Longitudinal fissure Longitudinal fissure The longitudinal fissure (or cerebral fissure, median longitudinal fissure, or interhemispheric fissure) is the deep groove that separates the two hemispheres of the vertebrate brain. The medial surfaces of the two hemispheres are as similarly convoluted by gyri and sulci as is the outer surface of the brain. It is thought that a majority of existing animals, including Homo sapiens, have evolved from a common wormlike ancestor that lived around 600 million years ago, called the urbilaterian. A bilaterian animal is one that has symmetrical left and right body halves. While it is still debated whether this species
Red Hills Fissure Pleistocene. The abundant fossil remains of the Jamaican Coney ("Geocapromys brownii") found there have enabled the construction of a life table for that species. Analysis of fluorine uptake in the fossil bone has allowed the time-span of the deposit to be dated to about 25–40 thousand years ago. Fossil remains of the extinct Jamaican flightless ibis ("Xenicibis xympithecus") have also been found there. Red Hills Fissure Red Hills Fissure is a palaeontological site at the Red Hills in Saint Andrew Parish of south-eastern Jamaica. The Red Hills Fissure is a karstic solutional feature, with a vertical extent of about 8