12-month running mean global temperature anomaly continues to fall from its peak (temporary), which is mostly in response to cooler conditions over the equatorial Pacific Ocean during the last year (weak La Niña state).
➡️ Graphic available by zacklabe.com/climate-chan... 🌊⚒️🧪
➡️ Graphic available by zacklabe.com/climate-chan... 🌊⚒️🧪
Reposted by Thomas R. Holtz, Jr.
Under RFK Jr, the USDA stopped tracking US hunger just as the Republican shutdown ripped away SNAP for 42M Americans — a data blackout that covers up the cost of MAGA's starvation campaign. MAGA, MAHA — they are all complicit in hurting Americans. #impeachthequack
November 23, 2025 at 3:40 PM
Under RFK Jr, the USDA stopped tracking US hunger just as the Republican shutdown ripped away SNAP for 42M Americans — a data blackout that covers up the cost of MAGA's starvation campaign. MAGA, MAHA — they are all complicit in hurting Americans. #impeachthequack