Pterosaurs may have Cared for their Young

Some imagine the Cretaceous and Jurassic Ages as a time when the earth was strange and full of terrifying monsters.    The earth was a vast wilderness then, dangerous perhaps for most creatures, but it was no more strange or terrifying than the world we live in today–the Anthropocene with its genocides, terrorism, potential nuclear war, and extensive environmental destruction caused by a single dominant species.  The dinosaur world hosted species different from those of modern day earth, but these organisms were part of ecosystems recognizably comparable to those of today.  For example fish-eating pterosaurs nested in communal colonies, not unlike present day heron and egret rookeries.  Pterosaurs were not dinosaurs but instead were flying reptiles–the only vertebrates besides birds and bats to evolve the ability to fly. After their initial evolution the early Jurassic pterosaurs radiated into many species and occupied different ecological niches.  From the middle of the Jurassic until their extinction at the end of the Cretaceous 66 million years ago, there were probably about as many species of pterosaurs living in the world as there are birds today.  Evidence from 1 site in northwest China suggests pterosaurs, like so many modern day vertebrates, cared for their young.

Paleontologists found 215 fossilized eggs of a species of pterosaur known as Hamipterus tianshanensis, a fish-eating species that nested communally.  The fossils from this site date to about 120 million years BP, and they are from many generations. The nests were located next to a lake at the time of deposition.  Apparently, pterosaurs used this site annually.  Perhaps it was difficult for predators to access.  Some of the eggs contain visible embryos.  The embryos show well developed legs but underdeveloped wing bones.  This suggests the hatchlings couldn’t fly and depended upon parental care for food until their wings developed.  However this conclusion isn’t certain.  The fossils are of an embryonic stage, not actual hatchlings.  The wing bones may have developed at a later embryonic stage.

Image result for pterodactyl vs green lantern

Artist’s representations of pterosaurs have changed over the years.  In this old issue of Green Lantern from the early 1970s the pterosaur is larger than a man, featherless, and conveniently yellow.  Green Lantern’s power ring doesn’t work against yellow objects.  The wingspans of some species of pterosaurs were longer than the length of a man, but they could not have seized and carried a man away.  They were able to leap straight up and fly though, unlike large modern bird species which must take a running start.

Image result for hamipterus tianshanensis

This more modern representation of pterosaurs by Masato Hattori, a depiction of Hamipterus tianshanensis, shows the reptile covered with hair-like feather structures.  It also had teeth.

Cretaceous-aged outcroppings occur near Columbus, Georgia and the Chattahoochee River.  These are the only regions in the state where Cretaceous fossils have been found.  David Schwimmer, a professor at Columbus State, excavated 3 pterosaur wing bones from an outcropping here–the only evidence pterosaurs formerly existed in the state.

References:

Deeming, Charles

“How Pterosaurs Bred”

Science 358 (6367) December 2017

Wang, Xi; et. al.

“Egg Accumulation with 3-D Embryos Provides Insights into the Life History of a Pterosaur”

Science 358 (6367) December 2017

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One Response to “Pterosaurs may have Cared for their Young”

  1. ina puustinen-westerholm Says:

    Good job as usual. When the wind-rains event..forecast for the left coast..today arrives..we shall imagine..the calls..from such early critters. 😉

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