u/diariosdeljurasico

Hell Creek, 66 million years ago. The ecosystem was not in decline. Triceratops were abundant, hadrosaurs were thriving, and T-Rex sat at the top of it all. Nothing indicated what was coming.

What makes the Chicxulub event so striking is the speed. The impactor hit, the ejecta returned to the atmosphere within hours, and surface temperatures spiked globally before the day was over. An animal like T-Rex — with a home range estimated between 50 and 100 square kilometers — would have had nowhere to go even if it could sense something was wrong.

One question for the community: recent studies suggest T-Rex may have had lips covering its teeth rather than the classic exposed-teeth look. Does the current fossil evidence actually support that, or is it still too preliminary to call?

Link is in our profile.

We just started a new series called Un Día Antes del Fin. The concept is simple: we follow a real animal through a complete day, 24 hours before one of the great mass extinctions. The animal does not know what is coming. Everything looks completely normal.

The first episode follows a male Triceratops through his last day in Hell Creek, 66 million years ago. More than 30% of all dinosaur specimens recovered from Hell Creek belong to Triceratops. It was the dominant animal of its world. Thriving. Successful. And then gone in hours.

The detail that hit hardest in research was how rich and functional that ecosystem was right up to the end. Nothing was in decline. It was a world at its absolute peak. And then the Chicxulub impactor arrived.

One question for the community: the frill color change hypothesis for Triceratops based on vascular network analysis is gaining traction but is not universally accepted. Where does the community stand on the current evidence?

Watch its last 24 hours here: https://youtu.be/jRT-lKWLozs

We just started a new series called Un Día Antes del Fin. The concept is simple: we follow a real animal through a complete day, 24 hours before one of the great mass extinctions. The animal does not know what is coming. Everything looks completely normal.

The first episode follows a male Triceratops through his last day in Hell Creek, 66 million years ago. More than 30% of all dinosaur specimens recovered from Hell Creek belong to Triceratops. It was the dominant animal of its world. Thriving. Successful. And then gone in hours.

The detail that hit hardest in research was how rich and functional that ecosystem was right up to the end. Nothing was in decline. It was a world at its absolute peak. And then the Chicxulub impactor arrived.

One question for the community: the frill color change hypothesis for Triceratops based on vascular network analysis is gaining traction but is not universally accepted. Where does the community stand on the current evidence?

Link is in our profile.

We just started a new series called Un Día Antes del Fin. The concept is simple: we follow a real animal through a complete day, 24 hours before one of the great mass extinctions. The animal does not know what is coming. Everything looks completely normal.

The first episode follows a male Triceratops through his last day in Hell Creek, 66 million years ago. More than 30% of all dinosaur specimens recovered from Hell Creek belong to Triceratops. It was the dominant animal of its world. Thriving. Successful. And then gone in hours.

The detail that hit hardest in research was how rich and functional that ecosystem was right up to the end. Nothing was in decline. It was a world at its absolute peak. And then the Chicxulub impactor arrived.

One question for the community: the frill color change hypothesis for Triceratops based on vascular network analysis is gaining traction but is not universally accepted. Where does the community stand on the current evidence?

Link is in our profile.

Most people assume T-Rex was the dominant predator of the Cretaceous in every category. But the speed comparison between T-Rex and Carnotaurus is genuinely interesting and the evidence does not clearly favor the T-Rex.

The caudofemoral muscles in Carnotaurus were extraordinarily developed relative to body mass. These muscles connect the tail to the hind legs and are the primary driver of speed in theropods. Carnotaurus had a proportionally longer tail with more muscle mass dedicated to locomotion than T-Rex.

Current biomechanical estimates put Carnotaurus at between 45 and 56 kilometers per hour for short bursts. T-Rex estimates range from 17 to 29 kilometers per hour depending on the study. The gap is significant.

