Complex sentence: However in one recorded case, the egg incubation occurred entirely withing a chicken and even the chick hatched inside and emerged from its mother without the shell, leading to internal wounds that led to the death of the mother hen.
Split into simpler sentences: However in one recorded case, the egg incubation occurred entirely within a chicken. The chick hatched inside and emerged from its mother without the shell, leading to internal wounds that killed the mother hen.