Though “doctors disagree” thus in regard to the scientific classification of this small group of animals, this fact does not in the least diminish the intense interest in the individual members of the order.
Ancestry
Although the huge dragon-like dinosaurs or “terrible reptiles,” some of which were probably more than one hundred feet long, became extinct during the Mesozoic epoch, perhaps millions of years before man made his appearance upon earth, we have one group of reptiles still living in certain parts of the earth of which the Mesozoic lords of creation need not feel ashamed. While most of the living Crocodilia are mere pigmies in size, compared to the Atlantosaurus, there are a few representatives of the living group, to be discussed later, that are said to reach a length of thirty feet, which length makes pigmies, in turn, of most of the other living reptiles.
Considering the extinct as well as the living Crocodilia, Gadow says it is very difficult to separate them from the Dinosauria. In the Mesozoic Crocodilia the fore limbs were much shorter and weaker than the hind limbs, as was often the case with the dinosaurs; they were almost entirely marine, but gave indications of descent from terrestrial forms.
Various facts point, thinks Gadow, “to some Theropodous Dinosaurian stock of which the Crocodilia may well form an aquatic, further developed branch” (Cambridge Natural History, p. 432).
Skull of Belodon. A, from above; B, from below. A, orbit; Bo, basi-occipital; Ch, internal nares; D, pre-orbital fossa; Exo. exoccipital; Fr. frontal; Ju. jugal; La. lacrymal; Mx. maxilla; Na. nasal; Pa. parietal; Pl. palatine; Pmx. pre-maxilla; Por. post-orbital; Prf. pre-frontal; Pt. pterygoid; Qu. quadrate; S, lateral temporal fossa; S′, superior temporal fossa; Sq. squamosal; Vo. vomer. (From Zittel.)
Fig. A. A Triassic Ancestor of the Crocodilia.
From Parker & Haswell, Textbook of Zoölogy.
The direct ancestors of the Crocodilia, Gadow says, are still unknown.