Tim Demko
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Tim Demko
@timdemko.xyz
3.3K followers 6.2K following 880 posts
Geologist interested in the energy transition, bicycling, and public service

https://bio.link/timdemko

https://orcid.org/0000-0002-9125-0907

https://www.semanticscholar.org/author/Timothy-Michael-Demko/15743754
Posts Replies Media Videos
Reposted by Tim Demko
andersonmineral.bsky.social
A pretty little bivalve shell of the Pecten genus from Dublin. #FossilFriday ⚒️🧪
Fossil shell of a bivalve that has a rounded edge that then has ridges going to a central point on the opposite outer edge. The rock is grey on a beige background with a label with number 9 next to it. At the National Museum of Ireland.
October 2, 2026 at 11:00 AM
Reposted by Tim Demko
aldpaleo.bsky.social
For this #FossilFriday a section of the early #fern Diplolabis from the early Carboniferous showing beautifully preserved tissues 🌿⛏️ (proposed reconstruction from doi.org/10.1016/j.re...) #Paleobotany #botany
Section of a fossil fern axis with preserved tissues, showing the X shaped vascular tissues. The axis is a few in diameter. A reconstruction of the plant by Phillips and Galtier 2005 is shown in a corner
October 2, 2026 at 11:13 AM
Reposted by Tim Demko
ichnologist.bsky.social
For #FossilFriday, a sampling of Late Cretaceous dinosaur footprints preserved as natural casts & attributed to hadrosaurs, but ranging from teeny-tiny to less teeny. On display at the Prehistoric Museum, Utah State University, Price, UT. 🧪🪨🦖🐾
A series of hadrosaur (dinosaur) tracks on display, preserved as dark-gray natural casts, with six on a shelf above arranged—from right to left—in order from smallest to largest on an upper shelf, then two larger tracks on a shelf below.
October 2, 2026 at 11:29 AM
Reposted by Tim Demko
callanbentley.bsky.social
New video!
On the ground in Shenandoah National Park, I check out some structures built by the Civilian Conservation Corps that feature 𝘚𝘬𝘰𝘭𝘪𝘵𝘩𝘰𝘴-bearing blocks of Antietam Formation quartz sandstone (one of which shows spectacular deformation):
youtu.be/lKjQ9_B7u9A
⚒️
Skolithos trace fossils in Civilian Conservation Corps structures, Shenandoah National Park
YouTube video by Callan Bentley
youtu.be
October 1, 2026 at 12:24 PM
Reposted by Tim Demko
jakeberv.bsky.social
46.4866001, -87.6546617
September 30, 2026 at 2:06 AM
Reposted by Tim Demko
vickyveritas.bsky.social
Boudinage are one of the most spectacular geologic structures and some of my favorite rocks. The boudins are the eye-shaped lenses of rock wedged between the white quartz layers. This happened when the rocks were being stretched by tectonic forces. The eye-shaped lenses, augen… 👇🏼

#MinCup26
Boudins of amphibolite layers (metamorphosed basalts) that were stretched between quartz schists (Norway). Photo credits: Haakon Fossen.
October 1, 2026 at 1:49 PM
Reposted by Tim Demko
nhmbryozoa.bsky.social
Published today and fully Open Access:
doi.org/10.1017/jpa....
The fossil record of bioerosion | Journal of Paleontology | Cambridge Core
The fossil record of bioerosion
doi.org
October 1, 2026 at 4:16 PM
Reposted by Tim Demko
friedmanlab.bsky.social
Teaching on the main campus so no collections work today. So here's Bothriolepis canadensis (UMMP VP 3475) from this week's lab for the vertebrate paleontology course.
Bony armor of a placoderm fish with tiny eyes. The fossil is dark in color and shaped like an egg.
October 1, 2026 at 8:54 PM
Reposted by Tim Demko
jvh-vt.bsky.social
Fantastic detail in this 1920 OS map: inclines, railways & mill buildings surrounding Blaenau #Ffestiniog, #Wales. #geology #thestoryofslate
October 1, 2026 at 8:02 PM
Reposted by Tim Demko
extinctmonsters.bsky.social
Well this is bleak. And why did they wait a week after the news leaked just to say "we have no plan?"
September 28, 2026 at 11:28 PM
Reposted by Tim Demko
brandontbishop.bsky.social
This is going to be *so* destructive to North American paleontology, for both the Cretaceous Interior Seaway and Neogene mammals.

All because of state-level ideologies that hold tax cuts and slashing spending are the only thing that can ever be done.
extinctmonsters.bsky.social Ben Miller @extinctmonsters.bsky.social · 3d
Well this is bleak. And why did they wait a week after the news leaked just to say "we have no plan?"
kwch.com @kwch12 @kwch.com · 3d
BREAKING: The Sternberg Museum in Hays will be closing before the end of the year.
September 29, 2026 at 1:59 AM
Reposted by Tim Demko
andrejpaleo.bsky.social
Updated Fossilworks
🧪⚒️ #Geology #Paleobio #EvoBio
johnalroy.bsky.social John Alroy @johnalroy.bsky.social · 27d
The Fossilworks database is now integrated with the Ecological Register and includes growing datasets on Cenozoic and Cretaceous vertebrates including mammals and dinosaurs. All of the 5000+ site inventories include specimen counts used to obtain GW species richness estimates. fossilworks.org
Fossilworks dinosaur map
September 26, 2026 at 7:37 PM
Reposted by Tim Demko
alexisrastier.bsky.social
What an extraordinary journey to Münster (Germany) for the European Paleobotanical and Palynological Conference (EPPC) 🌿 I was honored to present my research at the Early Career Symposium on a new whole-plant reconstruction of a rhacophytalean fern from Bjørnøya.🇳🇴⚒️
#Paleobotany #Devonian #Fern #EPPC
September 26, 2026 at 5:30 AM
Reposted by Tim Demko
bgs.ac.uk
The BGS maps portal provides access to over 45,000 high-res viewing images of almost all maps produced by BGS since mapping started in 1832.

