"Long before it's in the papers"
January 27, 2015


Intact pterosaur eggs reported found with parents

June 10, 2014
Courtesy of Cell Press
and World Science staff

Re­search­ers are re­port­ing the find­ing of the first three-di­men­sion­ly pre­served eggs of pter­o­saurs, fly­ing rep­tiles with wing­spans up to half the length of a ten­nis court.

The eggs, found in Chi­na, turned up among at least doz­ens of pter­o­saur fos­sils, rep­re­sent­ing a new spe­cies called Hamip­terus tian­sha­nen­sis, sci­en­tists re­ported.

Ecological reconstruction of Hamipterus. (Credit: Chuang Zhao)

The an­i­mals lived to­geth­er in col­o­nies, ac­cord­ing to the re­search­ers, who pre­sented their work in the jour­nal Cur­rent Bi­ol­o­gy on June 5.

“Five eggs are three-di­men­sion­ly pre­served, and some are really com­plete,” said Xi­aolin Wang of the Chin­ese Acad­e­my of Sci­ences, who was in­volved with the re­search. It was most ex­cit­ing to find many male and female pter­o­saurs and their eggs pre­served to­geth­er, he added.

The pter­o­saur fos­sil rec­ord has gen­er­ally been poor, with lit­tle in­forma­t­ion about their popula­t­ions, the re­search­ers say. Only four iso­lat­ed and flat­tened pter­o­saur eggs were known to sci­ence be­fore now.

The rest­ing place of the pter­o­saurs now de­scribed was un­cov­ered in 2005 in the Turpan-Hami Ba­sin, south of the Tian Shan Moun­tains in Xin­jiang, north­west­ern Chi­na. The fos­sil-rich ar­ea is thought to pos­sibly har­bor thou­sands of bones. Wang said sed­i­ments in the ar­ea sug­gest that the pter­o­saurs died in a large storm about 120 mil­lion years ago in the Early Cre­ta­ceous pe­ri­od.

The re­search­ers ex­am­ined the largely in­tact pter­o­saur egg spec­i­mens to find that they were pli­a­ble, with a thin egg­shell out­side and a soft, thick mem­brane in­side, si­m­i­lar to the eggs of some mod­ern-day snakes. The re­search­ers’ ob­serva­t­ions of 40 male and female in­di­vid­u­als sug­gested dif­fer­ences be­tween the sexes in the size, shape, and ro­bust­ness of their head crests.

The com­bina­t­ion of many pter­o­saurs and eggs strongly in­di­cates the pres­ence of a nest­ing site near­by and in­di­cates that this spe­cies de­vel­oped gre­gar­i­ous be­hav­ior, the re­search­ers said. Hamip­terus most likely bur­ied their eggs in sand along the shore of an an­cient lake to pre­vent them from dry­ing out, they added. While the new fos­sils are thought to shed light on their re­pro­duc­tive strat­e­gy, de­vel­op­ment, and be­hav­ior, there’s still much left to learn about them.

“Sites like the one re­ported here pro­vide fur­ther ev­i­dence re­gard­ing the be­hav­ior and bi­ol­o­gy of this amaz­ing group of fly­ing rep­tiles that has no par­al­lel in mod­ern time,” the re­search­ers wrote.

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Researchers are reporting the finding of the first three-dimensionally preserved eggs of pterosaurs, flying reptiles with wingspans as wide as up to half a tennis court. The eggs, found in China, turned up among at least dozens of pterosaur fossils, representing a new genus and species called Hamipterus tianshanensis, scientists reported. The animals lived together in colonies, according to the researchers, who presented their work in the journal Current Biology on June 5. “Five eggs are three-dimensionally preserved, and some are really complete,” said Xiaolin Wang of the Chinese Academy of Sciences, who was involved with the research. It was most exciting to find many male and female pterosaurs and their eggs preserved together, he added. The pterosaur fossil record has generally been poor, with little information about their populations, the researchers say. Only four isolated and flattened pterosaur eggs were known to science before now. The resting place of the pterosaurs now described was uncovered in 2005 in the Turpan-Hami Basin, south of the Tian Shan Mountains in Xinjiang, northwestern China. The fossil-rich area is thought to possibly harbor thousands of bones, including three-dimensional male and female skulls. Wang said sediments in the area suggest that the pterosaurs died in a large storm about 120 million years ago in the Early Cretaceous period. The researchers examined the largely intact pterosaur egg specimens to find that they were pliable, with a thin eggshell outside and a soft, thick membrane inside, similar to the eggs of some modern-day snakes. The researchers’ observations of 40 male and female individuals suggested differences between the sexes in the size, shape, and robustness of their head crests. The combination of many pterosaurs and eggs strongly indicates the presence of a nesting site nearby and indicates that this species developed gregarious behavior, the researchers say. Hamipterus most likely buried their eggs in sand along the shore of an ancient lake to prevent them from drying out, they added. While the new fossils shed light on the reproductive strategy, development, and behavior of pterosaurs, there is still plenty left to learn about them. “Sites like the one reported here provide further evidence regarding the behavior and biology of this amazing group of flying reptiles that has no parallel in modern time,” the researchers wrote.