THE REPTIPAGE

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For a primer on this blog series and an FAQ, see here.

This episode features advisement by the following paleontology consultants:

• Steve Brusatte
• Alexander Farnsworth
• Kiersten Formoso
• Michael Habib
• Scott Hartman
• John Hutchinson
• Luke Muscutt
• Peter Skelton
• Robert Spicer
• Paul Valdes
• Mark Witton
• Darren Naish

Scene 1: Tyrannosaurus rex with hatchlings

Baseless speculation

Filamented mohawk of Tyrannosaurus rex

This is basically anti-scientific at this point.

Downy hatchlings of T. rex

As described numerous times before, this requires T. rex to switch integument as it grows up. This is something that no vertebrate is known to do.

Hatchlings won’t shut up

Get used to this complaint. It’s the standard problem with all these prehistoric fictions. The dinosaurs always have to be making some sort of noise.

Hatchlings are hyper-inquisitive and easily distracted

This is just a very mammal-centric interpretation of how a hatchling / juvenile dinosaur would act. I would have much rather seen this section based more on how young reptiles and birds act. Even young emus don’t act this way and they’re basically living muppets.

“Tyrannosaurus rex often lose 2/3rds of their original brood of 15 or so in the first year”

We have no T. rex nests, nor any hatchlings. This is a completely made up “fact”.

Doting dad

Again, no T. rex hatchlings, much less any association with any adult. Could be a doting dad, mom, both, or none. All options are on the table for this one.

Mostly speculation

T. rex the “very effective” swimmer

While it is likely that T. rex, like most dinosaurs, could swim, and it is true that the environments where we find T. rex would have had access to large bodies of water, none of this indicates that T. rex was at all a good swimmer. Lots of animals can swim, and Naish brings this up in this Prehistoric Planet: Uncovered segment. This segment shows horses and elephants swimming as examples, but again the question being answered here is not the question that should be asked.

It’s not: could T. rex swim?

It’s: was T. rex a good swimmer?

Naish points to the large feet of T. rex, but they aren’t abnormally large for a theropod of this size. They also were unlikely to have been webbed, which limits their ability to displace water when swimming. Frustratingly, there is no discussion of tail use in T. rex. The comparison goes straight to birds, which effectively have no tails. T. rex had a massive tail. Despite the tail being rounder in cross-section than something like a crocodile, the large surface area would still make this a more effective sculling organ than the dinosaur’s feet. Aside from the standard “birds are dinosaurs” comparison going on here, this approach is partially bolstered by “swim tracks” of dinosaurs that have been recorded in the fossil record. However, swim traces are controversial and not easily distinguished. Most recently, a re-analysis of sauropod swim tracks found them to more likely be the result of differential erosion of a time-averaged track site (Adams et al. 2025). Further compounding matters is that traces often counted as a swim tracks in the fossil record better fit the description of underwater punting (launching from one’s feet underwater). Hippos don’t swim and use punting as their primary means of locomotion in the water. Crocodylians and snapping turtles do swim, yet even they will regularly punt along the bottom of a pond or lake. Work by Farlow and colleagues (2018) does a great job of fleshing this out more. This does make sense when one considers the requirements of swimming. A swimming animal is buoyant and thus doesn’t touch the ground. If an animal is not touching the ground then it can’t make an impression that can be preserved. This is the same reason why we don’t have fossil impressions of flyers.

So, could T. rex swim? Probably. Was T. rex a good swimmer? Doubtful.

Then, we have the hatchlings that are somehow able to keep up with old dad here. Even if T. rex were a phenomenal swimmer, this efficiency would not translate between an adult and a youngster some 10,000 times smaller than it. These little guys should have been hitching a ride on dad’s back or have been several meters further away and even carried out to sea by the current.

T. rex family eats a dead protostegid

There were several sea turtles groups throughout the Cretaceous, including ancestors of our modern-day chelonioids, but protostegids appear to have gone extinct by the Maastrichtian and did not make it up to the K/Pg. That said, more samples could easily change this. Currently, the lack of data (or at least dearth of it) makes this scenario unlikely without this species being something else.

T. rex has the most powerful jaws in nature

This is just standard T. rex overhype. Deinosuchus, Sarcosuchus, Otodus megalodon, and Pliosaurus all reach or exceed bite force estimates for T. rex. Then again, maybe Attenborough meant most powerful jaws at this point in time. Honestly, this brief slip is minor compared to other parts of the program.

