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Posted by marojejian 5 days ago

T. Rex Had a Body Temperature of 97°F(www.nytimes.com)
gift link: https://www.nytimes.com/2026/09/16/science/trex-dinosaur-tem...

paper: https://www.science.org/doi/10.1126/sciadv.aeb7653

71 points | 124 comments
micromacrofoot 5 days ago|
> Up until the early 2000s, dinosaurs were thought to be rather reptilian and therefore probably coldblooded, Dr. Wiemann said. That began to change as multiple lines of evidence from geochemistry studies and CT scans of fossils showed they were warm-blooded. Dr. Wiemann had previously found that T. rex had a fast metabolism, but she said the new study did an “exquisite” job of zeroing in on a precise body temperature.

> To take the body temperature of a long extinct, school-bus-size predator, scientists at the University of California, Los Angeles, used a clever geochemistry technique on fossilized teeth, including two from “Thomas,” a famous T. rex in the collection of the National History Museum of Los Angeles County.

fascinating

we've also learned more about the air at the time via teeth, https://nautil.us/the-data-in-a-dinos-smile-1229729

SoftTalker 5 days ago|
It intuitively makes sense. A cold-blooded creature of that mass would take a long time to properly warm up or cool down. Most modern cold-blooded animals are small, e.g. frogs, snakes, lizards. They can move into the sunlight or shade as needed and pretty quickly change temperature.
code_biologist 5 days ago||
Repost from a different thread: Related only topically, a 1hr YouTube talk I enjoyed a lot: "Hatchling T. rex and the Evolution of Vertebrate Parental Care" by Nick Longrich: https://www.youtube.com/watch?v=zd0dR2n9hLA

He's a paleontologist and the talk starts with some pretty interesting statistical analysis aiming to estimate T rex clutch sizes (66 eggs) and hatchling weights (1.5kg) as well as T rex parental care. It ends with looking at evolutionary history trends in increasing parental investment in radically different animals.

He talks a little slow, so a little playback speed bump won't go amiss.

laweijfmvo 5 days ago||
How do we know its body temperature was 97 degrees, and simply not the environment was 97 degrees?
altcognito 5 days ago||
They compared against crocodilian teeth and those teeth were at a different temperature. Crocodilian teeth are known to be at a similar temperature to their environment because they are known to be cold blooded.

It is correct to say that we don't know they were warm blooded, just that their body temps were likely the given observed temperature.

laweijfmvo 3 days ago||
i assume this means crocodiles from the same time period?
cwmma 5 days ago|||
If it was environmental then you'd expect it to fluctuate over time, but they also checked it against an animal they knew to be cold blooded, if it was environmental you'd expect them to be the same, but that animal was calculated by the same method to be colder.
pixl97 5 days ago|||
What environment would stay at a constant 97 degrees?
surgi 5 days ago||
Europe this summer? /jk
hulitu 2 days ago|||
They measured it. Thanks to AI, we can measure things today which would not have been possible 2 millions years ago. /s
b0rtb0rt 5 days ago||
[flagged]
lirolero 4 days ago||
[flagged]
strongwaddle 5 days ago||
'Hotter than a crocodile, cooler than a chickennnnn....'

is the opening line to a great song i'll never get to hear.

dpe82 5 days ago||
The slop generator's gotchu: https://suno.com/s/gT2YhaQyNdlkzgeU
zem 5 days ago|||
scans roughly to "macarena" if that helps (:
ChrisRR 5 days ago|||
Not yet a woman
p1mrx 5 days ago||
With the power of AI slop, you can hear anything: https://pmarks.net/posted_links/trex_ai.mp3
em-bee 5 days ago|||
waiting for the video by neural derp like this one: https://youtu.be/lS6dtRWXF1o
vardump 5 days ago|||
Can you share the prompt?
p1mrx 5 days ago||
Claude Sonnet 5 on openrouter.ai/chat

> Write a song about the T-rex. First line "Hotter than a crocodile, cooler than a chicken". Format for aisonggenerator.io.

Then I copied the output to aisonggenerator.io (1 free song per day), and used Audacity/Tenacity to record the MP3 because they make you pay to download.

vardump 4 days ago||
Thanks!
ChrisMarshallNY 5 days ago||
Wouldn't be surprised if the smaller raptors had even higher body temps.
layer8 5 days ago||
Seems sensible, given that birds have higher body temperatures.
hedgehog 5 days ago||
I didn't know this so I looked up the number for farm chickens, according to University of Kentucky (seems appropriate) they have a body temperature of "between 105°F and 107°F (40.6° and 41.7°C) ... Smaller chicken breeds have a higher body temperature than larger breeds"

https://afs.mgcafe.uky.edu/poultry/chapter-7-air-temperature

Obscurity4340 4 days ago||
I wish raptors could be reanimated and made in miniature so you could have little Raptor domestici (house raptors) running around causing all kinds of hijinks
manarth 3 days ago|||
The cassowary is here and alive today, but you wouldn't want of them in your backyard!
ChrisMarshallNY 4 days ago|||
I think many of them were about the size of turkeys.

Velociraptor was quite small. Jurassic Park used Utahraptor, or Deinonychus as a model.

ohyoutravel 5 days ago||
This is really interesting, worth a read. Wouldn’t be surprised if the even larger dinosaurs had even higher body temps!
SP3269 5 days ago||
I’m missing Marc Bolan.
fsckboy 5 days ago|
is it you, metal guru?
b0rtb0rt 5 days ago||
the best part of this kind of science is that there’s no way to reproduce it or prove if it’s actually true, but it makes a great pop science article
modzu 5 days ago|
id assumed as much since seeing jurassic park in 1996
kilroy123 5 days ago|
It's actually older, from 1993.
dofm 5 days ago||
It's in the book. So 1990.

Internet says the inspiration for Alan Grant is Robert Bakker, and his first writings on it were in 1968:

https://en.wikipedia.org/wiki/Robert_T._Bakker

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