General Misconceptions Relevant to Prehistoric Planet

Even in the modern day, when prehistoric knowledge and life in general is improved, some misconceptions and stereotypes started by popular culture remain, hence, despite mostly bringing up accurate, likely, or at least very reasonable information, some of those who have watched the show may erroneously think that the topics presented by Prehistoric Planet are wrong or have no precedence. This page is meant to clear up the various general misconceptions and stereotypical assumptions regarding prehistoric life.

It should be noted that this page is not for every misconception made by the general public. Specific misconceptions for specific creatures and places should be explained in their respective articles. Misconceptions that are too basic and can be too easily explained away will also not appear here. This page is also meant to help complement Prehistoric Planet's rules and regulations, with the misconceptions being set straight here serving as extra rules and standards that should be given consideration first before edits are made.

For actual errors, outdated information, and speculations shown and depicted on Prehistoric Planet, see the scientific errors and speculations page.

Behavioral Patterns

The concept of animal behavioral patterns is more than simply being "diurnal" or "nocturnal". It is more of a spectrum, with many variations in between being purely a day or night creature.

• Animals that are diurnal are primarily active during the day. They are monophasic, sleeping or otherwise assuming an inactive state once in a 24-hour cycle, during the night.
• Animals that are nocturnal are primarily active at night. They are also monophasic, resting during the day.
• Some animals are crepuscular, active during twilight hours. Some crepuscular creatures like rabbits, skunks, hyenas, and tigers, are sometimes erroneously classified as nocturnal.
  • Matutinal animals are only active before sunrise.
  • Vespertine (also known as vespertinal) animals are only active after sunset.
  • There is no special term for crepuscular animals that are both matutinal and vespertine, so calling such an animal "crepuscular" would suffice.
  • Some crepuscular animals can also be active during moonlight or an overcast (very cloudy) day.
• Cathemeral (also known as metaturnal) animals do not conform to any of the above standards. They are active at irregular intervals, and may be polyphasic, sleeping around 4 - 6 times throughout a 24-hour period. Some cathemeral creatures like fossas and lions are sometimes erroneously classified as either diurnal or nocturnal.

Behavioral patterns may change depending on the climate, conditions (the day may be too hot, the night may be too cold), presence of predators, availability of prey, niche partitioning, etc.

One way of judging an animal's behavioral pattern is by judging their eye size, sometimes specifically the scleral or sclerotic ring (a bony ring that supports the eye, usually seen in animals that live underwater, or animals that have non-spherical eyes).

• Tyrannosaurus rex has eyes that are 14 centimeters (5.5 inches) in diameter, providing it powerful binocular vision that can work in low-light conditions. However, in 2021, a comparison with the alvarezsaur Shuvuuia suggested that T. rex and Dromaeosaurus were diurnal. It is also possible that T. rex was neither fully diurnal or nocturnal, but cathemeral.
• The large sclerotic ring of Protoceratops indicates that it is nocturnal or cathemeral, while the proportionally larger eyes of Velociraptor suggest that it was even more adapted for nocturnality. These theories imply that the famous "Fighting Dinosaurs" fossil involving both animals preserves a duel that happened during twilight or in low-light conditions and events like a sandstorm (which is one possible cause of the animals being buried alive, the other theory being a dune collapse).
• Nemegtosaurus has medium-sized sclerotic rings, indicating that it is also cathemeral, which is not too surprising given how even large, modern-day animals from ungulates to elephants evolved to live a cathemeral lifestyle.
• Despite its small size (around less than 3 meters or 10 feet long), Phosphorosaurus possesses the largest eyes of any mosasaur in terms of proportion, giving it a binocular field of view of 35 degrees. This is unusually high for non-snake squamates, which typically exhibit a binocular field of view of 10 - 20 degrees, and is higher than those of other measured mosasaurs by at least 5 degrees. This grants it depth perception (which most hunters need) as well as great vision in low-light conditions, indicating that it either hunted in deep water, during the night, or both. The first segment of Oceans, set in the Hakobuchi Formation of early Maastrichtian Hokkaido, Japan, depicts Phosphorosaurus going after lanternfish (which are known within the area), at night serving as justification for its large, powerful eyes, which help it discern the right prey to pick amidst their deliberately-confusing light signals.
• Pterosaurs like Tupuxuara are mostly seen as diurnal animals based on their sclerotic rings, but members of the anurognathidae family resemble bats and nightjars, with their looks suggesting a similar crepuscular or nocturnal lifestyle, given how they have teeth suited for insects and/or fish as well as large eyes for low-light conditions.
• Not all dinosaurs with large eyes are specialized for low-light conditions. For example, while Leaellynasaura of Early Cretaceous Australia may have faced months of winter darkness, the large eyes of one specimen are interpreted as juvenile features (since juveniles have proportionally larger features compared to adults) rather than low-light adaptations.

