Pterosaurs of the Jurassic

The flying reptiles known as pterosaurs emerged during the Triassic Period. Pterosaur origins are murky and best discussed elsewhere. By the beginning of the Jurassic Period, pterosaurs began to diversify and radiate. Pterosaur radiated exploded like the Big Bang during the Late Jurassic; at that time, dozens upon dozens of new genera show up in the fossil record. For this reason the Late Jurassic has been considered by many the 'heyday' of the pterosaurs. For most of the Jurassic Period, the pterosaurs were short-skulled, long-tailed rhamphorhynchids. In the Late Jurassic, however, long-skulled, short-tailed pterosaurs known informally as pterodactyloids (or pterodactyls, depending on who you talk to) emerged. It's believed that these were off-shoots of the rhamphorhynchids. It wasn't long before pterodactyloids began to overtake the rhamphorhynchids, and the Late Jurassic wound up being the twilight of the short-skulled, long-tailed pterosaurs. The pterodactyloids would continue into the Cretaceous Period without the 'baggage' of their predecessors. 

~ The Early Jurassic ~

Dimorphodon portrayed with a brightly-colored beak

Dimorphodon is the first early Jurassic pterosaur we meet on our journey. It lived between 195-190 million years ago during the Simenurian and Pliensbachian stages of the Early Jurassic. This pterosaur had a five-foot wingspan and dominated the flurry of wooded islands that was prehistoric England. This puffin-like rhamphorhynchid was 3’3” long head-to-tail with its head measuring eight inches. The head was large and heavy with a deep, narrow snout. The skull was built of bony struts rather than large slabs, and it had lots of wide openings – fenestrae – to increase the lightweight. Studies of its hips, legs, and feet indicate that it may have stood upright and balanced on its toes while walking, just like modern birds. It had five toes on each foot, and all had claws except the fifth digit (or ‘little toe’). This little toe angled sideways and would’ve improved balance when Dimorphodon was standing or running. This stance makes Dimorphodon unusual, as most pterosaurs had weak legs that splayed out to the sides and could probably only shuffle with a sprawling gait. Dimorphodon’s tail was long and stiff, and its three-fingered hands were strong and curved with sharp claws designed for climbing rocks or trees. Its beak was tall from top-to-bottom but narrow side-to-side. Scientists speculate it may have been brightly colored in life and used in visual displays; like modern puffins and hornbills, it may have used vibrant colors to ‘stake out’ its territory or attract mates and intimidate rivals. 

Dimorphodon portrayed as a fish-eater; note the Dimorphodon
clinging to the rock-face in the background

Dimorphodon had two types of teeth in its jaws – hence the meaning of its name, ‘two-form tooth’ – and these consisted of four pairs of large, peg-like teeth at the front of both upper and lower jaws, followed by thirty to forty smaller teeth behind. Dimorphodon’s diet has been debated down the decades, which isn’t surprising given its two-formed teeth morphology. Paleontologists first believed it was insectivorous, but consensus then swung to a pescivorous (fish-eating) diet. Its jaw structure had an advanced jaw musculature specialized for a ‘snap and hold’ feeding method: the jaws could close very fast, but they lacked enough force for the teeth to penetrate tough flesh. This, coupled with its short and high skull and longer, pointed front teeth lend weight to the original identification of an insectivorous lifestyle (though it may have occasionally eaten small vertebrates or carrion). More recently it’s been argued that Dimorphodon was a specialized carnivore, being too large for an insectivorous diet and therefore subsisting off small lizards and mammals. Its weak jaw musculature, however, implies that it would’ve been forced to hunt smaller creatures. Given its ecosystem of wooded islands, such a lifestyle wouldn’t be surprising, as islands are often host to smaller organisms than are found on the mainland. Whether Dimorphodon hunted ‘on the wing’ while in flight or while walking around is debated, as well. 

