Lower Eocene Crustacean Burrows (Israel) Reflect a Change from K- to r-Type Mode of Breeding Across the K-T Boundary Clarifying the Process of the End-Cretaceous Biological Crisis - Advances in Data, Methods, Models and Their Applications in Geoscience - page 314

of similar dimensions and wall sculpture. These common features attest to a similar body
structure. The main difference between these two burrow systems is the lack of brood
chambers during the Lower Eocene, which reflects a change in breeding strategy sometime
between the Campanian and the Early Eocene. Both burrow systems are in pelagic chalk
and thus external ecological factors turned the specially constructed brood chamber useless.
These local ecological changes were probably associated with the global biological turnover
at the K-T boundary. Their evaluation in comparison with other biological changes clarifies
the natural processes which resulted in the end-Cretaceous biological crisis.
Fig. 1. Road-cut exposing Taqiya Fm. greenish clay overlain by Mor Fm. chalk (M. Kitin
pointing at the fossiliferous bed).
Fig. 2. A. Location map. B. Columnar section of the Upper Paleocene-Lower Eocene
fossiliferous interval.