The "Cheek" Anatomy of Herbivorous Dinosaurs

On Prehistoric Planet, Pachycephalosaurus and its relative Prenocephale are depicted without cheeks, in sharp contrast with their marginocephalian relatives, ceratopsians like Triceratops and Pachyrhinosaurus, which are portrayed with cheeks.

Basal ornithischians like Pachycephalosaurus has primitive teeth, a lizard-like chewing style, and lizard-like "lips" instead of "cheeks"

According to the works of paleontologist and anatomist Dr. Ali Nabavizadeh, basal ornithischians (heterodontosaurids, basal thyreophorans, basal ornithopods, basal ceratopsians, and pachycephalosaurs) had coronoid processes (the blade-like protuberances on either side of the mandible) that were short, not tall, similar to those of lepidosaurs (e.g. lizards and tuataras). Furthermore, these basal ornithischians also had lepidosaur-like buccal emarginations (the raised ridges that run along the outer side of the teeth next to the cheeks, defining the cusp tips and guiding chewing forces), and thus had lizard-like "lips", with no cheek-like flaps of skin connecting the upper and lower jaws. Their labial dentary ridges (bone ridges lateral to the teeth) are also as relatively prominent as those of spiny-tailed lizards and tuataras, being only thin, rounded, rostrally (near the front) elongated projections. Their retroarticular processes (the bony walls that form the back of the temporomandibular joints, which connect the mandible to the skull) are noticeably long, and their pterygoid bones (which form part of the palate) have large flanges, indicating that their medial pterygoid muscles (important for mastication, the act of chewing) are hypertrophied, heavily developed compared to those of ceratopsids, stegosaurs, and ankylosaurs, which have retroarticular processes that are small or almost nonexistent.

As more derived ornithischians, ceratopsians like Triceratops had more advanced dental batteries, jaw muscles for more complex mastication, and buccal flaps to cover these muscles like true cheeks

By contrast, the more derived ornithischians tended to have more prominent labial dentary ridges which were shelf like, with smooth bony textures on the dorsal rims, resembling the muscle attachments of animals like dicynodonts, with ceratopsian jaw adductor muscles having a more rostral attachment than those of hadrosaurs. The foramina (pits for blood vessels) in the labial dentary and maxillary ridges of ceratopsians and ankylosaurs suggest that their jaw adductor muscles required increased vascularization (formation of blood vessels), and their presence medial to the coronoid process suggest these foramina are not for tactile nerve endings because they are not exposed externally, supporting the idea that they had cheeks to cover their jaw muscles. By comparison, basal ornithischians are like lepidosaurs in that their foramina is concentrated rostrally as opposed to labially along the caudal (hind) margin of the tooth row. Ceratopsians and iguanodontians (including hadrosaurs) also have tall, columnar coronoid processes, and the configuration of their buccal emarginations allow large groups of jaw muscles to fit within reasonable margins while the mouth is closed.

Like ceratopsians, hadrosaurs like Edmontosaurus had dental batteries and likely also jaw adductor muscles covered by flaps of skin that resemble - but are not analogous to - mammalian cheeks

Regardless of whether they did have cheeks or not, current understanding has it that dinosaur cheeks are not like those of mammals, since, contrary to popular belief, dinosaurs did not need cheeks to hold food, for they do not chew from side to side like mammals. Although at least some dinosaurs had skin covering the adductor muscles extending across their upper and lower jaws (some birds like condors do indeed have flaps of skin stretching across the sides of their mouths, while the nodosaurid Panoplosaurus of the Campanian Dinosaur Park Formation in Canada shows evidence of buccal flaps), no sauropsid (what is understood to be "reptiles", including avian dinosaurs) possesses cheeks or lips that are analogous to the more complex facial muscle anatomy of mammals.

Inspired by the studies of Dr. Ali Nabavizadeh, Dr. Darren Naish, lead consultant of Prehistoric Planet, designed Prehistoric Planet's pachycephalosaurs to reflect these findings. With their simpler, more primitive, lizard-like teeth, pachycephalosaurs chewed food more like a lizard as opposed to the complex manner in which ceratopsians and ornithopods (at least, the more derived ones) chewed. For these reasons, Prehistoric Planet portrays pachycephalosaurs without cheeks, their jaws lined with large scales resembling the "lips" of lizards.