An artistic rendering of Campylognathoides 

Now we shoot forward to the Toarcian Stage of the Early Jurassic around 182 million years ago. Campylognathoides remains have been found in both Europe and India (southern Laurasia). This was a gigantic pterosaur for its time, with a wingspan of five feet and eight inches. It was originally named Campylognathus but was redescribed and renamed later. Campylognathoides had a slight upward hook to the front of the jaw and had a pointed snout. Its eyes were large, indicating acute eyesight and perhaps even a nocturnal or diurnal (dawn or dusk) lifestyle. Its teeth were conical and recurved, ideal for delivering a piercing bite. The teeth indicate that Campylognathoides may have preyed upon smaller terrestrial animals. Because of its robust forelimbs and proportionally large wing fingers, it would’ve been a fast flyer and may have hunted in manners akin to modern falcons and mastiff bats. Its legs were held sideways and upwards under the body, suggesting an inability to walk while on the ground. 

a Dorygnathus takes a break from fishing

Another Toarcian Stage pterosaur was Dorygnathus. This pterosaur was smaller, with a wingspan of three feet three inches, and has been uncovered in Germany (southern Laurasia). It was a successful pterosaur in its environment and is known from abundant fossils. Its claws show no special adaptations for climbing, so it likely wasn’t a climber unlike the earlier rhamphorhynchid Dimorphodon. Its teeth were long, curved, and sharp near the front of both the upper and lower jaws. These teeth pointed forward and interlocked when the mouth was closed to form a ‘spiky grab.’ This arrangement was perfect for impaling and trapping slippery fish. Smaller, finer teeth at the back of the jaws would’ve held the prey firm as Dorygnathus flew back to its roost. Its jaws formed sharp, toothless points at the very front, hence its name meaning ‘spear-jaw.’ 

Parapsicephalus in flight

The last Early Jurassic pterosaur we’ll look at is Parapsicephalus, which lived in Europe during the Toarcian Stage. It had a three-foot wingspan. In 1970 its skull was the first pterosaur skull discovered in three dimensions, enabling a study of the brain cavity (better brain cavities of other pterosaurs have been discovered since). Parapsicephalus’ brain cast shows well-developed semicircular canals in the ears, giving it a good sense of balance in flight. Its skull was longer than that of Dorygnathus, which it resembled in most other ways. The angle of the ear structure implies Parapsicephalus held its limb horizontally while in flight. 

~ The Middle Jurassic ~ 

an artistic rendition of Augustinaripterus in flight

The ‘black hole’ of the Middle Jurassic is particularly damning for pterosaurs, but recent discoveries in China (then southern Laurasia) have unlocked a treasure trove of Middle Jurassic pterosaurs. The first Middle Jurassic pterosaur we’ll look at was remarkably similar to the Early Jurassic Dorygnathus and Parapsicephalus: like them, Angustinaripterus’ front teeth were long, robust, and curved, pointing forwards to form an inter-meshing ‘prey grab’ that was likely used to snatch fish from the water. Its back teeth were smaller, designed to hold prey that had been caught. Its 6.5-inch-long skull was flat and elongated with a low crest. It’s been estimated to have a wingspan of about 5.25 feet.

a Jeholopterus taking a breather

Another Chinese pterosaur of the Middle Jurassic is perhaps the most interesting of them all. Jeholopterus first appears in the Middle Jurassic around 164 million years ago during the Bathonian Stage and lasted until the Oxfordian Stage (and perhaps even continued into the Early Cretaceous). This pterosaur had a three-foot wingspan and is known from a complete articulated skeleton found in what had been fine lake deposits; the fossilization process revealed hairy coverings and wing membranes. While pterosaurs had a variety of feeding styles – some were fish-catchers, others insectivores, others were filter-feeders or lizard-lovers or crustacean-hunters – Jeholopterus may have had the most unique diet of all. Its broad skull was flattened at the front, giving it a cat-like appearances; its jaws were designed to open wider than those of any other pterosaur; all its teeth were reduced except for a pair in the upper jaws at the front, and these were strong and protruding and deeply rooted in the palate; the claws were large and sharper than those of other pterosaurs whilst its tail was short for a rhamphorhynchid. These specialized designs have led scientists to theorize that Jeholopterus was the ‘vampire bat’ of Jurassic China. Perhaps it used its big claws to anchor to the sides of big dinosaurs while wide-opening its mouth and driving its fang-like front teeth into thick skin to reach blood vessels! If that is indeed the case, Jeholopterus has become my favorite pterosaur.

