. Elements of geology : a text-book for colleges and for the general reader. Geology. 518 CEXOZOIC ERAâAGE OF MAMMALS. Fishes.âThe present relation between the three great orders of FishesâTeleosts, Ganoids, and Placoidsâwas first fairly established in the Tertiary. Teleosts were first introduced in the Creta- ceous, but only in the Tertiary did they become very abundant. Ganoids, on the contrary, became fewer in number; they sank into their present subordinate position. Among Placoids, the Hybodonts are gone, the Cestra- cionts are few in number, but the Squalodonts reach their. Figs. 884-888
. Elements of geology : a text-book for colleges and for the general reader. Geology. 518 CEXOZOIC ERAâAGE OF MAMMALS. Fishes.âThe present relation between the three great orders of FishesâTeleosts, Ganoids, and Placoidsâwas first fairly established in the Tertiary. Teleosts were first introduced in the Creta- ceous, but only in the Tertiary did they become very abundant. Ganoids, on the contrary, became fewer in number; they sank into their present subordinate position. Among Placoids, the Hybodonts are gone, the Cestra- cionts are few in number, but the Squalodonts reach their. Figs. 884-888.âTertrart Fisiies- primigenius (after Agassiz). £ megalodon, x \ (after Gibbes). Fig. 888. â Placoids: 884. Lamna elegans (after Agassiz). 885. Notidanus S6. Carcharodon augnstidens (after Giblbes). 887. Carcharodor. Teleost: 888. Clupea alta (after Leidy). maximum development, both in number and size. In the marine Ter- tiary of the Atlantic border, both Eocene and Miocene, sharks' teeth are found in immense numbers, and of very great size. Some of the triangular teeth of the Carcliarodon megalodon (Fig. 887) are found six and a half inches long and six inches broad at the base. The own-. 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 LeConte, Joseph, 1823-1901. New York : D. Appleton and Co.
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