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Sauropods are thought to have retained the claws on their hind feet for the purpose of nest digging, right? Even the derived titanosaurs without any manual phalanges still had unguals/claws on their hind feet. From: dinosaur-l-request@usc.edu <dinosaur-l-request@usc.edu> on behalf of Dann Pigdon <dannj@alphalink.com.au>
Sent: Wednesday, July 3, 2019 7:21 PM To: dinosaur-l@usc.edu Subject: Re: [dinosaur] Fwd: Re: T. rex hunting Alamosaurus > Gregory Paul wrote: > > Sauropod nests are known and documented. They have the poorly organized > structure typical of reptiles that immediately abandon their nests, they are > not like the better organized nests of some dinosaurs and all known birds > that at least care for the eggs (megapodes do not care for their > hatchlings). At least one paper (Hechenleitner et al 2015) has compared sauropod nests to extant megapode nests. Several papers have come to the conclusion that some sauropod nests were excavated via scratch digging of the hind feet (Vila et al 2010, Fowler & Hall 2010, etc). That would suggest that sauropods both constructed and laid their eggs without being able to see what they were doing. Depending on how they covered the eggs after they were laid, that may have also been achieved without the aid of sight. The poorly organised structure of some sauropod nests may have more to do with a very large animal attempting to build something relatively small (and with uncharacteristic delicateness) without the benefit of sight. Nest guarding behaviour isn't unheard of amongst non-theropod egg layers. Even squamates and tuataras do it. The degree of organisation of the nest structure may not be a good indicator of whether or not the eggs were guarded. Some behavioural adaptations don't leave tangible evidence behind, or if they do, can leave decidedly ambiguous traces. This is never more frustrating than when dealing with an entirely extinct lineage with no extant analogue. One interesting aspect of Refsnider et al's 2009 paper on tuatara nest guarding is the conclusion that it may have more to do with protecting the nest from other female tuataras than for defence against egg predators. When good nesting spots are at a premium, female tuataras have few qualms about destroying the nest of another female in order to claim the nest site for their own eggs. -- Dann Pigdon |