~ The Late Jurassic ~ 

We know more about pterosaurs of the Late Jurassic than we do of pterosaurs in any of the ages before. Pterosaurs underwent vast radiation during the Late Jurassic, and it was during the Jurassic that witnessed the emergence of the first pterodactyloids from the rhamphorhynchid line. Dozens upon dozens of genera are known, but here we will look at a handful of those flying reptiles that dominated the Late Jurassic skies. We will begin with the rhamphorhynchids and then move on to the emergent pterodactyloids.

an artistic rendition of Darwinopterus

The first pterosaur on our journey is the oddball Darwinopterus. This pterosaur is an oddball because it has characteristics of both the rhamphorhynchids and the pterodactyls: it had the long tail and other features of the rhamphorhynchids, but it also had pterodactyloid features, such as long neck vertebrae and a single skull opening in front of the eyes, called the nasoantorbital fenestrae (in most rhamphorhynchids, the antorbital fenestrae and the nasal opening are separate). Darwinopterus lived 160 million years ago during the Oxfordian stage of the Late Jurassic. It was abundant in its environment, and remains of thirty to forty individuals from up to three different species have been discovered. Its hand bones were relatively short, but the tail was long with over twenty vertebrae. These vertebrae were partially stiffened by long, thin, bony projections. Male species had head crests supported by a thin bony extension of the skull with a serrated top edge; the serrations likely helped anchor an even larger keratin extension, making these pterosaurs remarkably flamboyant for their time.

who wouldn't want a pet Darwinopterus???

The three species of Darwinopterus are distinguished largely on the size and shape of their teeth. The first – D. modularis – was named in 2010, and it had an elongated back end to the skull and widely-spaced ‘spike-like’ teeth likely designed for catching fish. The second species – D. linglongtaensis – was named later in 2010, and it had a shorter and taller skull and shorter, cone-like teeth. The next year, 2011, a third species – D. robustodens – was described with very robust teeth. The paleontologists who deciphered these species believe that these differences in tooth shape suggest that each species occupied a different, non-competing yet overlapping ecological niche. The teeth of each were designed for different food sources: D. modularis, the type species, was designed for catching fish in the lakes and ponds scattered about prehistoric China; D. linglongtaensis may have been insectivorous; and D. modularis may have fed on hard-shelled beetles or even crustaceans.

Darwinopterus is famous for another reason: its eggs and ovaries have been discovered. Regarding the former, its eggs had a parchment-like, soft shell unlike those of modern birds in which the shell is hardened with calcium to protect it from the environment. Soft-shelled eggs like those of Darwinopterus were permeable and allowed water to be absorbed into the egg during development. These types of eggs are more vulnerable than those of birds and dinosaurs, and they are typically buried in soil for protection. Darwinopterus’ eggs weighed about six grams when they were laid, but due to moisture intake, they may have doubled in weight by the time of hatching. One of the paleontologists who studied the fossilized eggs suggested that Darwinopterus laid many small eggs at a time and buried them, and that juveniles could fly upon hatching, requiring little to no parental care – a reproductive strategy similar to reptiles but foreign to birds. However, in 2015 the fossilized mother Darwinopterus was described which had an additional egg present in the body, suggesting that there were two active ovaries, producing a single egg at a time. This would indicate that Darwinopterus laid few eggs and likely cared for its offspring until they were able to leave the nest, just as we find with birds.

Dendrorhynchoides

Our next pterosaur of Late Jurassic China is the Oxfordian stage Dendrorhynchoides . This is one of the smallest known pterosaurs with a wingspan of only fifteen inches. It had a long tail and a short, broad skull with recurved teeth. The scientists who studied the original specimen suggested that Dendrorhynchoides lived an arboreal (or tree-dwelling’) lifestyle as an insectivore. It had large eye sockets and a rounded head, giving it great eyesight and the ability to quickly spot insects and track their movements. Their small body, flexible joints, and small wingspan gave them great agility to catch their prey. The small claws on its hands and feet would enable it to cling to tree bark. Perhaps its body was painted in night colors to help it blend in with its surroundings while ambushing nocturnal insects in the same manner as modern bats or nightjars.

an artistic rendition of Scaphognathus

Scaphognathus lived during the Kimmeridgian and Tithonian stages of Late Jurassic Europe. This rhamphorhynchid had a short head with a fairly rounded, blunt snout (hence the meaning of its name, ‘tub jaw.’) It had a three-foot wingspan, and its jaws were filled with long, upright, sharp-pointed teeth. It had eighteen of these teeth in its upper jaw and ten in its lower jaw. Scaphognathus is known from multiple specimens in various stages of development. These fossils give us a window into pterosaur development. It seems that pterosaur hatchlings grew quickly to adult size and then remained at the adult size the rest of their lives. Modern birds develop in the same manner, unlike most reptiles which tend to grow slowly throughout all their lives but at decreasing rates as they age. Scaphognathus had a large brain for its size, another characteristic more in line with birds than reptiles. Its cerebellum and associated brain lobes were highly-developed, indicating potential for agile movement in support of the idea that smaller pterosaurs made active flapping movements like small birds.

