Giants of the dinosaur world (Sauropods) produced eggs no larger than an ostrich egg
Friday, September 22nd, 2023
Sauropods weighed 50 times more than an ostrich but weight of their eggs was akin to ostrich eggs, 1.5kg. Isn’t it puzzling that eggs of giant dinosaurs are so very small?
Many researchers are of the opinion that sauropods eggs are small enough to be equal to ostrich eggs because they took quite a long time to incubate. Weight of ostrich is 50 times less than sauropods so the fact that its eggs weighs equal to eggs of sauropods is really difficult to digest. Relatively small size of dinosaur eggs has always puzzled scientists.
A recent research concludes that the considerably long incubation time required for sauropod embryos to develop and hatch may have been a vital constraint. This, the researchers say, could explain the small individual size of sauropod eggs. Professor Ruxton, of the School of Biology at University of St Andrews, explained, “The living bird with the largest eggs, the ostrich, has to incubate its eggs for 42 days; during which time many eggs are lost to predators. An ostrich weighs about 100kg and lays a 1.5kg egg; a sauropod dinosaur might be 50 times heavier than an adult ostrich but its eggs were only a little heavier than an ostrich egg.” He added, “Both individual egg size and clutch size in sauropods are smaller than might be expected for such enormous creatures, relative to modern egg-laying animals. Some people might find it a bit disappointing that giant dinosaurs didn’t lay equally giant eggs – but it’s very satisfying to think that we might finally understand why.”
The team, which had biologists from George Mason University in Virginia and the University of Lincoln, used data from modern reptiles and birds to examine factors affecting clutch size in this group of dinosaurs. They estimated that the time span from laying to hatching of eggs was between 65 and 82 days. Long incubation time quiet naturally increased the risk of predation, which combined with the relatively low temperatures expected in the nest, may have been an important factor in limiting the egg and clutch size.
The scientists believe that although having larger eggs may have been gainful because of larger hatchling size, this may have been dwarfed by the bigger risk of predation during the egg stage. They also state that by laying their eggs in small clutches, possibly in multiple nesting sites, female dinosaurs found an innovative way of having a better chance of protecting their offspring from predation.
Dr Charles Deeming, from University of Lincoln, explained: “We think that a long incubation period of sauropods is likely to have led to very high mortality through predation. We suggest that the females laid their eggs in small clutches, possibly in different nesting sites, as an adaptive strategy to mitigate the high predation risk associated with long time of exposure in the egg stage.”
The team is of the opinion that their inferences could be extended to other groups of dinosaurs.