The counterargument is body mass. T-Rex was significantly heavier and the energetic cost of acceleration scales with mass. Carnotaurus at 2 tons could theoretically reach top speed much faster than T-Rex at 8 tons.

They never shared the same ecosystem. T-Rex was North American, Carnotaurus was Patagonian. But the comparison still matters for understanding the different evolutionary strategies large theropods developed in isolation.

Where does the community stand on the current speed estimates for both animals? And does the strike and retreat hunting model for Carnotaurus change how we think about what speed actually meant for a predator of its size?

We covered this in detail in our latest episode. The answer is in our profile.

Most people assume T-Rex was the dominant predator of the Cretaceous in every category. But the speed comparison between T-Rex and Carnotaurus is genuinely interesting and the evidence does not clearly favor the T-Rex.

The caudofemoral muscles in Carnotaurus were extraordinarily developed relative to body mass. These muscles connect the tail to the hind legs and are the primary driver of speed in theropods. Carnotaurus had a proportionally longer tail with more muscle mass dedicated to locomotion than T-Rex.

Current biomechanical estimates put Carnotaurus at between 45 and 56 kilometers per hour for short bursts. T-Rex estimates range from 17 to 29 kilometers per hour depending on the study. The gap is significant.

The counterargument is body mass. T-Rex was significantly heavier and the energetic cost of acceleration scales with mass. Carnotaurus at 2 tons could theoretically reach top speed much faster than T-Rex at 8 tons.

They never shared the same ecosystem. T-Rex was North American, Carnotaurus was Patagonian. But the comparison still matters for understanding the different evolutionary strategies large theropods developed in isolation.

Where does the community stand on the current speed estimates for both animals? And does the strike and retreat hunting model for Carnotaurus change how we think about what speed actually meant for a predator of its size?

We covered this in detail in our latest episode. The answer is in our profile.

Episode 7 of Diarios del Jurásico is out. We follow Sol, an adult male Pteranodon, through a complete day over the Western Interior Seaway 85 million years ago.

The thing that surprised us most in research was the locomotion debate. Pteranodon on the ground is genuinely strange. The current consensus is quadrupedal launch using all four limbs, with the wing membrane folded against the body. But the exact mechanics of how an animal with a 7 meter wingspan stood, walked and launched from flat ground is still being worked out.

The other thing we spent a lot of time on was the crest. The size difference between male and female crests is one of the clearest examples of sexual dimorphism in the pterosaur fossil record. The largest crests are so disproportionate that pure display function seems like the only explanation that makes sense biomechanically.

We would genuinely love to know what this community thinks is the most underrated aspect of Pteranodon biology. The locomotion question is ours. What is yours?

Did you know any of these?

1. The tail club of an Ankylosaurus could generate enough force to shatter the leg bones of a T-Rex. Paleontologists have found T-Rex bones with fracture patterns consistent with exactly this kind of impact. The herbivore was fighting back and winning.
2. Its armor was not attached to the skeleton. The osteoderms, the bony plates covering its body, were embedded directly into the skin. If you found an Ankylosaurus skeleton without the skin preserved, most of the armor would be missing entirely.
3. It had a brain roughly the size of a walnut for a body weighing up to 8 tons. Yet it survived alongside T-Rex for millions of years. Intelligence was never the strategy. The strategy was being completely impossible to kill.
4. Its eyelids were armored. Actual bone over the eyes. T-Rex had the most powerful bite force of any land animal ever recorded and still could not get through the defenses of a healthy adult Ankylosaurus.
5. Ankylosaurus was one of the last non-avian dinosaurs to ever exist. It was alive right up to the asteroid impact 66 million years ago. It did not go extinct because something beat it. Nothing ever beat it. The asteroid ended a winning streak that had lasted millions of years.

Which of these surprised you most? We covered a full day in the life of an Ankylosaurus in detail — you can find that video in the pinned post on our profile.