The Classification of Birds, Dinosaurs, and Reptiles in General

To this day, the concept of Linnaean Taxonomy persists. In truth, this means of classifying biological organisms is rendered outdated and obsolete by cladistics (derived from kládos, the Ancient Greek term for "branch"), a standard that first appeared in 1901 and eventually became adopted by the scientific community as the proper, technical way of classifying living beings.

The way cladistics works is that animals are grouped by their most common ancestor. If an animal is a part of a group (known as a "clade", hence the name of this standard), it would not separate from that group no matter how much it evolves, it would always remain a member of the group it came from (in short, descendants of a clade will always be members of that clade no matter what). Clades rely on "monophyly", that is, the group must have the last common ancestor of all its members, and the group must contain all the descendants of that last common ancestor without exception. Clades cannot be considered valid if they are "paraphyletic", that is, they do not contain all of the descendants of the last common ancestor, either because of perceived distinctions or the status of an animal as an extant (still-living) or extinct creature, with none of these being legitimate factors in cladistics. Clades are not to be confused with grades, more generic terms, groups that are paraphyletic because they are based on similar physical characteristics and not evolutionary branches (which are what truly and technically dictates the relationships between animals). In that regard, here are statements that are outright correct.

• Birds are descendants of dinosaurs, and therefore are dinosaurs. This is not a fringe theory or a matter of debate anymore. It is just as true as saying humans are a type of primate.
  • Birds are specifically a type of paravian, paravians are specifically a type of maniraptoran theropod, theropods are a specific type of saurischian dinosaur, and there are many other subgroups in between these layers, all of which further reinforce the point that birds are deeply nested in the Dinosauria clade. Because they are maniraptoran theropods, technically:
    • All birds (not just the chicken, or eagle, or cassowary, or peacock) are more closely related to Velociraptor than Velociraptor is to Therizinosaurus (which is a non-paravian maniraptoran).
    • All birds are more closely related to Therizinosaurus than Therizinosaurus is to T. rex (which is a non-maniraptoran theropod).
    • All birds are more closely related to T. rex than T. rex is to sauropods like Alamosaurus (sauropods are saurischians, like theropods).
    • All birds are more closely related to sauropods like Alamosaurus than sauropods are to ornithischians like Triceratops and Edmontosaurus.
    • Because of this, for one to say that birds are not dinosaurs, one must also believe that the other types of dinosaur are not dinosaurs, because some of them are even less-related to each other than the birds are to them. If this is to be believed, then that means there is no such thing as a dinosaur because the group is invalid due to being made up of unrelated animals. However, a dozen synapomorphies (characteristics) in their skeletal anatomy (among these, skull and pelvis features) validate the fact that these animals all came from a common ancestor, hence, Dinosauria is a valid group.
  • It is incorrect to say "dinosaurs are a type of bird" or "dinosaurs are birds". It is synonymous to saying that dinosaurs (the group) came from birds (the subgroup which belongs within the group).
  • Calling a bird an "avian dinosaur" is technically correct (hence, this term is frequently used throughout the wiki to make it clear what birds are). Calling other dinosaurs "non-avian dinosaurs" helps differentiate them, but this term is technically incorrect, as this would mean saying that avian dinosaurs (birds) are a type of non-avian dinosaur.
    • Expanding on this, saying "dinosaurs are closely related to birds" is only correct if "dinosaur" in that statement refers to other dinosaur groups that do not contain birds, and would otherwise cause confusion or spread the wrong idea that birds are a parallel branch of life that is still separate from them. Stating "birds are types of dinosaurs and not simply close relatives" is a better way to present and reinforce the correct view.
“ In the air, we've got this fantastic diversity of flying reptiles we call "pterosaurs". These things are often referred to as "flying dinosaurs", but they're not. ”

― Dr. Mark Witton, Palaeoartist and Palaeontologist
• Pterosaurs are not dinosaurs, much less birds. There is the common misconception that pterosaurs are "flying dinosaurs", which is a term that can only technically be used for birds that are still capable of flight.
  • The absence of certain features, most notably open hip sockets (where the thigh bones attached to the pelvis) that are found only in dinosaurs, separate pterosaurs from the dinosauromorphs (dinosaurs and their close, non-dinosaur relatives).
  • Nevertheless, pterosaurs and dinosaurs are both members of a group called "Ornithodira" within the "Avemetatarsalia" clade.
“ Mosasaurs were seagoing lizards. Think of a giant, swimming, whale-sized Komodo Dragon. Tapered snout, rough skin, four fins instead of normal limbs, and a long tail that would look a lot like a shark tail, but upside down. That's basically a mosasaur. ”

