Griffin Lab
@griffinlabpaleo.bsky.social
Origin of major clades, ontogeny & evolution of form, evo+devo+paleo — Dept of Geosciences at Princeton University
So the Nanotyrannus type specimen is full-size, or nearly so. We discuss more in the paper why we don’t find it likely that this is simple intraspecific variation in T. rex, sexual dimorphism, or a congenital dwarfism. The best explanation is that Nanotyrannus is distinct from Tyrannosaurus (9/12)
December 4, 2025 at 7:02 PM
So the Nanotyrannus type specimen is full-size, or nearly so. We discuss more in the paper why we don’t find it likely that this is simple intraspecific variation in T. rex, sexual dimorphism, or a congenital dwarfism. The best explanation is that Nanotyrannus is distinct from Tyrannosaurus (9/12)
This is especially apparent when we compare to a juvenile T. rex hyoid from the LACM. Despite being smaller in size, the Nano hyoid shows a close package of external growth marks that is the classic indicator of skeletal maturity (8/12)
December 4, 2025 at 7:02 PM
This is especially apparent when we compare to a juvenile T. rex hyoid from the LACM. Despite being smaller in size, the Nano hyoid shows a close package of external growth marks that is the classic indicator of skeletal maturity (8/12)
All that was left was to test the Nanotyrannus type specimen, the skull that formally defines the species Nanotyrannus lancensis. At the time, it was the general consensus that Nano was a juvenile T. rex, so we were surprised to find every indication of maturity in the hyoid (7/12)
December 4, 2025 at 7:02 PM
All that was left was to test the Nanotyrannus type specimen, the skull that formally defines the species Nanotyrannus lancensis. At the time, it was the general consensus that Nano was a juvenile T. rex, so we were surprised to find every indication of maturity in the hyoid (7/12)
Then, we had to establish that it worked in extinct dinosaurs, especially large theropods. Running the size gamut from Coelophysis to Allosaurus to two definitive Tyrannosaurus individuals, we showed that hyoid microstructure works well! Not quite as precise as limbs, but it gets the job done (6/12)
December 4, 2025 at 7:02 PM
Then, we had to establish that it worked in extinct dinosaurs, especially large theropods. Running the size gamut from Coelophysis to Allosaurus to two definitive Tyrannosaurus individuals, we showed that hyoid microstructure works well! Not quite as precise as limbs, but it gets the job done (6/12)
First, we had to establish that hyoid histology worked to gauge maturity in living relatives of dinosaurs of known growth stages. We showed that it did, in a growth series of Ostrich, Alligator, and even a Dwarf Caiman. Step one, done! (5/12)
December 4, 2025 at 7:02 PM
First, we had to establish that hyoid histology worked to gauge maturity in living relatives of dinosaurs of known growth stages. We showed that it did, in a growth series of Ostrich, Alligator, and even a Dwarf Caiman. Step one, done! (5/12)
The Nano skull does have ‘hyoids’, tubular throat bones. During a visit to the Cleveland Museum of Natural History, curator Caitlin Colleary and I wondered if these might also contain a record of growth, and allow us to directly test maturity in the name-bearing specimen (4/12)
December 4, 2025 at 7:02 PM
The Nano skull does have ‘hyoids’, tubular throat bones. During a visit to the Cleveland Museum of Natural History, curator Caitlin Colleary and I wondered if these might also contain a record of growth, and allow us to directly test maturity in the name-bearing specimen (4/12)
The best way to tell a dinosaur’s maturity is by looking at the bone microstructure (histology) of limb bones. However, the type specimen of Nanotyrannus is an isolated skull, so this method wasn’t viable. This difficulty resulted in the longest-running current debate in dinosaur paleontology (3/12)
December 4, 2025 at 7:02 PM
The best way to tell a dinosaur’s maturity is by looking at the bone microstructure (histology) of limb bones. However, the type specimen of Nanotyrannus is an isolated skull, so this method wasn’t viable. This difficulty resulted in the longest-running current debate in dinosaur paleontology (3/12)
There has been a debate since the skull’s discovery in 1942: whether Nano was a small-bodied tyrannosaur that lived with Tyrannosaurus, or just a juvenile T. rex. This has major implications for how we understand T. rex growth and carnivores within last ecosystems to host non-bird dinosaurs (2/12)
December 4, 2025 at 7:02 PM
There has been a debate since the skull’s discovery in 1942: whether Nano was a small-bodied tyrannosaur that lived with Tyrannosaurus, or just a juvenile T. rex. This has major implications for how we understand T. rex growth and carnivores within last ecosystems to host non-bird dinosaurs (2/12)
Hess Postdoctoral Fellow Steph Lechki speaking about energetic fitness models to finish out the last day of SVP!