Episode 5 of Diarios del Jurásico is out. We follow Kael, an adult male Spinosaurus, through a complete day of survival in the rivers of Cretaceous North Africa, 95 million years ago.

14 meters long. Semi-aquatic. The largest carnivorous dinosaur ever known. And yet one of the most misunderstood.

Video is linked in our profile. Watch it to the end, drop a like if you enjoy it and leave your thoughts in the YouTube comments. We read every single one.

Did you know any of these?

1. Its heart is estimated to have weighed close to a ton. It had to pump blood almost 12 meters upward to reach the brain. No living animal comes close to this cardiovascular challenge.
2. Its neck alone was around 9 meters long. That is taller than a three-story building. And it held it at a steep upward angle, not horizontally like older reconstructions showed.
3. It could strip an enormous arc of foliage without moving its body at all, simply by sweeping its neck sideways. This gave it a completely unique feeding advantage over every other sauropod sharing the same habitat.
4. Despite weighing up to 55 tons, its bones were hollow and filled with air sacs. The entire skeleton weighed a fraction of what you would expect. This pneumaticity is what allowed it to reach this size at all.
5. If a Brachiosaurus floated in water, its neck would act as a buoyant counterweight keeping its head permanently above the surface. It physically could not submerge its own head while floating.

Which of these surprised you most? And feel free to ask anything else about Brachiosaurus or any other prehistoric animal in the comments. You can also reach me directly through my profile.

Did you know any of these?

1. Its heart is estimated to have weighed close to a ton. It had to pump blood almost 12 meters upward to reach the brain. No living animal comes close to this cardiovascular challenge.
2. Its neck alone was around 9 meters long. That is taller than a three-story building. And it held it at a steep upward angle, not horizontally like older reconstructions showed.
3. It could strip an enormous arc of foliage without moving its body at all, simply by sweeping its neck sideways. This gave it a completely unique feeding advantage over every other sauropod sharing the same habitat.
4. Despite weighing up to 55 tons, its bones were hollow and filled with air sacs. The entire skeleton weighed a fraction of what you would expect. This pneumaticity is what allowed it to reach this size at all.
5. If a Brachiosaurus floated in water, its neck would act as a buoyant counterweight keeping its head permanently above the surface. It physically could not submerge its own head while floating.

Which of these surprised you most? And feel free to ask anything else about Brachiosaurus or any other prehistoric animal in the comments. You can also reach me directly through my profile.

We ran a poll last week asking which dinosaur people found most endearing and Ankylosaurus won with 40% of the vote. Apparently an armored tank with a bone-crushing tail has a lot of charm.

Now the harder question: which dinosaur would you actually least want to encounter?

🔴 T-Rex — 3,600 kg of bite force. No debate.
🟡 Spinosaurus — 14 meters, semi-aquatic, total predator.
🟢 Ankylosaurus — a tail that fractured T-Rex bones.
🔵 Triceratops — three one-meter horns and 12 tons behind them.

If you vote on our YouTube community poll it genuinely helps us understand what our audience wants to see next. Your votes shape the direction of the channel. The poll is in the pinned post on our profile.

We ran a poll last week asking which dinosaur people found most endearing and Ankylosaurus won with 40% of the vote. Apparently an armored tank with a bone-crushing tail has a lot of charm.

Now the harder question: which dinosaur would you actually least want to encounter?

🔴 T-Rex — 3,600 kg of bite force. No debate.
🟡 Spinosaurus — 14 meters, semi-aquatic, total predator.
🟢 Ankylosaurus — a tail that fractured T-Rex bones.
🔵 Triceratops — three one-meter horns and 12 tons behind them.

If you vote on our YouTube community poll it genuinely helps us understand what our audience wants to see next. Your votes shape the direction of the channel. The poll is in the pinned post on our profile.

We are running a poll on our YouTube community tab and wanted to bring the question here too since this community probably has strong opinions.