Hatchlings hold down baby turtles with their feet before tearing into them

Biomechanical data neither supports nor refutes this hunting style. There is some evidence to point to tyrannosaurs using violent flinging motions with their neck (Snively and Russell 2007) but this all based on adult animals. Younger animals may have done things differently here.

Reasonable inference…but still speculation

Mosasaurus eats a hatchling T. rex rather than mess with the large adult

This seems likely based on how extant predators choose their targets, but this entire scenario is still based on no data.

Scene 2: African pterosaurs

Baseless speculation

Tethydraco the caring parent

To date, we have no evidence of extensive parental care in any pterosaur. The current hypothesis is that pterosaur hatchlings were precocial and ready to fly almost from the start. Parental care could certainly still be present, but it was probably more limited that is shown here. Either way, we don’t even have evidence of eggs for Tethydraco, much less any statement about staying around to protect their brood.

Precocial Alcione elainus hatchlings take 5 years to grow up

This is closer to what we currently know about pterosaur hatchlings, though again we don’t have any specific evidence for this in Alcione. More frustrating is the choice to have Attenborough state that Alcione hatchlings take 5 years to reach somatic maturity. For reference, we have a single Alcione specimen and it’s a partial one with no skeletochronological information.

Mostly speculation

Reconstruction of several pterosaur species based on almost nothing

This episode features full reconstructions of the following pterosaurs. Parentheses indicate how much we really know about these species:

• • Tethydraco regalis (limb bones)
  • Phosphatodraco mauritanicus (cervical vertebrae)
  • Alcione elainus (partial skeleton with no skull)
  • Barbaridactylus grandis (isolated limb bones and a partial mandible)

As the show places a hard limit on a specific time frame of the Mesozoic, the species options are going to be limited. That’s understandable, but the lack of transparency here is still not excusable.

Alcione rookery

This is based on a site in Morocco that preserves over 200 specimens of pteranodontids and nyctosaurids (Longrich et al. 2018). A. elainus was found in this assemblage and thus makes sense for being in the show. There is no evidence of nesting or any type of rookery, though. That part appears to be made up. Similarly, while we have some solid evidence that pterosaurs as a group were largely precocial with limited parental care, the scenario described here is not backed by direct fossil evidence. All the statements about waiting time for wings to set and practice flight are equally speculative.

Reasonable inference…but still speculation

Barbaridactylus with a bony nyctosaurid crest

As mentioned above, we don’t have any skull material for B. grandis so this part has to come from comparisons with close relatives such as members of Nyctosaurus. As a nyctosaurid itself, B. grandis likely did have a similar head crest. Now, whether that crest was this set of bony spires remains a matter of debate. Large prongs like this don’t make much sense for animals that use them for display unless they are also using them for combat (i.e., deer antlers). The shape of the crest is not conducive to combat and looks much more like the supports for a fleshy crest. The current descent on this comes from work by Bennett (2003) who offered only a very brief comparison of B. grandis to more distant relatives like Tapejara imperator. I don’t find Bennett’s conclusion all that convincing and the associated paper doesn’t really focus on crest shape that much anyway. Nonetheless, I can accept this one as justifiable choice.

Scene 3: Zealandia and Sauropterygians

Baseless speculation

Reproductive mode and history of Taurangisaurus keyesi

Attenborough states that T. keyesi gives birth to a single baby once every two years. Whereas it’s likely that all plesiosaurs were viviparous, the size and number of young are unknown for all but one species (Polycotylus latippinus). As for birth rate, we have no way of knowing this at all. Similarly, the presentation of the caring mother here is based largely on the association of large body size for the newborn P. latippinus, and its correlation to some form of parental care.

Mostly speculation

Gastrolith eating in Taurangisaurus

The program shows a pod (also speculative) of T. keyesi stopping by the shallows to swallow some stones (gastroliths). Attenborough tells us that the plesiosaurs are using the stones for ballast. This is unlikely as research of gastroliths in extant animals (and estimated gastrolith concentrations in extinct ones) has found that they offer a slight affect to neutral buoyancy at best, but are mostly inconsequential compared to the buoyancy adjustments that can be made by adjusting lung volume and position (see Wings 2007 for review).

The stones that are swallowed in the show are also smooth, which is what occurs after gastroliths have been pulverizing food for awhile. Since the dramatization here is meant to reflect ballast function, though, that’s not as big of a deal. One thing worth keeping in mind is that stone swallowing is a common behaviour of several reptiles (now including sea turtles [Serafini et al. 2024]) and we don’t know why.