Sordes examines a snail

The rhamphorhynchoid Sordes lived in the Kimmeridgian stage of what is now Late Jurassic Kazakhstan. Its full name, Sordes pilosus, means ‘hairy devil,’ and it gets it name from the hairy pycnofibers that coated much of its body. The first fossils were found in 1960, comprising an all but complete skeleton with imprints of soft body parts, including a thick coat of .25-inch-long ‘hair’ over the head and body and a thinner fur on the wings. This discovery helped prompt a revolution in our understanding of pterosaurs, and it’s a foundational specimen to the idea that most if not all pterosaurs had a furry coat. Sordes was a small pterosaur with short, broad wings; its tail didn’t have a diamond-shaped fin like most rhamphorhynchids, but it was flattened and paddle-like at the end. It had an extra set of wing membranes between the two back legs that stretched down to the ankles, leaving the long tail free.

Anurognathus would make an excellent house-pet

The small pterosaur Anurognathus lived during the Tithonian stage in Late Jurassic Europe. Its name means ‘tail-less jaw,’ and though it’s classified as a rhamphorhynchid, it had pterodactyloid-like features. It had a shortened tail like the pterodactyloids that resembled the fleshy bump of a bird’s tail (called a pygostyl or ‘parson’s nose’). Anurognathus was small and slender with a body the size of a human finger. Its wings were long and slim, giving it a twenty-inch wingspan, and its tiny skull was just an inch-long and formed of bony struts with gaping fenestrae for lightness. The head was deep with a wide, frog-like mouth filled with pin-sized teeth designed for crushing and grinding insect exoskeletons. These teeth suggest a diet of insects caught ‘on the wing,’ in a manner similar to today’s swift or swallow. 

Rhamphorhynchus in flight

The last rhamphorhynchid we’ll look at is the namesake of them all. Rhamphorhynchus lived during the Tithonian stage of the Late Jurassic in both Europe and Africa, indicating a widespread distribution on both Laurasia and Gondwana. This pterosaur gives its name to the long-tailed, short-headed pterosaurs, and its name means ‘beak-snout’ because of its long, narrow, pointed beak. Its fang-like teeth stuck out at all angles from the sides of the jaw, and these teeth were ideal for spearing and trapping fish. It likely skimmed its beak through the water, snapping it shut the instant a fish touched its mouth. Scientists believe it may have had a pelican-like throat pouch for holding its prey. Its pescetarian lifestyle is attested to by fish remains found in the crop and stomach of some specimens. Rhamphorhynchus had an eight-inch-long head and a long tail. Its broad, strong breastbone carried a forward-pointing crest giving wide attachments for wing muscles. Its neck was short and compact, holding the head straight out rather than at an angle as with modern birds. Its wings were stiffened with fine struts of gristle that radiated from the arm bones in the same pattern as a bird’s flight feathers. 

a Pterodactylus strutting its stuff along the seashore

Just as Rhamphorynchus is the namesake for the rhamphorhynchids, so Pterodactylus is the namesake for the long-snouted, short-tailed pterodactyloids. Pterodactylus first appears in the Oxfordian stage of the Late Jurassic around 160 million years ago and survived until the Early Cretaceous 130 million years ago. Its remains have been found in both Europe and Africa, indicating a global distribution on both Laurasia and Gondwana. Multiple species of Pterodactylus have been identified, and though they have linking features indicating they aren’t separate genera, the divergences are vast. Some species were as small as a modern blackbird with wings just twelve inches across; others were giants of their day with an eight-foot wingspan. Pterodactyls – referring here to the variant species of Pterodactylus rather than to the wider ‘family lineage’ of the pterodactyloids – had very short tails and lengthened necks that joined at the base of the skull. Their skulls were thin and light with large weight-saving fenestrae. The main wing membranes attached to the upper leg and upper part of the lower leg, and they had no ‘tail’ membrane between the back legs. The wings were long and narrow due to the elongated hand bones near the wing claws. Pterodactyls had a small, extra flap of wings at the front between wrist and shoulder, called the propatagium. The propatagium was supported by one of the wrist bones, the pteroid, which angled forward and upward. One specimen – just a baby a few weeks old – appeared capable of powered flight. Another specimen shows evidence of a baggy throat pouch that could carry food; perhaps the youngest pterodactyls, not yet able to fly, were hand-delivered food from their mothers? Pterodactylus lived in coastal areas and likely roosted along the shorelines, fishing off-shore.

