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.
[el kas'tiÊo]), Spanish for the castle), also known as the Temple of Kukulcan, is a Mesoamerican step-pyramid that dominates the center of the Chichen Itza archaeological site in the Mexican state of Yucatan. yucatÃ¡nesearchers concluded that there must be an inner pyramid approximately 33 m (108 ft) wide, shaped similarly to the outer pyramid, with 9 steps and a height of 17 m (56 ft) up to the platform of the temple where the Chac Mool and the jaguar were found.