THE WEAPONS AND WINGS OF BIRDS. 



659 



METACARPUS OF SPUR-WINGED PLOVER, 

 BELONOPTERUS CHILENSIS. 



Cat. No. IS.Wti, U. .?. N. M. 



that birds long ago lost tlieir thumbs, and that the middle finger lias 

 come to do duty in its place. However, this digit has been termed thumb 

 for a long time, and since it is one by analogy, we will still call it so. 

 There is a curious instance among the gigantic extinct group of rep- 

 tiles, well named Dinosaurs,* where the thumb itself has become changed 

 in function, and instead of aiding the 

 other digits to lay hold of things, has 

 become transformed iuto a long, sharp 

 sjjike. This occurs in the Iguanodons 

 (fig. 5), and among them the species 

 particularly noticeable is I(juano<Jon 

 heruissartensis, one of nearly two score 

 that were haj)pily swept iuto a con- 

 venient Jurassic gully and there re- 

 mained for long ages, until brought to 

 light by the picks of the coal miners of 



Bernissart. That in this case the spike did duty as a weapon is a little 

 uncertain, and it may have served no more harmful purpose than that 

 of ripping oft" the husk of some fruit or vegetable which formed part of 

 the food of these great herbivorous reptiles. 



When these pointed thumb-spikes were first found, they were not 

 associated with the fore limbs, and so in restoring 

 the Iguanodon he was figured with the spike on 

 the end of his nose, something like a rhinoceros. 

 The late Dr. W. K. Parker, in a memoir on 

 the morphology of the duck and auk tribes, 

 rather hints that the thumb of Iguanodon and 

 the spur of Chauna chavaria are, morphologically, 

 not so far apart, t 



Another group of spur-winged birds is the 

 Jacamdfv, a family of small birds related to the 

 rails, having such long slender toes that they 

 run as easily over lily pads and tloating vegeta- 

 tion as other birds do over drv land. These little 

 birds, which are found in th6 warmer parts of 

 America, Africa, southern Asia, and Australia, 

 like the spur-winged plovers, have a spur on the 

 metacarpus, although it is not so large as in those 

 l)irds. As in the spur-winged i^lovers we find 

 si^urs associated with wattles for the African and 

 Asiatic species which have no wattles, have only 

 while the American species which have wattles 



FOREARM OF IGUANODON. 

 IGUANODON KERNISSARTEN- 



SIS. 



Rediiced. 



rudimentary spurs 



have well-developed spurs 



* Dollo, Note 8ur les Diuosaurieiis de Bernissart. 

 Beige., 1882-1884, 1. 1, PI. ix, t. ii, PI. viii. 



t The ^Morphology of the Duck aud Auk Tribes. 

 Roj-al Irish Academy. No. vi, pp., 55, 95. 



Bull. Mils. Rov. d'Hi.st. Nat. 



Cnnuiiigham Memoirs of the 



