. Animals before man in North America; their lives and times. Paleontology. The Coming of Vertebrates and Rise of Fishes that of shark skin, and it is the teeth of these and other sharks that best illustrate the fact that teeth are really modifications of the skin and do not be- long in tlie same category as bones, intimately as the two are connect- ed in mammals. Many of the early sharks had the fins armed with a sharp, strong spine, and although fin spines have gone out of fashion among sharks, there are still a few species that preserve the fam- ily traditions, such as the Port Jackson shar
. Animals before man in North America; their lives and times. Paleontology. The Coming of Vertebrates and Rise of Fishes that of shark skin, and it is the teeth of these and other sharks that best illustrate the fact that teeth are really modifications of the skin and do not be- long in tlie same category as bones, intimately as the two are connect- ed in mammals. Many of the early sharks had the fins armed with a sharp, strong spine, and although fin spines have gone out of fashion among sharks, there are still a few species that preserve the fam- ily traditions, such as the Port Jackson shark, just referred to, or the more familiar spiny dogfish, which 107. Spine from the back fin of a Carbon- iferous shark, and one from the side fin of an Amazonian Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lucas, Frederic A. (Frederic Augustus), 1852-1929. New York, D. Appleton and company
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectpaleont, bookyear1902
