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June 10, 2015

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New analysis downsizes record-breaking dino

June 10, 2015
Courtesy of the University of Liverpool
and World Science staff

A new anal­y­sis pur­ports to down­size a di­no­saur hailed last year as the larg­est known di­no­saur whose weight could be re­liably cal­cu­lat­ed.

Sci­en­tists at the Uni­vers­ity of Liv­er­pool in the U.K. say the an­i­mal, known as Dread­nough­tus, weighs only 30 to 40 tons, not over 60 tons as pre­vi­ously thought. Even the slimmed-down Dread­nough­tus would, how­ev­er, still weigh around as much as sev­en Af­ri­can ele­phants.

The new anal­y­sis, pub­lished in the jour­nal Bi­ol­o­gy Let­ters, takes is­sue with an ear­li­er cal­cula­t­ion pub­lished Sept. 4 in the jour­nal Sci­en­tif­ic Re­ports by re­search­ers at Drexel Uni­vers­ity in Phil­a­del­phia. 

The meth­od orig­i­nally used is “com­mon” and suc­cess­fully used in many cases, but turns out not to have been ap­pli­ca­ble here for var­i­ous rea­sons, ac­cord­ing to the Liv­er­pool sci­en­tists.

Found in Pat­a­go­nia, Ar­gen­ti­na, the huge fos­sil had al­most all of the ma­jor bones in­tact, al­low­ing sci­en­tists to con­fi­dently es­ti­mate its overall size—26 me­ters (a­bout 28 yards) long. Pre­served in rock, it is thought that the an­i­mal was close to matur­ity but not fully grown when it died, and may have grown to be even larg­er.

To es­ti­mate the weight, sci­en­tists orig­i­nally used an equa­t­ion that pre­dicts body mass based on the size of thigh and arm bones. That led to a range of es­ti­mates with the av­er­age be­ing 60 tons.

The Liv­er­pool sci­en­tists said they re-evaluated this af­ter it turned out that oth­er di­no­saurs of its ev­o­lu­tion­ary group, called sauropods, weighed much less than Dread­nough­tus though they were only mar­gin­ally smaller.

The team used a three-di­men­sion­ skele­tal mod­el­ing tech­nique to ex­am­ine body mass more di­rect­ly. This meth­od in­volves math­e­mat­ic­ally re­con­struct­ing a “skin” vol­ume around bones of Dread­nough­tus on a com­put­er and then ex­pand­ing that skin out­line to ac­count for mus­cle, fat and oth­er tis­sues.

The size of ex­pand­ed skin out­line is based on si­m­i­lar da­ta from liv­ing an­i­mals. By ex­plor­ing a range of ex­pan­sions the sci­en­tists said they could bet­ter pre­dict how heavy Dread­nough­tus could real­is­tic­ally have been.

“Es­ti­mat­ing the body mass of an ex­tinct an­i­mal from ap­prox­i­mately 77 mil­lion years ago of this size from only its fos­silized bones is ex­tremely chal­leng­ing and re­lies on the avail­abil­ity of cer­tain da­ta from liv­ing an­i­mals and mod­el­ing tech­niques,” said Karl Bates, one of the in­ves­ti­ga­tors.

“The orig­i­nal meth­od used to cal­culate the mass of the an­i­mal is a com­mon one and has been used suc­cess­fully on many spec­i­mens. The high­est es­ti­mates pro­duced for this par­tic­u­lar gi­ant, how­ev­er, did­n’t quite match up.

“Us­ing dig­it­al mod­el­ing and a da­taset that took in spe­cies, alive and dead, we were able to see that the crea­ture could­n’t be as large as orig­i­nally es­ti­mated.”

“Our anal­y­sis sug­gests that only the low­er es­ti­mates pro­duced by pre­vi­ous meth­ods are plau­si­ble. Es­ti­mates of 60 tons and above do not fit with our cur­rent un­der­stand­ing of the mass char­ac­ter­is­tics of liv­ing land an­i­mals.”

Wheth­er Dread­nough­tus is still a record-breaker is un­cer­tain. Ac­cord­ing to the Drexel Uni­vers­ity group, be­fore its disco­very, anoth­er Pat­a­go­ni­an gi­ant, Elalti­tan, was the di­no­saur with the great­est cal­cula­ble weight at 47 tons. But the Liv­er­pool sci­en­tists sug­gest that a range of large di­no­saurs may have had their weight overes­ti­mated, not just Dread­nough­tus, so the overall pic­ture for large di­no­saur weights is “un­clear.”


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A new analysis purports to downsize a dinosaur hailed last year as the largest known dinosaur whose weight could be reliably calculated. Scientists at the University of Liverpool in the U.K. say the animal, known as Dreadnoughtus, weighs only 30 to 40 tons, not over 60 tons as previously thought. Even the slimmed-down Dreadnoughtus would, however, still weigh around as much as seven African elephants. The new analysis, published in the journal Biology Letter, takes issue with an earlier calculation published Sept. 4 in the journal Scientific Reports by researchers at Drexel University in Philadelphia. The method originally used is “common” and successfully used in many cases, but turns out not to have been applicable here for various reasons, according to the Liverpool scientists. Found in Patagonia, Argentina, the huge fossil had almost all of the major bones intact, allowing scientists to confidently estimate its overall size—26 meters (about 28 yards) long. Preserved in rock, it is thought that the animal was close to maturity but not fully grown when it died, and may have grown to be even larger. To estimate the weight, scientists originally used an equation that predicts body mass based on the size of thigh and arm bones. That led to a range of estimates with the average being 60 tons. The Liverpool scientists said they re-evaluated this after it turned out that other dinosaurs of its evolutionary group, called sauropods, weighed much less than Dreadnoughtus though they were only marginally smaller. The team used a three-dimensional skeletal modeling technique to examine body mass more directly. This method involves mathematically reconstructing a “skin” volume around bones of Dreadnoughtus on a computer and then expanding that skin outline to account for muscle, fat and other tissues. The size of expanded skin outline is based on similar data from living animals. By exploring a range of expansions the scientists said they could better predict how heavy Dreadnoughtus could realistically have been. “Estimating the body mass of an extinct animal from approximately 77 million years ago of this size from only its fossilized bones is extremely challenging and relies on the availability of certain data from living animals and modeling techniques,” said Karl Bates, one of the investigators. “The original method used to calculate the mass of the animal is a common one and has been used successfully on many specimens. The highest estimates produced for this particular giant, however, didn’t quite match up. “Using digital modeling and a dataset that took in species, alive and dead, we were able to see that the creature couldn’t be as large as originally estimated.” “Our analysis suggests that only the lower estimates produced by previous methods are plausible. Estimates of 60 tones and above do not fit with our current understanding of the mass characteristics of living land animals.” Whether Dreadnoughtus is still a record-breaker is uncertain. According to the Drexel University group, before its discovery, another Patagonian giant, Elaltitan, was the dinosaur with the greatest calculable weight at 47 tons. But the Liverpool scientists suggest that a range of large dinosaurs may have had their weight overestimated, not just Dreadnoughtus, so the overall picture for large dinosaur weights is “unclear.”