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Dinos may have used long necks “vacuum-cleaner” style

March 23, 2011
Courtesy of The Royal Society
and World Science staff

The staggeringly long necks of some gi­ant di­no­saurs may have served to let them graze widely with­out shift­ing their heavy bod­ies, re­search­ers say.

The pro­posed feed­ing strat­e­gy, which sci­en­tists lik­en to the ac­tion of an old-fash­ioned vac­u­um clean­er, stands in con­trast to some old­er be­liefs about the long neck, some­times thought to have been used for giraffe-like graz­ing in trees.

Artist's re­pre­senta­tion of a late sau­ro­pod dino­saur. (Cour­tesy U.S. Bu­reau of Land Ma­nage­ment)

The new re­search, pub­lished the jour­nal Bi­ol­o­gy Let­ters on­line March 23, ex­am­ines the sauro­pods—a ma­jor line­age of plant-eating di­no­saurs with im­mense bod­ies and long necks and tails. 

Mostly walk­ing on all fours, they in­clud­ed such fa­vor­ite mu­se­um pieces as Dip­lo­do­cus and Ap­ato­saur­us, form­erly known as Bron­to­sau­rus or “thun­der liz­ard.” The larg­est sauro­pods were over 30 me­ters, or about 100 feet, long and weighed an es­ti­mat­ed 30 tons.

Some sci­en­tists had al­ready dis­put­ed the idea that the sauro­pods grazed high up in trees, ar­gu­ing that just lift­ing those long necks for all that time would cost more en­er­gy than it was worth. 

The new re­search uses cal­cula­t­ions to dem­on­strate, the au­thors said, that brows­ing on the ground would have been an ef­fi­cient way for the mas­sive crea­tures to feed. The sci­en­tists took their in­spira­t­ion from old-fash­ioned, cylinder-style vac­u­um clean­ers. While the out­dat­ed con­trap­tions might in­i­tially seem very dif­fer­ent from di­no­saurs, in fact they share the char­ac­ter­is­tics of large, pon­der­ous bod­ies and long thin necks. 

“The long neck of the Sau­ro­pods might have been an adapta­t­ion to al­low less move­ment of the ex­cep­tion­ally heavy body of these an­i­mals while feed­ing,” the re­search­ers wrote. The lengthy necks could have “al­lowed a great­er ar­ea of food to be ex­ploited from a giv­en po­si­tion.”

The an­i­mals may have for­aged both in the trees and on the ground, added the sci­en­tists, based at Liv­er­pool John Moores Un­ivers­ity and the Un­ivers­ity of Glas­gow in the U.K. “It is pos­si­ble that a giv­en type of sau­ro­pod used both high and low for­ag­ing,” they wrote.

Ac­cord­ing to the Un­ivers­ity of Cal­i­for­nia Mu­se­um of Pa­le­on­tol­ogy, sauropods were one of the most long-lived di­no­saur line­ages, span­ning some 100 or so mil­lion years, but were most abun­dant around 140 mil­lion years ago. Some lat­er Sau­ro­pods sported ru­di­men­ta­ry body ar­mor.

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The extremely long necks of some giant dinosaurs may have served to let them graze widely without shifting their heavy bodies, researchers say. The proposed feeding strategy, which scientists liken to the action of an old-fashioned vacuum cleaner, stands in contrast to some older beliefs about the long neck, sometimes thought to have been used for giraffe-like grazing in trees. The new research, published the journal Biology Letters online March 23, examines the sauropods—a major lineage of plant-eating dinosaurs with immense bodies and long necks and tails. Mostly walking on all fours, they included such favorite museum pieces as Diplodocus and Apatosaurus, formerly known as Brontosaurus or “thunder lizard.” The largest sauropods were over 30 meters, or about 100 feet, long and weighed an estimated 30 tons. Some scientists had already disputed the idea that the sauropods grazed high up in trees, arguing that just lifting those long necks for all that time would cost more energy than it was worth. The new research uses mathematical calculations to demonstrate, the authors said, that browsing on the ground would have been an efficient way for the massive creatures to feed.The scientists took their inspiration from old-fashioned, cylinder-style vacuum cleaners. While the outdated contraptions might initially seem very different from dinosaurs, in fact they share the characteristics of large, ponderous bodies and long thin necks. “By analogy to old style vacuum cleaners, the long neck of the Sauropods might have been an adaptation to allow less movement of the exceptionally heavy body of these animals while feeding,” the researchers wrote. The lengthy necks could have “allowed a greater area of food to be exploited from a given position.” The animals may have foraged both in the trees and on the ground, added the scientists, based at at Liverpool John Moores University and the University of Glasgow in the U.K. “It is possible that a given type of Sauropod used both high and low foraging,” they wrote. According to the University of California Museum of Paleontology, sauropods were one of the most long-lived dinosaur lineages, spanning some 100 or so million years, but were most abundant around 140 million years ago. Some later Sauropods sported rudimentary body armor.