The pterodactyloid Batrachognathus lived during the Oxfordian and Kimmeridgian stages of the Late Jurassic in what is now modern Kazakhstan. This pterosaur was small with a wingspan of twenty inches, and though it’s currently classified as a pterodactyloid, it also had features of the rhamphorhynchids. Only two specimens are known, both from a prehistoric lakebed. Its name means ‘frog jaw’ in references to its short head and wide mouth. Its blunt, peg-like teeth are designed for catching insects and crushing their carapaces, and it likely flittered over lake surfaces, catching insects in its scoop-like mouth like modern swallows. Its environment was filled with prey such as dragonflies, cicadas, beetles, wasps, caddisflies and mayflies. It had a high, short skull and short tail, and the tail vertebrae were fused together like that of a pterodactyloid. Its wing structure, with short wrists, is more reminiscent of rhamphorynchids.

The pterodactyloid Germanodactylus lived during the Tithonian stage of Late Jurassic Europe. Its remains were found in Germany, hence its name – ‘German finger.’ It had a 4’4” wingspan, and atop its skull was a low, horn-covered, bony crest that ran from the forehead halfway down the beak. It may have roosted hanging upside-down by its toes, like a bat. It had a long, narrow beak with few or no teeth. As pterodactyloids evolved, they consistently shed teeth, and the question is, “Why?” One theory is that they did so because teeth added to the weight that hindered flight (this is thought to be the reason modern birds, descended from avian dinosaurs, eventually shed their teeth). Though Germanodactylus retained a few short, peg-like teeth in the back of its jaws, the front of its beak was toothless, tapering to a horn-covered tip. Its compatriot from the Tithonian, Gallodactylus – meaning ‘Gallic (French) finger’ due to its discovery in France – was slightly smaller with a 3’3” wingspan. Gallodactylus was one of the earliest pterosaurs to develop a crest on the back of its head rather than at the front of the beak. This crest was short and cone-shaped. The skull was long with a narrow beak, and it had slender, sharp, forward-pointing fangs at the front of its mouth and no teeth in the back of the jaws. These fangs likely worked like a ‘fish-fork’ to stab marine prey and snatch it from the water’s surface.

a pair of filter-feeding Ctenochasma

Thus far in our survey of the big-hitting Jurassic pterosaurs, we've seen a variety of feeding styles. Some pterosaurs caught fish, others hunted insects, others may have preyed on small terrestrial creatures such as lizards and mammals, and one may have even been a vampire. In the Late Jurassic another feeding style developed, and it was so successful that multiple pterodactyloid lineages adopted it. This was 'filter-feeding,' in which a creature uses bristles of fine, densely-packed teeth to 'filter' organisms like plankton from the water. Modern filter-feeders include flamingos and baleen whales. Pterodaustro of South America had a four-foot wingspan and elongated, slender, upwardly-curved jaws. Its jaws account for most of the length of its nine-inch head. The lower jaw bristled with thousands of long, fine, densely-packed teeth. Another filter-feeder, this one from Europe, was Ctenochasma. This pterodactyloid’s jaws contained more than 250 fine needle-like teeth that fanned upwards at the tip. Hatchlings possessed sixty, and they grew the rest as they reached adulthood. Ctenochasma embraced filter-feeding as it skimmed over shallow ponds and caught invertebrate larvae and crustaceans in its bristles. Two species of Ctenochasma have been named, one with a crest that likely served as a display structure. The crest was lightweight and made of porous bone. A third filter feeder, Gnathosaurus, lived in Europe and was larger than its filter-feeding brethren with a wingspan of five and a half feet. Its masses of needle-like teeth in long jaws reminded the original discoverers of a crocodile, and Gnathosaurus was first misidentified as a croc. Gnathosaurus’ snout was expanded and spoon-shaped at the end, and it sported a crest that ran down the mid-like of its skull for three-quarters its length. Gnathosaurus lived in the same ecosystems as its contemporary Ctenochasma, indicating that there were enough ponds and lakes to support two competing species of filter-feeders.

a Gnathosaurus prowls a beach at low tide, keeping a wary eye on a pack of small theropod dinosaurs

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