Pelycosaur Pictures and Profiles

Meet the Pelycosaurs of the Paleozoic Era

From the late Carboniferous to the early Permian periods, the largest land animals on earth were pelycosaurs, primitive reptiles that subsequently evolved into therapsids (the mammal-like reptiles that preceded true mammals). On the following slides, you'll find pictures and detailed profiles of over a dozen pelycosaurs, ranging from Casea to Varanops.

Casea

Name:

Casea (Greek for "cheese"); pronounced kah-SAY-ah

Habitat:

Woodlands of western Europe and North America

Historical Period:

Late Permian (255 million years ago)

Size and Weight:

About four feet long and a few hundred pounds

Diet:

Plants

Distinguishing Characteristics:

Short legs; quadrupedal posture; fat, piglike trunk

Sometimes, a name just fits. Casea was a low-slung, slow-moving, fat-bellied pelycosaur that looked just like its moniker--which is Greek for "cheese." The explanation for this reptile's strange build was that it had to pack digestive equipment lengthy enough to process the tough vegetation of the late Permian period into a limited amount of trunk space. In most regards, Casea looked virtually identical to its more famous cousin Edaphosaurus, except for the lack of a sporty-looking sail on its back (which may have been a sexually selected characteristic).

Cotylorhynchus

Name:

Cotylorhynchus (Greek for "cup snout"); pronounced COE-tih-low-RINK-us

Habitat:

Swamps of North America

Historical Period:

Middle Permian (285-265 million years ago)

Size and Weight:

About 15 feet long and one ton

Diet:

Plants

Distinguishing Characteristics:

Large, swollen trunk; small head

Cotylorhynchus had the classic body plan of the large pelycosaurs of the Permian period: a huge, bloated trunk (the better to hold all of the intestines it needed to digest tough vegetable matter), a tiny head, and stubby, splayed legs. This early reptile was probably the largest land animal of its time (superannuated adults may have reached two tons in weight), meaning that full-grown individuals would have been virtually immune from predation by the much wimpier predators of their day. One of the closest relatives of Cotylorhynchus was the equally ungainly Casea, whose name is Greek for "cheese."

Ctenospondylus

Name:

Ctenospondylus (Greek for "comb vertebra"); pronounced STEN-oh-SPON-dih-luss

Habitat:

Swamps of North America

Historical Period:

Late Carboniferous-Early Permian (305-295 million years ago)

Size and Weight:

About 10 feet long and a few hundred pounds

Diet:

Meat

Distinguishing Characteristics:

Low-slung belly; quadrupedal posture; sail on back

Beyond its marked resemblance to Dimetrodon--both of these ancient creatures were large, low-slung, sail-backed pelycosaurs, a widespread family of reptiles that preceded the dinosaurs--there isn't much to say about Ctenospondylus, except that its name is much less pronounceable than that of its more famous relative. Like Dimetrodon, Ctenospondylus was probably the top dog, food-chain-wise, of early Permian North America, since few other carnivores came close to it in size or appetite.

Dimetrodon

Far and away the most famous of all the pelycosaurs, Dimetrodon is often mistaken for a true dinosaur. The most notable feature of this ancient reptile was the sail of skin on its back, which probably evolved as a way to regulate body temperature. See 10 Facts About Dimetrodon

Edaphosaurus

Edaphosaurus looked a lot like Dimetrodon: both of these pelycosaurs had large sails running down their backs, which probably helped to maintain their body temperatures (by radiating away excess heat and absorbing sunlight). See an in-depth profile of Edaphosaurus

Ennatosaurus

Name:

Ennatosaurus (Greek for "the ninth lizard"); pronounced en-NAT-oh-SORE-us

Habitat:

Swamps of Siberia

Historical Period:

Middle Permian (270-265 million years ago)

Size and Weight:

About 15-20 feet long and one or two tons

Diet:

Plants

Distinguishing Characteristics:

Large size; low-slung posture

Multiple fossils of Ennatosaurus--including early and late juveniles--have been discovered at a single fossil site in remote Siberia. This pelycosaur, a type of ancient reptile that preceded the dinosaurs, was typical of its kind, with its low-slung, swollen body, small head, splayed limbs and considerable bulk, though Ennatosaurus lacked the distinctive sail seen on other genera like Dimetrodon and Edaphosaurus. It's unknown what size a mature individual might have attained, though paleontologists speculate that one or two tons wasn't out of the question.

Haptodus

Name:

Haptodus; pronounced HAP-toe-duss

Habitat:

Swamps of the northern hemisphere

Historical Period:

Late Carboniferous-Early Permian (305-295 million years ago)

Size and Weight:

About five feet long and 10-20 pounds

Diet:

Small animals

Distinguishing Characteristics:

Small size; squat body with long tail; quadrupedal posture

Although it was significantly smaller than later, more famous pelycosaurs like Dimetrodon and Casea, Haptodus was an unmistakable member of that pre-dinosaur reptilian breed, the giveaways being its squat body, small head and splayed rather than upright-locked legs. This widespread creature (its remains have been found all across the northern hemisphere) occupied an intermediate position in the Carboniferous and Permian food chains, feeding on insects, arthropods and smaller reptiles and being preyed on in turn by the larger therapsids ("mammal-like reptiles") of its day.

