[tomkinstinch]

A more detailed description is included in this publication from the author credited for the first photo:

http://www.ufrgs.br/paleotocas/Frank_et_al_2012.pdf

[ufo]

I'll take this opportunity to advertise one of my favourite science podcasts, Fronteiras da Ciência:

http://www.ufrgs.br/frontdaciencia/

It is in portuguese, but one of the older episodes from season 5 is a very fun and informative interview with prof Heinrich about these burrows.

[soneca]

Thanks for the recommendation! Added to my player