The jumping frogs of Coconino County.Two paleontologists have discovered the oldest fossil frog to date, shedding new light on how these amphibians amphibian, in aviationamphibian, in aviation: see seaplane.amphibian, in zoologyamphibian, in zoology, cold-blooded vertebrate animal of the class Amphibia. There are three living orders of amphibians: the frogs and toads (order Anura, or Salientia), the salamanders and newts (order Urodela, or Caudata), and the caecilians, or limbless amphibians (order Apoda, or Gymnophiona), a little known evolved their jumping prowess. The new species, Prosalirus bitis Bitis /Bi·tis/ (bi´tis) a genus of venomous, brightly colored, thick-bodied, viperine snakes, possessing heart-shaped heads; including the puff adder (B. arientans), Gaboon viper (B. gabonica), and rhinoceros viper (B. nasicornis) ., hails from Coconino County, Arizona. Neil H. Shubin of the University of Pennsylvania in Philadelphia and Farish A. Jenkins Jr. of Harvard University describe the 190-million-year-old specimen in the Sept. 7 Nature.Unlike protofrogs from the earlier Triassic period Triassic period (trīăs`ĭk), first period of the Mesozoic era of geologic time (see Geologic Timescale, table) from 205 to 250 million years ago., this Prosalirus skeleton's pelvis is designed for transmitting the jumping force of the hind limbs to the rest of the body. The tail of its amphibian ancestors evolved into a short bone short bone (shôrt) n. that fits entirely inside the pelvis. A bone whose dimensions are approximately equal, consisting of a layer of cortical substance enclosing the spongy substance and marrow. The discovery of such an ancient frog in North America upends the idea that frogs first developed and diversified in the southern continents. According to Shubin, the ability to jump may have benefited the 5-centimeter-long Prosalirus by enabling it to escape the larger predators also preserved in the same rocks. |
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