Mammal

• The world's oldest known human fossil was discovered in 2006 in East Africa. The 3.3-million-year-old fossilized child was found in an area known as the Cradle of Humanity in North Ethiopia. The skeleton belongs to a primitive human species known as Australopithecus afarensis. The fossil is 100,000 years older and far more complete than "Lucy," an adult female of the same species discovered in the same area in 1974.
  
  

Sponge

• The oldest fossilized animals were found in 2010 on Australia's Flinders Ranges. The sponges date to about 640 million years ago, nearly 90 million years older than anything found previously. Sponges are primitive living animals that evolved long before life began to rapidly diversify 542 million years ago. The fossilized sponges were obtained by grounding down a fist-sized lump of rock by fractions of a millimeter and taking pictures of the exposed formations.
  
  

Insect

• The oldest fossilized whole-body impression of a flying insect was found in 2008 in the U.S. state of Massachusetts. The 300 million-year-old fossil was found in a shale and sandstone outcrop and would have lived during the second half of the Carboniferous Period, known as the Pennsylvanian Era. The impression measures about three inches, and the insect may be related to the common mayfly.
  
  

Amphibian

• The oldest fossilized amphibian was found in Late Devonian rocks at Scat Craig near Elgin, Scotland, U.K. Elginerpeton pancheni is the earliest known animal with four legs and dates back approximately 368 million years. The first fragment was found in the early 19th century. The next oldest amphibian, Ichthyostega, dates back about 363 million years and was found in Late Devonian deposits in Greenland.