― Dr. Michael Habib, University of California
• Mosasaurs are descendants of lizards, and therefore are lizards. Mosasaurs are part of the "Squamata" order, which contains lizards and snakes. Even so, given the limbs present in the earliest mosasauroids like Dallasaurus (in a time when snakes already lost theirs), it is unlikely that they came from Ophidia (snakes), with a 2022 study concluding that attempts to classify mosasaurs as being closer to snakes than lizards are based on vague or misinterpreted pieces of evidence, and they are more likely closer to varanoids (which contains the family of varanids, monitor lizards), but apparently not too close.
  • That being said, the generic term "lizards" (not to be confused with the technical order Squamata) is itself paraphyletic, because some of the so-called "lizards" are more closely related to snakes than they are to other lizards. This is not the same case as avian dinosaurs (birds), since "avialae" is a legit grouping of animals that are closely related to each other.
  • Mosasaurs are believed to have forked tongues, much like lizards and snakes, which collect chemical particles from the environment with their tongues and insert them into the vomeronasal organ (also known as Jacobson's organ) by their palate. This feature still works very well for sea snakes, so it would also work just fine for mosasaurs. While usually depicted as long, slim and deeply-forked like those of snakes, Prehistoric Planet instead modeled their tongues after the shorter, thicker, and less-mobile tongues of anguimorph lizards, since mosasaurs are believed to be part of the anguimorph group themselves. However, while this means that mosasaurs are in the same group as varanids (monitor lizards), they do not seem that close to them, and mosasaurs may possibly not be anguimorphs at all. It is better to say that mosasaurs resemble Komodo Dragons with the features of orcas and sharks rather than outright state that mosasaurs are closely related to Komodo Dragons.
  • Squamates, along with the Rhynchocephalia order (which has only one living member, the tuatara), are members of the Lepidosauria superorder, which is, in turn, part of the Lepidosauromorpha clade, which contains other extinct species. Lepidosauromorphs and the distinct clade of Archosauria are part of the Sauria clade within Reptilia. This means that squamates are not archosaurs, and mosasaurs are only related to dinosaurs in the sense that both are reptiles within the Sauria clade, but nothing more than that. Squamates (and therefore, mosasaurs) are also distinct from the sauropterygians, a fully-extinct superorder of reptiles that contains the ichthyosaurs, nothosaurs, and plesiosaurs.
• Mammals did not come from reptiles. Both reptiles and mammals came from the Amniota clade, but their ancestors have long split up before reptiles and mammals existed. Hence, reptiles and mammals are simply parallel branches, and any similarities between them are either inherited and derived from their last common amniote ancestor, or the result of convergent evolution.
  • One group of amniotes, "Sauropsida", refers to a wide range of animals, some of which evolved into reptiles. Reptiles descended from sauropsids, and therefore are sauropsids.
  • Another group of amniotes, "Synapsida", refers to a wide range of animals, some of which evolved into mammals. Mammals descended from synapsids, and therefore are synapsids.
    • Because Dimetrodon is a synapsid, it did not come from reptiles. Hence, calling it or any of its relatives "mammal-like reptile" is wrong, and neither is it a direct ancestor of mammals. Instead, the proper terms for it would be "stem mammal", "protomammal", or "paramammal".
  • The "Amniota" clade is itself part of a group called "Reptiliomorpha", which is not to be confused with the actual reptile class ("Reptilia") within Sauropsida.
• All tetrapods are lobe-finned fish. The concept of "fish" for most simply includes certain water-living vertebrates that do not fit the definition of amphibian, reptile (including birds), or mammal. Such a term is a grade, a paraphyletic grouping that is not a proper biological clade. The superclass known as "Tetrapoda" (a misnomer, because some members, like snakes, caecilians, sirens, and whales, do not have four feet, or even remnants of their former limbs) consists of all vertebrates that evolved from "Sarcopterygii" (lobe-finned fish), a type of bony fish ("Osteichthyes"). In essence, amphibians, reptiles, and mammals are all bony fish, provided that one views and defines fish in the cladistic sense as opposed to vernacular, as opposed to informal understanding.

This cladogram by Dr. Darren Naish, focused on maniraptoran theropods, shows that birds are deeply nested in the Dinosauria clade.

This cladogram by Dr. Darren Naish is about squamates. Mosasaurs are believed to be within the anguimorph clade, and therefore deeply nested in the Squamata order.

Prehistoric Animal Size Factors

Main: How Did Dinosaurs Get So Big?

Main: How Did Dinosaurs Get So Big?

