84 FOURTH FLOOR, SOUTHEAST PAVILION 
In the Tower of the Southeast Pavilion are displayed the fossil fishes 
which belong to a much earlier period than the mammals and reptiles, 
: some of them having lived twenty to fifty millions of years 
Fossil : am : fc ae 
Fishes ago. Many of these forerunners of backboned animals are 
quite unlike any living fishes and are probably only very 
indirectly related to them; some were small, curiously encased in shells; 
others, shown in the three cases in front of the visitor, attained large size 
and were evidently formidable creatures. One of them in fact, Dinichthys, 
shown in the middle of the gallery, was probably among the most destructive 
creatures that ever lived in the sea. Its Jaws were so strong that it could 
crush a plate of bene as thick as one’s hand. Such an actual specimen, 
fractured in life and showing the marks of “teeth” is shown in a neighbor- 
ing case. 
The collection is so arranged that he who makes the tour can see the 
principal kinds of fessil fishes and is able, in a measure, to outline the history 
and pedigree of the entire group. He can trace the rise and fall of the 
carly plate-covered fishes; the era of the sharks which on the one hand 
supplanted the earliest fishes and were in time replaced by the more efficient 
lungfishes and ganoids; the age of ganoids when the waters were filled with 
these enamel-scaled fishes; finally the age of the bony-fishes, or teleosts, 
the multitudinous forms of to-day, the herrings, cods, perches, whose 
methods of swimming, feeding and breeding are far more efficient than 
those of any of their predecessors. 
Above the entrance are the jaws (models), spreading nine feet, of a 
huge fossil shark in which the actual teeth are arranged as in 
Jaws of the sharks of to-day, in the usual banks or rows — the teeth 
Huge Fossil . ; : ; 
ine in the hinder rows having served to replace those in front. 
Such a shark probably measured from seventy to ninety feet 
and its race may well have become extinct, when for various reasons the 
enormous volume of food necessary to support it could not be maintained 
within its range of sea. 
In the first aleove to the left, by the window, is a “fossil 
Fossil 
Aauvarivim aquarium”? in which a number of models of these earliest 
fishes are arranged in a group, as though alive in the sea. 
In the next alcove are the early fossil sharks which superseded the tribe 
of plated fishes just mentioned. These sharks had soft skeletons, simple 
fins and a number of other primitive features which lead to 
ginoaines the belief that all of the higher fishes, and the higher backs 
boned animals therefore as well, were descended from them, their simpler 
structures beceming more complicated in many directions. In one of the 
early sharks here exhibited, soft parts such as muscles and gill filaments, 
have been petrified. 

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