Each segment has the same sets of organs and, in most polychaetes, has a pair of parapodia that many species use for locomotion. Septa separate the segments of many species, but are poorly defined or absent in others, and Echiura and Sipuncula show no obvious signs of segmentation.ach segment has the same sets of organs and, in most polychaetes, has a pair of parapodia that many species use for locomotion. Septa separate the segments of many species, but are poorly defined or absent in others, and Echiura and Sipuncula show no obvious signs of segmentation.
Chicxulub is most famous for being near the geographic center of the Chicxulub crater, an impact crater discovered by geologists on the YucatÃ¡n Peninsula and extending into the ocean. It was created by the impact some 65 million years ago of the Chicxulub impactor, an asteroid or comet which caused the CretaceousâPaleogene extinction event, which led to the demise of the dinosaurs.
Located 112 miles (180 km) west of Cancun, Chichen Itza is the most famous of all the Mayan ruins. This is somewhat ironic because it most well known structures do not have a typical Classic Mayan architecture but show influences from Central Mexico.ocated 112 miles (180 km) west of Cancun, Chichen Itza is the most famous of all the Mayan ruins. This is somewhat ironic because it most well known structures do not have a typical Classic Mayan architecture but show influences from Central Mexico.