https://www.nature.com/articles/srep18952Researchers some years ago found in the Dakota Formation of Colorado (Cenomanian age, good for preserving trackways and some plants, less so skeletons) strange collections of footprints scraping the ground. The prints were identifiably those of a three-toed ~16 foot theropod and there were collections of adults/subadults of various sizes in the same place, preserved well. These scrapings are most similar to those formed by modern shorebirds in mating leks.>The sharply-terminated scratch marks found in association with diagnostic theropod tracks represent active theropod scraping or scratching. The most complete theropod tracks include a large Irenesauripus-like27,28 left theropod track on the left side of the holotype scrape (Fig. 3a) and a smaller right theropod track associated with the right side of a shallow paratype scrape (Fig. 3c). The variable size and depth of the scrapes, indicate different levels of activity and persistence by different sized theropods, which based on footprint length had hip heights between ~1.0 and ~2.0m29 and full body lengths between ~2.5 and ~5.0m. This implies either two or more different species, or co-occurrence of conspecific adults and sub-adults of quite different sizes. Elapsed time between scraping episodes cannot be estimated accurately, but was likely short given the similar, good preservation of all scrapes.If it is true that a 2.5-5m long obligate carnivores were lek mating in a specific spot and scraping to impress the ladies, and each area has up to 60 PRESERVED scrapes, how were so many large predators in the same place? You don't get a dozen polar bears all in the same place trying to get laid. What are all the dinos eating? modern apex predators have low population densities. Is the radius out from the site to get food practical for them all to eat? Is this a sign that large theropods had slower metabolisms than mammal predators? Do crocodilians lek at all?
And if the male dinosaurs were going hungry while they lek mated, which is not unreasonable considering plenty of modern male animals will ignore their own safety and lose body mass in an attempt to reproduce during the breeding season with repeated displays, how long can such a big predatory animal even go without food and be in the same place for? A huge walking-distance radius around them is going to be basically devoid of prey after not very long, no?
>>5164954Wouldn't the expectation be that there was just a lot more biomass for most of the Mesozoic? The Earth was generally substantially warmer than today, and wasn't post-mass extinction (both the end of the last Ice Age and the Anthropocene). More large predators just sounds typical if you had more of everything up and down the food chain. We couldn't sustain a Sauropod today, but back then they were hugely successful. Seems like you just had way more food in general.
>>5164960>how long can such a big predatory animal even go without food and be in the same place for? Large body size improves how long you can fast. Small animals need to feed more frequently given similar metabolic constraints. I’ll bet many large theropods had no issue fasting for 90-180 days.
>>5167065They did since once the asteroid hit they all starved out while smaller mammals didn't. Even birds managed it.