Ianthasaurus

Name:

Ianthasaurus (Greek for "Iantha River lizard"); pronounced ee-ANN-tha-SORE-us

Habitat:

Swamps of North America

Historical Period:

Late Carboniferous (305 million years ago)

Size and Weight:

About three feet long and 10-20 pounds

Diet:

Probably insects

Distinguishing Characteristics:

Small size; sail on back; quadrupedal posture

As pelycosaurs (a family of reptiles that preceded the dinosaurs) go, Ianthasaurus was fairly primitive, prowling the swamps of Carboniferous North America and feeding (as far as can be inferred from the anatomy of its skull) on insects and possibly small animals. Like its bigger and more famous cousin, Dimetrodon, Ianthasaurus sported a sail, which it probably used to help regulate its body temperature. As a whole, pelycosaurs represented a dead end in reptile evolution, disappearing off the face of the earth by the end of the Permian period.

Mycterosaurus

Name:

Mycterosaurus; pronounced MICK-teh-roe-SORE-us

Habitat:

Swamps of North America

Historical Period:

Middle Permian (270 million years ago)

Size and Weight:

About two feet long and a few pounds

Diet:

Probably insects

Distinguishing Characteristics:

Small size; low-slung body; quadrupedal posture

Mycterosaurus is the smallest, most primitive genus yet discovered of the family of pelycosaurs known as varanopsidae (exemplified by Varanops), which resembled modern monitor lizards (but were only distantly related to these extant creatures). Not much is known about how Mycterosaurus lived, but it probably scuttled across the swamplands of middle Permian North America feeding on insects and (possibly) small animals. We do know that pelycosaurs as a whole went extinct by the end of the Permian period, outcompeted by better-adapted reptile families like archosaurs and therapsids.

Ophiacodon

Name:

Ophiacodon (Greek for "snake tooth"); pronounced OH-fee-ACK-oh-don

Habitat:

Swamps of North America

Historical Period:

Late Carboniferous-Early Permian (310-290 million years ago)

Size and Weight:

About 10 feet long and 100 pounds

Diet:

Fish and small animals

Distinguishing Characteristics:

Large size; long, narrow head; quadrupedal posture

One of the largest land animals of the late Carboniferous period, the hundred-pound Ophiacodon may have been the apex predator of its day, feeding opportunistically on fish, insects, and small reptiles and amphibians. This North American pelycosaur's legs were a bit less stumpy and splayed than those of its closest relative Archaeothyris, and its jaws were relatively massive, so it would have had little difficulty chasing down and eating its prey. (As successful as it was 300 million years ago, though, Ophiacodon and its fellow pelycosaurs had disappeared from the face of the earth by the close of the Permian period.)

Secodontosaurus

Name:

Secodontosaurus (Greek for "dry-toothed lizard"); pronounced SEE-coe-DON-toe-SORE-us

Habitat:

Swamps of North America

Historical Period:

Early Permian (290 million years ago)

Size and Weight:

About 10 feet long and 200 pounds

Diet:

Probably insects

Distinguishing Characteristics:

Large size; narrow, crocodile-like snout; sail on back

If you saw a fossil of Secondontosaurus without its head, you'd probably mistake it for its close relative Dimetrodon: these pelycosaurs, a family of ancient reptiles that preceded the dinosaurs, shared the same low-slung profile and back sails (which were probably used as a means of temperature regulation). What set Secodontosaurus apart was its narrow, crocodile-like, tooth-studded snout (hence this animal's nickname, the "fox-faced finback"), which hints at a very specialized diet, perhaps termites or small, burrowing therapsids. (By the way, Secondontosaurus was a very different animal than Thecodontosaurus, a dinosaur that lived tens of millions of years later.)

Sphenacodon

Name:

Sphenacodon (Greek for "wedge tooth"); pronounced sfee-NACK-oh-don

Habitat:

Swamps of North America

Historical Period:

Early Permian (290 million years ago)

Size and Weight:

About eight feet long and 100 pounds

Diet:

Small animals

Distinguishing Characteristics:

Large, powerful jaws; strong back muscles; quadrupedal posture

Like its more famous relative of a few million years later, Dimetrodon, Sphenacodon possessed elongated, well-muscled vertebra, but lacked a corresponding sail (meaning it probably used these muscles to lunge suddenly at prey). With its massive head and powerful legs and trunk, this pelycosaur was one of the most evolved predators of the early Permian period, and possibly the most nimble land animal until the evolution of the first dinosaurs toward the end of the Triassic period, tens of millions of years later.

Varanops

Name:

Varanops (Greek for "monitor lizard faced"); pronounced VA-ran-ops

Habitat:

Swamps of North America

Historical Period:

Late Permian (260 million years ago)

Size and Weight:

About five feet long and 25-50 pounds

Diet:

Small animals

Distinguishing Characteristics:

Small head; quadrupedal posture; relatively long legs

Varanops' claim to fame is that it was one of the last pelycosaurs (a family of reptiles that preceded the dinosaurs) on the face of the earth, persisting into the late Permian period long after most of its pelycosaur cousins, notably Dimetrodon and Edaphosaurus, had gone extinct. Based on its similarity to modern monitor lizards, paleontologists speculate that Varanops led a similar, slow-moving lifestyle; it probably succumbed to increasing competition from the more advanced therapsids (mammal-like reptiles) of its time.