The options: Stegosaurus with its mysterious plates and walnut brain, Ankylosaurus who was essentially an armored tank that just wanted to eat ferns, Brachiosaurus who was simply too large to worry about anything, or Carnotaurus with its horns and genuinely ridiculous arm situation.

Not asking about the most dangerous or most famous. Asking which one you would actually want to spend a day with if it were somehow harmless.

To vote on the actual poll, head to our profile and click the community tab link there.

We are running a poll on our YouTube community tab and wanted to bring the question here too since this community probably has strong opinions.

The options: Stegosaurus with its mysterious plates and walnut brain, Ankylosaurus who was essentially an armored tank that just wanted to eat ferns, Brachiosaurus who was simply too large to worry about anything, or Carnotaurus with its horns and genuinely ridiculous arm situation.

Not asking about the most dangerous or most famous. Asking which one you would actually want to spend a day with if it were somehow harmless.

To vote on the actual poll, head to our profile and click the community tab link there.

We are running a poll on our YouTube community tab and wanted to bring the question here too since this community probably has strong opinions.

The options: Stegosaurus with its mysterious plates and walnut brain, Ankylosaurus who was essentially an armored tank that just wanted to eat ferns, Brachiosaurus who was simply too large to worry about anything, or Carnotaurus with its horns and genuinely ridiculous arm situation.

Not asking about the most dangerous or most famous. Asking which one you would actually want to spend a day with if it were somehow harmless.

To vote on the actual poll, head to our profile and click the community tab link there.

For most of the 20th century large sauropods were reconstructed as primarily aquatic animals. This hypothesis has been largely abandoned and the evidence against it is solid. Limb bone density, foot structure and musculature all point to a fully terrestrial animal.

But I want to push on this a bit. The complete rejection of any water entry seems like overcorrecting. Modern elephants wade regularly. The question of whether Brachiosaurus could occasionally enter water seems different from whether it was primarily aquatic.

The cardiovascular angle is interesting too. A heart estimated at close to a ton pumping blood 12 meters upward on land is already extraordinary. What would the pressure dynamics look like partially submerged? Does buoyancy help or create new circulatory problems?

Is there modern work on occasional versus primary aquatic behavior in large sauropods? And is the complete rejection of water entry actually supported by evidence or partly a reaction against the old hypothesis going too far?

For most of the 20th century large sauropods were reconstructed as primarily aquatic animals. This hypothesis has been largely abandoned and the evidence against it is solid. Limb bone density, foot structure and musculature all point to a fully terrestrial animal.

But I want to push on this a bit. The complete rejection of any water entry seems like overcorrecting. Modern elephants wade regularly. The question of whether Brachiosaurus could occasionally enter water seems different from whether it was primarily aquatic.

The cardiovascular angle is interesting too. A heart estimated at close to a ton pumping blood 12 meters upward on land is already extraordinary. What would the pressure dynamics look like partially submerged? Does buoyancy help or create new circulatory problems?

Is there modern work on occasional versus primary aquatic behavior in large sauropods? And is the complete rejection of water entry actually supported by evidence or partly a reaction against the old hypothesis going too far?

For most of the 20th century large sauropods were reconstructed as primarily aquatic animals. This hypothesis has been largely abandoned and the evidence against it is solid. Limb bone density, foot structure and musculature all point to a fully terrestrial animal.

But I want to push on this a bit. The complete rejection of any water entry seems like overcorrecting. Modern elephants wade regularly. The question of whether Brachiosaurus could occasionally enter water seems different from whether it was primarily aquatic.

The cardiovascular angle is interesting too. A heart estimated at close to a ton pumping blood 12 meters upward on land is already extraordinary. What would the pressure dynamics look like partially submerged? Does buoyancy help or create new circulatory problems?

Is there modern work on occasional versus primary aquatic behavior in large sauropods? And is the complete rejection of water entry actually supported by evidence or partly a reaction against the old hypothesis going too far?