"Long before it's in the papers"
January 07, 2016


Dinos may have made “love nests” to show off

Jan. 7, 2016
Courtesy of University of Colorado Denver
and World Science staff

Di­no­saurs en­gaged in mat­ing be­hav­ior si­m­i­lar to mod­ern birds, leav­ing fos­sil ev­i­dence be­hind in 100-mil­lion year old rocks, ac­cord­ing to new re­search.

Pa­le­on­tol­ogist Mar­tin Lock­ley of the Un­ivers­ity of Col­o­rad­o Den­ver led a re­search team that dis­cov­ered what he called large “scrapes” in pre­his­tor­ic Da­ko­ta sand­stone in west­ern Col­o­rad­o. 

Artists’ reconstruction of di­no­saurs en­gaged in sex­ual dis­play (art­work by Lida Xing and Yu­jiang Han)

The team described the scrapes as si­m­i­lar to those left behind from mod­ern birds’ “nest scrape dis­play” or “scrape cer­e­monies.” in these, males show off their abil­ity to pro­vide by dig­ging pre­tend nests for po­ten­tial mates.

“These are the first sites with ev­i­dence of di­no­saur mat­ing dis­play rit­u­als ev­er dis­cov­ered, and the first phys­i­cal ev­i­dence of court­ship be­hav­ior,” Lock­ley said. “These huge scrape dis­plays fill in a mis­sing gap in our un­der­stand­ing of di­no­saur be­hav­ior.”

The study was pub­lished Jan. 7 in the jour­nal Sci­en­tif­ic Re­ports.

Lock­ley, an ex­pert on di­no­saur foot­prints, re­ported ev­i­dence of more than 50 scrapes, some as large as bath­tubs, in an ar­ea where tracks of both meat-eating and plant-eating di­no­saurs have al­so been con­firmed. 

The re­search­ers said they found dis­play are­nas, al­so called leks, in two Na­t­ional Con­serva­t­ion Ar­eas Dominguez-Escalante and Gun­ni­son Gorge on prop­er­ty per­mit­ted by the U.S. Bu­reau of Land Man­age­ment near Del­ta, Colo. Lock­ley al­so de­scribed ev­i­dence of mat­ing ar­e­as at Di­no­saur Ridge, a Na­t­ional Nat­u­ral Land­mark, just west of Den­ver.

The new ev­i­dence sup­ports the­o­ries about the na­ture of di­no­saur mat­ing dis­plays and an ev­o­lu­tion­ary force known as sex­u­al se­lec­tion, Lock­ley and col­leagues ar­gued. Since pre­his­tor­ic times, males look­ing for mates, have driv­en off weaker ri­vals. Fe­ma­les, mean­while, have cho­sen the most im­pres­sive male per­form­ers as con­sorts.

Si­m­i­lar sex­u­al se­lec­tion be­hav­iors are com­mon in mam­mals and birds. But un­til now sci­en­tists could only spec­u­late about di­no­saur mat­ing be­hav­ior, as­sum­ing it might be si­m­i­lar to that of their mod­ern rel­a­tives, the birds.

“The scrape ev­i­dence has sig­nif­i­cant im­plica­t­ions,” said Lock­ley. “This is phys­i­cal ev­i­dence of pre-historic fore­play that is very si­m­i­lar to birds to­day. Mod­ern birds us­ing scrape cer­e­mo­ny court­ship usu­ally do so near their fi­nal nest­ing sites. So the fos­sil scrape ev­i­dence of­fers a tan­ta­liz­ing clue that di­no­saurs in “heat” may have gath­ered here mil­lions of years ago to breed and then nest near­by.”

Lock­ley and his team could­n’t re­move the scrape marks with­out dam­ag­ing them, so in­stead cre­at­ed 3-D im­ages of the scrapes, as well as mak­ing rub­ber molds and fi­ber­glass cop­ies of the scrapes that are be­ing stored at the Den­ver Mu­se­um of Na­ture & Sci­ence.

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Dinosaurs engaged in mating behavior similar to modern birds, leaving the fossil evidence behind in 100 million year old rocks, according to new research. Paleontologist Martin Lockley of the University of Colorado Denver led a research team that discovered what they described as large “scrapes” in the prehistoric Dakota sandstone of western Colorado. These scrapes, they said, are similar to “nest scrape display” or “scrape ceremonies” among modern birds, where males show off their ability to provide by digging pretend nests for potential mates. “These are the first sites with evidence of dinosaur mating display rituals ever discovered, and the first physical evidence of courtship behavior,” Lockley said. “These huge scrape displays fill in a missing gap in our understanding of dinosaur behavior.” The study was published Jan. 7 in the journal Scientific Reports. Lockley, an expert on dinosaur footprints, reported evidence of more than 50 scrapes, some as large as bathtubs, in an area where tracks of both meat-eating and plant-eating dinosaurs have also been confirmed. The researchers said they found display arenas, also called leks, in two National Conservation Areas Dominguez-Escalante and Gunnison Gorge on property permitted by the U.S. Bureau of Land Management near Delta, Colo. Lockley also described evidence of mating areas at Dinosaur Ridge, a National Natural Landmark, just west of Denver. The new evidence supports theories about the nature of dinosaur mating displays and an evolutionary force known as sexual selection, Lockley and colleagues argued. Since prehistoric times, males looking for mates, have driven off weaker rivals. Females, meanwhile, have chosen the most impressive male performers as consorts. Similar sexual selection behaviors are common in mammals and birds. But until now scientists could only speculate about dinosaur mating behavior, assuming it might be similar to that of their modern relatives, the birds. “The scrape evidence has significant implications,” said Lockley. “This is physical evidence of pre-historic foreplay that is very similar to birds today. Modern birds using scrape ceremony courtship usually do so near their final nesting sites. So the fossil scrape evidence offers a tantalizing clue that dinosaurs in “heat” may have gathered here millions of years ago to breed and then nest nearby.” Lockley and his team couldn’t remove the scrape marks without damaging them, so instead created 3-D images of the scrapes, as well as making rubber molds and fiberglass copies of the scrapes that are being stored at the Denver Museum of Nature & Science.