The impression that I got from the article is that we don't know yet, because the experts have not heard of this before either. It sounds like scientific study

The impression that I got from the article is that we don't know yet, because the experts have not heard of this before either. It sounds like scientific study only goes back maybe a decade, it's been largely confined to Brazil, and the scientists involved are geologists, not paleobiologists. So is it for real? It sounds both crazy and plausible to me at the same time. I think it's too soon for us laypeople to draw any conclusions. I'm reasonably certain this is not an April Fool's joke. Here's an article in a Brazilian newspaper from 2015 (via Google Translate): https://translate.google.com/translate?hl=en&sl=pt&u=http://oglobo.globo.com/sociedade/caverna-escavada-por-mamiferos-gigantes-descoberta-na-amazonia-17032201&prev=search https://translate.google.com/translate?hl=en&sl=pt&u=http://...