“ There have been a lot of strange ideas about why dinosaurs could have gotten so big. One of my favorites was that gravity has changed through time, and maybe the gravity of the Earth was lower in the past which have meant that the animals got correspondingly larger. It's an interesting idea, but an idea that's very definitely nonsense, the Earth's gravity has not changed that much in the last few hundred million years. ”

― Professor Paul Barrett, Natural History Museum

Several outdated ideas have been made in regards to dinosaur size. The section for the Uncovered segment, "How Did Dinosaurs Get So Big?", tackles this topic, and even includes points that are not brought up in the segment, like misconceptions regarding the amount of oxygen during the Mesozoic Era.

Outdated or disproven reasons include - but are not limited to:

• Lower gravity. Throughout Earth's history, gravity did not undergo noticeable changes for life to adapt to.
• Higher oxygen levels. Some studies suggested that oxygen levels during the time of the dinosaurs were around 30% compared to the modern day's 21%. While the early dinosaurs are believed to have been boosted by oxygen levels increasing compared to previous time periods, later studies estimate that oxygen levels in the past 220 million years were only around 10 - 19%, lower than oxygen levels today, and, regardless, would not have helped dinosaurs reach large sizes the same way high oxygen levels during the Carboniferous Period (above 21%) allowed insects to reach larger sizes (since, without these higher oxygen levels, insects were limited in body size due to how their respiratory system diffuses oxygen).

Legitimate, accepted reasons include - but are not limited to:

• Quick growth, a trait usually seen in endothermic animals, with extended growth allowing for greater sizes.
• Bones that are strong, yet comparatively light for their size due to a hollow, pneumatized, or Styrofoam-like construction.
• A system of air sacs forming efficient respiratory systems that extract oxygen both during inhalation and exhalation, as can be seen in birds today.
• An upright posture to help support the body's weight more firmly.
• Evolutionary pressures due to the presence and adaptations of prey, predators, and competitors.

These reasons can also be considered true for other animals during the time of the dinosaurs, among them, crocodyliforms like Sarcosuchus and Deinosuchus, as well as pterosaurs. Fully aquatic animals like mosasaurs and plesiosaurs evolved for some of the same reasons like efficient metabolisms and quick growth, though, much like giant fish and whales today, it helps that most of their mass is supported by the waters they swim in.

Pterosaur Flight

Nyctosaurus takes off using the quadrupedal launch technique.

There is the belief that pterosaurs are either flightless, or were only able to fly due to the high amount of oxygen in prehistoric times, and thus would not have been able to maintain lift or have the energy to fly in modern times.

This issue stems from at least four misconceptions, outdated views from a time when all pterosaurs were viewed as analogous to seabirds, ideas that ought to be dispelled today, mostly with the help of studies by three of the experts who worked on Prehistoric Planet, Dr. Darren Naish (who served as the show's lead consultant), Dr. Mark Witton, and Dr. Michael Habib.