Scene 4: Junction of Atlantic Ocean and Tethys Sea

Reasonable inference…but still speculation

Mosasaurus hoffmani and cleaner fish

We see a large M. hoffmani lay on the bottom of the continental shelf allowing cleaner fish to pull out bits of flesh from the teeth. The little fish zip in and out of the mouth as they clean things away. This behaviour is seen in several extant animals today. “Cleaner stations” are common sites along continental shelves and several species of fish (including many sharks) will use these “stations” to get rid of ectoparasites. 

So, this is fine from a plausible point of view. We just don’t have any evidence for it in the fossil record. As for cleaning food from the teeth, this would have been incidental. Mosasaurs replaced their teeth regularly, which limits the need to clean stuck pieces of meat from the teeth. The main appeal of a “cleaner station” is to get rid of ectoparasites that are harassing the animal.

We also see the cleaner fish removing some stuck pieces of shed. This is also plausible even if mosasaurs moved away from the molting style of shedding that we see in extant squamates (which we don’t know, but is possible).

Again, the only real complaints here are that we don’t have any direct evidence for this and must rely on reasonable inferences.

Young upstart challenges the older adult to a fight

This has better direct support for it than the cleaner fish as we have several mosasaur fossils that show signs of violent interactions with conspecifics and other mosasaur species (see Bastiaans et al. 2020 for a review). The scene that is on display in the show is completely made up (i.e., not based on a fossil find) but the likelihood of such an interaction is viable.

The swimming in the M. hoffmani looks largely good. The only weird part comes in during the fight where the two are swimming together and it occasionally looks strange. I chalk this up to a difficulty in showing off the scale of these animals.

Scene 5: Coasts of North America

Baseless speculation

Psychedelic ammonites

Here we see a school of unnamed ammonite species in the Scaphitidae family rising from the depths in a mass mating event with males and females not just flashing different colours but incorporating bioluminescence into the mix.

This entire scene relies heavily on the known breadth of colour-changing abilities seen in extant cephalopods along with a handful of bioluminescent abilities found in some species. Cephalopod colour change is made possible through the use of their neuromuscularly controlled chromatophores. This anatomy allows for near instantaneous changes in colour and pattern. Such colour changing capacity is well documented in squid, octopodes, and cuttlefish. The one odd duck in the extant cephalopod mix is the chambered nautilus (a catch-all term for several species in Nautilus).

The phylogenetic relationship of ammonites places them between nautiloids and coleoids (squid, cuttlefish, and octopodes).  Phylogenetically ammonites are “more closely related” to coleoids, but they are still more basal than any coleoid. This leaves us in a bind. Nautiloids do not have neuromuscularly controlled chromatophores (at least, the modern one’s don’t), whereas all coleoids do. That makes neuromuscularly controlled chromatophores a synapomorphy for Coeloidea until otherwise determined.

To put it more bluntly: there is no evidence that ammonites could change colour.

Making matters ten times worse are the use of consciously-determined bioluminescence. This is accomplished via photocytes, which squeeze on photophores, releasing bioluminescent enzymes. Whereas chromatophores are pretty widely distributed among extant cephalopods, only a handful of extant squid have photocytes. So, the plausibility of ammonites utilizing these structures dramatically drops. 

Continuing to make matters we are shown these scaphitids rising up from the depths, indicating that they are using their photophores from deep down in the ocean. Bioluminescent aquatic animals are mostly found in the “midnight zone” (bathypelagic) of the ocean and deeper. So, aside from the current phylogenetic problem, we must once again point to nautiloids. Extant nautilus does live in deep water, but that depth stops around 700 meters. Much further below this level and the shells of nautiloids implode from the pressure. Biomechanical data on scaphitid shells indicates that they were far less capable of handling depth, maxing out around 100 meters (Hewitt 1996). So, having deep-sea dwelling ammonites is currently difficult to justify based on functional morphology, much less ammonites capable of rising through this massive water column daily or seasonally.

Lastly, we have the whole mating display, with coordinated light shows. This entire scene is completely fictional without a shred of hard data to support it.

Scene 6: Tuarangisaurus pod attack

Baseless speculation

Juveniles plays tag with Kaikaifilu hervei to save mom

In this scene we see a pod (same pod?) of T. keyesi attracting the attention of the large mosasaur, Kaikaifilu hervei. The mother is pregnant with her next child, and is followed by her two-year-old daughter. To keep her mother from being attacked by K. hervei, the daughter distracts the predator, giving time for her mom to escape and for the pod to mount a counterattack.

This scene plays out like something from a Disney film. Once again, the only basis for this interaction is the fact that both animals lived in the same area at the same time. We have no evidence for pod life, extended parental care, nor this level of altruism.

Final Sin Count: 21

References

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