This sheet is from 1852. It shows North part of Anglesey, and part of Holyhead Island Mineral Lodes.

Access the portal: www.bgs.ac.uk/information-...
September 26, 2026 at 7:00 AM
Reposted by Tim Demko
andyfarke.bsky.social
Fossils as cultural heritage: Scientific, commercial and legislative issues - Fanti - 2026 - Geology Today - Wiley Online Library onlinelibrary.wiley.com/doi/full/10....
Fossils as cultural heritage: Scientific, commercial and legislative issues
Fossils are among the principal sources for understanding the history of life through ‘Deep Time’ and can inform projections of biotic responses to environmental change. Despite a widespread recognit...
onlinelibrary.wiley.com
September 24, 2026 at 4:52 PM
Reposted by Tim Demko
callanbentley.bsky.social
Shrimp!
Cenomanian (earliest Late Cretaceous), of Lebanon.
⚒️
Darker brown shrimp fossil.in tan limestone, with a white fracture running through it.
September 24, 2026 at 5:39 PM
Reposted by Tim Demko
patrickwyman.bsky.social
Outstanding new review of ALL of the currently available DNA evidence for the peopling of the Americas, led by Bethany Potter (and the amazing @jenniferraff.bsky.social!): www.sciencedirect.com/science/arti...
www.sciencedirect.com
September 24, 2026 at 2:42 AM
Reposted by Tim Demko
drwendyrocks.bsky.social
Cool girls have cool jobs 😎
September 24, 2026 at 3:11 AM
Reposted by Tim Demko
satellitesci.bsky.social
It's been a long time in the making, but our new #opensource paper has just been published in Remote Sensing of Environment! 🛰️🎉

"Time and tide: Mapping the changing 3D shape of Australia's dynamic intertidal zone using time series satellite data"

www.sciencedirect.com/science/arti...
Scientific figure showing DEA Intertidal outputs
September 24, 2026 at 4:23 AM
Reposted by Tim Demko
haroldtobin.bsky.social
Back from a 5 day backpacking-as-field-work venture into the Olympic mountains interior. We covered 45 miles on the Skyline Ridge trail and back, with 16,000 feet of total vertical in 5 days. All to recon another swath of deeply subducted rocks from the paleo-seismogenic zone. Subduction rocks! ⚒️
Two geologists hiking along steep bare hillside seen from behind, with distant moountain ridge and blue sky. Close up shot of rock outcrop of severely deformed meta-sedimentary rocks with a block-in-matrix melange fabric. Pencil shown for scale. Geologist standing at dusk against a rocky landscape, brushing their teeth with a headlamp on. Person stands on rocky knob against blue skyline with Mt. Olympus (Washington) in background.
September 24, 2026 at 5:49 AM
Reposted by Tim Demko
davepetley.bsky.social
A new paper (He et al. 2026) in the journal Landslides describes the breach of the massive Matai'an Rover landslide dam in Taiwan in September 2025, which killed 24 people.
eos.org/thelandslide...
The aftermath of the Matai'an landslide dam breach. Image using images from Planet Labs, from He et al. (2025).
September 24, 2026 at 7:14 AM
Reposted by Tim Demko
akufner.bsky.social
This one has been a long time coming! I'm happy to share that another chapter of my PhD has been published!

In this one, I'm shaking up the taxonomy of North American metoposaurids. This work was largely done in museum collections, and more on that below.

peerj.com/articles/217...
A figure with maps showing the distribution of metoposaurid occurrences in Upper Triassic outcrops of western and eastern North America (centered on the USA). The approximate chronostratigraphic ranges of the now five recognized species are plotted, and line drawings of all of the potentially or definitively diagnostic holotypes of North American metoposaurids are included.
September 23, 2026 at 9:07 PM
Reposted by Tim Demko
moreorloess.bsky.social
Beach ridge complex and dunes at Pointe aux Chenes, Michigan. I've got it in my slides for a case study on post-glacial rebound and other causes of lake level change on the Great Lakes, and I had to post it here again.
A shaded relief map of a very impressive set of concentric beach rdiges, and on the west side a coastal dune field, along the shore of northern Lake Michigan.
September 24, 2026 at 1:31 AM
Reposted by Tim Demko
asrivkin.bsky.social
The answer is “samples from sites specifically chosen as having young lunar basalts (as estimated from crater counts) to serve as benchmarks to make the lunar dating system, and thus inner solar system age estimates, more accurate and robust”.

(cc @barbylon.bsky.social)
September 22, 2026 at 2:11 PM
Reposted by Tim Demko
celestelabedz.bsky.social
It's been so sad watching my alma mater in the last decade, especially as the Earth and atmospheric science department was eliminated.

Nebraskans (and the world!) deserve long-term investment that builds great education and research in Nebraska.
aaup.org AAUP @aaup.org · 9d
"The elimination of entire departments to achieve relatively modest short-term savings risks long-term damage to research capacity, student enrollment, and institutional reputation." – Todd Wolfson, AAUP President
Faculty group urges AAU to deny UNL readmission over budget cuts
The American Association of University Professors called the University of Nebraska-Lincoln's push to gain readmission to the AAU into question following last year's program and position eliminations.
journalstar.com
September 22, 2026 at 4:52 PM