Days were shorter in time of the dinosaurs, according to recent AMGC paper in Paleoceanography and Paleoclimatology

These extinct mollusk Torreites sanchezi known as rudist clams were abundant and diversified in the Cretaceous and their shells show abundant growth rings. The new study direct by Dr. Niels de Winter, published  in the well-known Paleoceanography and Paleoclimatology journal used laser ablation ICPMS to analyse their shells at high resolution (down to subdaily) and count the layers to understand rudist life and how water conditions changed in the Cretaceous. The work reveals that a day in the Cretaceous was shorter lasting only 23:30 hours compared to today, this implies that the Earth rotated faster, roughly 372 times a year. The study also demonstrates that most likely rudist lived in symbiosis with photosynthetic algae, just like modern corals. 

More details in the AGU News Room press release

Worldwide press coverage reported these results, Newsweek, Der Spiegel, Knack, Science Daily etc. (Altmetric)

Read some poetry about it https://thepoetryofscience.scienceblog.com/1167/ancient-rings-of-time/