Scientists Found 520-Million-Year Old Trilobite Eggs In New York With Sex Organs On Their Heads By Ankan sarkar | Feb 24, 2017 05:13 PM EST Researchers discovered the eggs of hard-shelled creatures from the upstate New York. This creature is known as Trilobite and it has existed more than 520 million years ago. Their existence was wiped out almost 250 million years ago during the end of the Permian period. A group of scientists led by Thomas A. Hegna found preserved trilobite eggs from the Lorraine Group in upstate New York, USA. Trilobites are one of the earliest known groups of arthropods. This is the first time in history scientists found unambiguously preserved eggs and genitalia of trilobites. Their findings were first published in the journal of Geology. Trilobites used to store their eggs at the back of their heads. Same thing could be found in female horseshoe crabs, they release their unfertilized eggs from an ovarian network connected with their heads. Scientists described over 20,000 species of trilobites till date. These extreme variations make them the most diverse class of extinct organisms in the world. As per the report of Mail Online, the smallest known trilobite species was less than a millimeter long, while the largest species was more than one feet long. Some species was about two feet long. The extinction of trilobite was one of the Earth's five greatest mass extinction events. Those mass extinctions also affected the ecological balance, as researchers assumed. The eggs inside the fossils that Hegna and his colleagues found in New York were spherical in shape and the diameter was not more than 200 micrometer(µm). The species of trilobite fossils that researchers found was named as Triarthrus Eatoni. This species belongs to the Lorraine family that used to roam around northeastern US and Canada. The genital pore was located at the back of their head from where they used to eject their eggs and sperm. Although, 97 percent of fossil records were expired forever and rest of the skeletons were cast at pyrite. Under perfect geological conditions, Pyrite is the best material to fossilize any creatures, it is a hard mineral containing iron.