• Pterosaurs are cold-blooded. Modern studies indicate that pterosaurs are actually endothermic, in essence, highly-active "warm-blooded" animals.
• Histological (microscopic anatomy) analysis and ultraviolet examination has proven that pterosaurs are covered in pycnofibers (dense fibers), feather-like structures that resemble mammalian hair due to convergent evolution. This indicated that pterosaurs needed to be able to generate enough heat with their own bodies to keep their temperature and metabolism stable.
• Pterosaurs are limited by the same constraints as avian dinosaurs (birds), and thus do not possess the energy to fly, at least, not efficiently. In truth, while there are some similarities, pterosaurs work differently from birds.
• Birds only have two legs which they use to jump off the ground, with some even needing to run in order to take off. This limited the size of birds, hence, Pelagornis, Argentavis, Haast's Eagles, Andean Condors, and Kori Bustards represent the maximum size a bird can reach while still having the capability of flight. Any heavier than that (e.g. ostriches, emus, terror birds), and birds would have needed to completely sacrifice their flight capabilities.
• Unlike birds, pterosaurs were able to walk on their wings. Since these wings needed to support their mass, they were built with sturdy bones and powerful muscles. These adaptations allow the pterosaurs to employ what is called the "quadrupedal launch" technique, as suggested by Dr. Mark Witton and Dr. Michael Habib. Strong, muscular forelimbs and pectoral muscles allowed pterosaurs to leap forward with tremendous force, catapulting their lightweight bodies into the air, before quickly spreading their wings to achieve lift.
• Pterosaurs are too heavy to fly. Pterosaurs were actually lightweight for their size.
• Pterosaurs generally have hollow bones. Their massive heads are no different from those of toucans or pelicans, possessing massive but hollow beaks that were light yet sturdy enough to capture prey. Their bodies are also heavily pneumatized, full of air sacs to lessen their overall mass. One exception is Hatzegopteryx, which has bones with a spongy core resembling Styrofoam. While it was still light enough to fly, its spongy bones gave it increased toughness. Animals having hollow bones are also not necessarily fragile and weak, they are still structurally sound and reasonably durable.
• The largest pterosaurs ever discovered only weigh around around 200 - 250 kilograms (441 - 550 pounds). A lot of their mass is taken up by flight muscles, which can weigh a total of 50 kilograms (110 pounds), making up 20 - 25% of the total body mass of the largest azhdarchids.
• Coupled with their more efficient means of getting off the ground compared to birds, pterosaurs were not restricted to the same body size and form limitation as birds. This allowed for larger sizes, which allowed for more flight muscles, which permitted stronger flight capabilities. They would have overall had more energy to overcome the constraints that birds cannot.
• If they were too heavy to fly, the wings of azhdarchids (which first appeared 108 million years ago) should have long become vestigial, and some think this could be the case. But this misconception stems from views of the animals with their wings folded so they can walk on the ground, giving off the illusion that their wings are small. Azhdarchids have wings that span around 9 - 12 meters (30 - 40 feet) when unfolded, and if these wings were vestigial, azhdarchids would not have needed flight muscles that take up a quarter of their body weight.
• The higher oxygen content of the Mesozoic Era is what kept the pterosaurs aloft, and allowed them to grow huge in the first place and have the energy to overcome constraints that flying animals cannot overcome today. As is the case for large dinosaurs, pterosaurs did not rely on the Earth's conditions to permit them to grow or have enough energy to keep their large bodies aloft, they simply evolved more efficient solutions that can work even with the limitations imposed by Earth's conditions.
• As explained in the Prehistoric Animal Size Factors section above, oxygen levels in the past 220 million years were only around 10 - 19%, lower than it is today at 21%, though the lower amount of oxygen is not significant enough to make a difference, as pterosaurs do not have a limited respiratory system like insects.
• More oxygen and a thinner atmosphere would not have been sufficient to carry a 250-kilogram (550-pound) animal off of the ground. For that to happen, the animal must be able to take off and maintain lift on its own. Although some pterosaurs may have been capable of soaring, they were also capable of relying on nothing but their own power.
• Dr. Darren Naish clarified that pterosaurs would have been able to fly just fine even in environments like those of the modern day. The adaptations they used to conquer the skies are not unique in the history of life, they were simply the ones who evolved these solutions to the extreme.

Overall, while they share similarities with birds, pterosaurs have evolved for flight with arguably more efficient adaptations, and thus should not be judged by the same standards as birds, nor should their flight capabilities be considered invalid simply because of the supposed notion of different atmospheric conditions between prehistoric times and the modern day. While some studies suggest that large pterosaurs did not soar at all, and only flew short distances, other studies, like those of Dr. Michael Habib, suggest that such light weight and powerful muscles allow animals like Quetzalcoatlus to fly at a maximum height of 4.6 kilometers (2.86 miles), and, at a speed of approximately 130 kilometers (80 miles) per hour, cover around 13,000 - 19,000 kilometers (8,000 - 12,000 miles), enough to traverse oceans and visit other continents in 7 - 10 days.

The misconception of pterosaur flight extends even to their juveniles, stemming from the fact that a majority of modern-day flying vertebrates are incapable of flight early on in life. Most birds, depending on the species, must be around 10 days to 12 weeks old before being capable of flight. There are, however, exceptions, like megapodes and other galliform birds, which are capable of flight in a few days, or even on the very day they hatch. In a 2021 study by Dr. Darren Naish, Dr. Mark Witton, and Dr. Elizabeth Martin‑Silverstone (all three being involved in the making of Prehistoric Planet), pterosaurs are superprecocial, capable of extreme locomotor movements (including flight) shortly after hatching. By wing area to mass ratio, juvenile pterosaurs can out-glide living volant animals, and their wings are more suited for active, sustained flight as opposed to short-distance gliding. Additionally, the humeri (upper arm bones) of juvenile pterosaurs are also thick and robust in proportion to their length, allowing them to withstand great stress and further supporting the idea that they engaged in active flapping early on.

