Tanystropheus is one of those marine reptiles (technically an archosaur) that looked like it came straight out of a cartoon: its body was relatively unremarkable and lizard-like, but its long, narrow neck extended out for a disproportionate length of 10 feet, about as long as the rest of its trunk and tail. Even stranger, from a paleontological perspective, the exaggerated neck of Tanystropheus was supported by only a dozen extremely elongated vertebrae, whereas the long necks of the much longer sauropod dinosaurs of the later Jurassic period (to which this reptile was only distantly related) were assembled from a correspondingly larger number of vertebrae. (The neck of Tanystropheus is so strange that one paleontologist interpreted it, over a century ago, as the tail of a new genus of pterosaur!)
Name: Tanystropheus (Greek for "long-necked one"); pronounced TAN-ee-STROH-fee-us
Habitat: Shores of Europe
Historical Period: Late Triassic (215 million years ago)
Size and Weight: About 20 feet long and 300 pounds
Diet: Probably fish
Distinguishing Characteristics: Extremely long neck; webbed hind feet; quadrupedal posture
Why did Tanystropheus possess such a cartoonishly long neck? This is still a matter of some debate, but most paleontologists believe this reptile perched alongside the shorelines and riverbeds of late Triassic Europe and used its narrow neck as a kind of fishing line, plunging its head into the water whenever a tasty vertebrate or invertebrate swam by. However, it's also possible, though comparatively unlikely, that Tanystropheus led a primarily terrestrial lifestyle, and hoisted up its long neck to feed on smaller lizards perched high up in trees.
A recent analysis of a well-preserved Tanystropheus fossil discovered in Switzerland supports the "fisherman reptile" hypothesis. Specifically, the tail of this specimen shows an accumulation of calcium carbonate granules, which can be interpreted as meaning that Tanystropheus had especially well-muscled hips and powerful hind legs. This would have provided an essential counterweight to this archosaur's comically long neck and prevented it from tumbling into the water when it snagged and attempted to "reel in" a big fish. Helping to confirm this interpretation, another recent study shows that the neck of Tanystropheus only accounted for one-fifth of its body mass, the remainder concentrated in the rear portion of this archosaur's body.