November 15, 2025 at 2:02 PM
Hess Postdoctoral Fellow Steph Lechki speaking about energetic fitness models to finish out the last day of SVP!
PhD student @lnwilson.bsky.social showing new methods for imaging embryonic bird tissues in 3D
November 15, 2025 at 11:12 AM
PhD student @lnwilson.bsky.social showing new methods for imaging embryonic bird tissues in 3D
@princeton.edu Presidential postdoc Will Reyes speaking at #2025SVP on the growth and development of extinct crocodilian relatives
November 13, 2025 at 9:49 AM
@princeton.edu Presidential postdoc Will Reyes speaking at #2025SVP on the growth and development of extinct crocodilian relatives
Had a wonderful visit from collaborator Tatsuya Hirasawa from the U of Tokyo! We’ve been awarded a joint Princeton-Tokyo grant to exchange exciting new techniques in vertebrate evo-devo. Our visit to Japan will happen in March!
October 28, 2025 at 11:16 PM
Had a wonderful visit from collaborator Tatsuya Hirasawa from the U of Tokyo! We’ve been awarded a joint Princeton-Tokyo grant to exchange exciting new techniques in vertebrate evo-devo. Our visit to Japan will happen in March!
It’s starting to appear! Here’s the underside of the croc’s “chin”, the end of the lower jaw
October 24, 2025 at 6:04 PM
It’s starting to appear! Here’s the underside of the croc’s “chin”, the end of the lower jaw
Opening a field jacket in the new prep lab! Preparator Jack Wilson will work his way through the matrix to the croc skull hiding inside
October 20, 2025 at 9:54 PM
Opening a field jacket in the new prep lab! Preparator Jack Wilson will work his way through the matrix to the croc skull hiding inside
Had a great visit at Oklahoma State, thanks @fmachado.bsky.social for the invite and for all your hospitality!
September 13, 2025 at 6:31 PM
Had a great visit at Oklahoma State, thanks @fmachado.bsky.social for the invite and for all your hospitality!
An American alligator embryo roughly 13 days after the egg was laid
June 20, 2025 at 8:12 PM
An American alligator embryo roughly 13 days after the egg was laid
We do something similar, but with Falcon tubes. The bases have the tube’s cap glued into them and fit on Xradia scanner chucks. The Falcon tubes themselves can then be screwed onto the whole contraption, making switching out tube-mounted samples quick & easy
June 15, 2025 at 5:18 PM
We do something similar, but with Falcon tubes. The bases have the tube’s cap glued into them and fit on Xradia scanner chucks. The Falcon tubes themselves can then be screwed onto the whole contraption, making switching out tube-mounted samples quick & easy
Hugely successful alligator egg run down to Rockefeller Wildlife Refuge in Louisiana—we’ll incubate these 250 eggs back in the lab to answer questions about archosaurian development and evolution
June 15, 2025 at 12:56 PM
Hugely successful alligator egg run down to Rockefeller Wildlife Refuge in Louisiana—we’ll incubate these 250 eggs back in the lab to answer questions about archosaurian development and evolution
Great presentations today at the Princeton Catalysis Initiative symposium—this initiative funds many cross-disciplinary projects across Princeton, including our lab’s work
May 20, 2025 at 6:14 PM
Great presentations today at the Princeton Catalysis Initiative symposium—this initiative funds many cross-disciplinary projects across Princeton, including our lab’s work
Now that it’s nice out, we can spend some time poking around local outcrop
May 18, 2025 at 11:14 PM
Now that it’s nice out, we can spend some time poking around local outcrop
The new labs in the new building are almost finished! We should move into the new space in a little over a month.
May 10, 2025 at 7:33 PM
The new labs in the new building are almost finished! We should move into the new space in a little over a month.
When you get a dud ostrich egg, it should at least be used for something—like lab breakfast-for-dinner!
May 5, 2025 at 7:53 PM
When you get a dud ostrich egg, it should at least be used for something—like lab breakfast-for-dinner!
@lnwilson.bsky.social opened her first (of many) ostrich eggs today
May 1, 2025 at 6:03 PM
@lnwilson.bsky.social opened her first (of many) ostrich eggs today
Thanks to @paleofox.bsky.social for the visit and seminar, blowing our minds with the weird and wonderful world of bird lungs
April 30, 2025 at 2:01 PM
Thanks to @paleofox.bsky.social for the visit and seminar, blowing our minds with the weird and wonderful world of bird lungs