Not all pterosaurs flew the same way. In 2024, two azhdarchid pterosaurs from the Muwaqqar Formation in the highlands of Jordan were studied. One is Arambourgiania (named after Camille Arambourg, a French paleontologist), one of the tallest azhdarchids, now confirmed to have a wingspan of 10 meters (33 feet) based on a humerus (forearm bone) comparable to that of Quetzalcoatlus northropi. The other is the newly discovered Inabtanin (Grape Dragon), a pterosaur half its size (matching the size of Phosphatodraco), with a 5-meter (16-foot) wingspan. The insides of Inabtanin's flight bones had a crisscrossed arrangement of struts, similar to those of birds that rely on flapping to fly. On the other hand, Arambourgiania's humerus was filled with a helical series of ridges like those of vultures, which possess these spiral ridges to resist the torsional (twisting) forces of soaring flight. While pterosaurs were likely able to adapt other flying styles when needed, this is taken as evidence that pterosaurs started out reliant on flapping flight, while others would evolve adaptations for soaring flight to suit their needs. In the case of Arambourgiania, soaring flight would allow it to take advantage of thermals (convection updrafts) from the open ocean to remain airborne, allowing it to fly efficiently over its chosen habitat, which forms a coast by the Tethys Ocean.

Quetzalcoatlus takes off using the quadrupedal launch technique

Hatzegopteryx takes off using the quadrupedal launch technique

The Hatzegopteryxes leave the Liburnia Formation to hunt elsewhere

Thermoregulation

The concept of thermoregulation being clearly defined as either "cold-blooded" or "warm-blooded" is an outdated one. In truth, just like animal activity and sleep cycles, animal temperature maintenance is more of a spectrum with many categories that have boundaries that are not clearly defined.

• Animals that are ectothermic (Outside Heat) are reliant on the heat of their surroundings to maintain favorable body temperature and metabolism. This is not to be confused with "exothermy", which, in the context of physics, is a thermodynamic process where something releases energy to its surroundings (one example of this is an explosion, which releases intense amounts of heat, light, and sound).
• Animals that are endothermic (Inside Heat) are able to maintain their body heat with bodily functions rather than having to rely on the temperature of their environment. This is not to be confused with an identically-named thermodynamic process in the context of physics (endothermy) where something absorbs energy from its surroundings (examples of these include evaporation, sublimation, and thermal decomposition like burning).
  • Endotherms are able to survive changes in environmental conditions, live in colder climates, fight off infection by raising their body temperature, and be overall more energetic. This comes at a price; sustaining an active metabolism costs a lot of energy, hence, endotherms require more food than their ectothermic counterparts, and need to eat more frequently because their bodies process their meals more quickly.
  • Facultative endothermy involves an ectothermic animal raising their body temperature via vibrations (movement, shivering, exercise), though this only works within a certain threshold, and is not on par with proper endothermy.
  • Some organisms rely on regional endothermy, heating up only certain parts of their body with muscle activity (while the rest remain cooler).
• Animals that are mesothermic (Intermediate Heat) have thermoregulation and metabolism is better than ectotherms, but not as good as proper endotherms.
• Animals that are poikilothermic (Varied Heat) have internal temperature that fluctuates depending on a number of factors.
• Animals that are homeothermic (Similar Heat) maintain a constant, stable body temperature regardless of external influence.
• Animals that are gigantothermic (Giant Heat) maintain a stable body temperature with their great sizes, as their surface area is proportionally lesser than their overall volume, which means that they absorb heat quicker and lose heat slower than smaller animals. Animals that rely on gigantothermy are usually ectotherms.

Animals can fit more than one category, showing the different ways they evolved to adapt to their specific niches, the conditions of their habitat, their feeding lifestyle, etc. These are among the few examples that can showcase this idea:

• Most - but not all - fish and reptiles are ectothermic poikilotherms.
  • Larger fish, like whale sharks, are gigantothermic poikilotherms, relying on their massive bodies to stabilize their temperature and metabolism.
  • Large, macropredatory fish like lamnid sharks (e.g. great white shark, Otodus megalodon, etc) and Xiphactinus are endothermic or mesothermic poikilotherms, able to use their better metabolism for short bursts of speed, giving them an advantage in ambush and pursuit while hunting. They are, at the very least, capable of regional endothermy.
• Avian dinosaurs (birds) and mammals are endothermic homeotherms, maintaining a constant body temperature with their bodily functions.
  • Certain species of pythons, tegu lizards, and other reptiles are normally ectothermic, but briefly become endothermic during the reproductive season.
• Non-avian dinosaurs, pterosaurs, mosasaurs, and sauropterygians (ichthyosaurs and plesiosaurs) are endothermic or mesothermic homeotherms, and the degree of this can vary depending on species.
  • Smaller, feathered theropods are likely closer to birds in terms of thermoregulation, while larger animals would have likely had a high body temperature due to gigantothermy.
  • As with the large, macropredatory fish, large predatory theropods relied on their "warm-bloodedness" to be more effective predators.
    • The largest confirmed feathered animal is Yutyrannus (Feathered Tyrant), a proceratosaurid theropod that is 9 meters (30 feet) long, 1.4 metric tons (1.54 short tons) in body mass, and covered in filamentous feathers around 20 centimeters (8 inches) long. This not only shows that Yutyrannus was likely endothermic, it also implies that, 125 million years ago, northeast China was likely a temperate region positioned at a high latitude, an idea supported by oxygen isotopes in the Yixian Formation (the place where Yutyrannus is discovered) indicating average annual temperatures of 10 degrees Celsius (50 degrees Fahrenheit), and therefore cold winters.
    • A study in 1999 suggests that Giganotosaurus is a mesothermic homeotherm, capable of growing rapidly due to its metabolism. The idea is that this large theropod, weighing around 8 metric tons (8.8 short tons), had a metabolism comparable to that of a mammalian carnivore weighing a single metric ton (1.1 short tons).
    • T. rex and other large tyrannosaurs like Tarbosaurus may have had feathers in their juvenile stage, eventually losing almost all of their integument (perhaps except faint, hair-like remnants) upon reaching adulthood, likely because, by that point, their bodily functions are already efficient enough to warm them up without the need for feathers. The high growth rate of T. rex is also more like that of an endothermic animal, and a 2022 study, basing off of spectroscopic analysis of lipoxidation signals (byproducts of oxidative phosphorylation, correlating with metabolic rates), suggests that large dinosaurs were not gigantotherms, but true endotherms, with metabolism almost on par with those of modern birds. That study also implies that endothermy was an ancestral trait to ornithodirans (the clade that includes both dinosaurs and pterosaurs). These studies do not completely invalidate the idea that T. rex and other dinosaurs are gigantothermic mesotherms, however, it simply suggests that they may be outright endothermic.
    • While not predatory, Deinocheirus and Therizinosaurus are massive theropods. They are two of the largest non-sauropod herbivores in the Nemegt Formation of Mongolia, a rich, humid environment with large river channels, tidal flats, and forests (though periods of drought occasionally gave rise to deserts and arid badlands in the area). It has been argued that, because of their massive sizes and metabolisms, they were likely mesothermic or endothermic gigantotherms, which means that feathery coats would have ended up overheating them, so they would have only had a few feathers on them (as evidence of a pygostyle, a tail fan, on Deinocheirus, proves that it does have feathers). According to Dr. Darren Naish, the environment Deinocheirus and Therizinosaurus lived in is understood to be cool, and dinosaurs may have been better at temperature control compared to big mammals, thus serving as somewhat of a justification for the thick coat of feathers seen on Prehistoric Planet's depictions of Deinocheirus and Therizinosaurus.
  • Dinosaurs may have originated from a "warm-blooded" ancestor, but some ornithischians reverted to ectothermy. One example may be Stegosaurus, which relied on gigantothermy and its dorsal plates to absorb and lose heat, allowing it to maintain a stable body temperature.
  • Homeothermy in ichthyosaurs and plesiosaurs is supported by the discovery of subdermal fat that acts like blubber (and in the case of ichthyosaurs, actual blubber), fit for animals that must maintain an active metabolism and lifestyle.
  • The idea that non-avian dinosaurs died due to being "cold-blooded" is outdated since it has been established they were more on the "warm-blooded" side of the spectrum. Ironically, the "warm-blooded" nature of the dinosaurs, pterosaurs, plesiosaurs, and mosasaurs became a factor in their extinction. Every type of lifeform on Earth (even the ones that survived) got vastly affected by the cataclysmic state of Earth following the "Chicxulub Impact" (named after a town close to the crater left by the asteroid that landed in the Yucatán Peninsula), but some organism suffered even more than others; large ectothermic species like sea turtles and crocodiles could subsist on less and survive on an overall lower quality of existence, but endotherms cannot simply undergo brumation (the reptile equivalent of hibernation) or otherwise maintain a low metabolic state due to the higher and more constant biological demands of their more active nature, hence, amongst endotherms and mesotherms, almost nothing with a body mass greater than 25 kilograms (55 pounds) was able to survive the harsh times that followed the asteroid strike, with other factors allowing for exceptions very few and far between.

References

General

Dr. Ali Nabivazadeh

Dr. Darren Naish

Dr. Mark Witton

Dr. Mark Witton and Dr. Darren Naish

Dr. Michael Habib

Dr. Michael Habib and Dr. Mark Witton

Dr. Thomas Holtz

Prehistoric Planet