DINOSAURS 163 
Jo 
evidence. But nearly a quarter of a century elapsed before it was 
forthcoming. In the years 1841 and 1848 portions of the lower 
jaw with some attached teeth were found. It is very interesting 
in the light of recent discoveries to read the conclusions arrived 
at by Mantell and Owen, with regard to the organisation of this 
great Wealden reptile, and to see how, with the exception of 
certain details, they have been confirmed. Considering the 
imperfect nature of the materials at their command, it is 
wonderful that their forecasts should have turned out so 
successful. Thus Professor Owen predicted for the Iguanodon 
a total length of twenty-eight feet, and specimens discovered of 
late years show a length of twenty-four feet. 
Dr. Mantell also was the first to prove, from the nature of the 
Wealden strata, that they were deposited in or near the estuary 
of a mighty river. With regard to the aspect of the country in 
which the Iguanodon flourished, he showed that coniferous trees 
probably clothed its Alpine regions; palms and arborescent ferns, 
and cycadaceous plants (7.e. plants resembling the modern zamia 
or “false palm”) constituted the groves and forests of its plains 
and valleys; and in its fens and marshes the equisetacea (mare’s 
tails) and plants of a like nature prevailed. Since the days 
of Dr. Mantell, the remains of Iguanodon or other closely 
allied genera have been found on the Continent, in England, and 
North America, in strata of various ages, from the Trias or 
New Red Sandstone to the Chalk (see Table of Strata, 
Appendix I.). The American Hadrosaurus must have been 
an allied form. 
In the year 1878 was announced one of the most fortunate 
discoveries known in the whole history of geological science— 
a discovery unique of its kind, and one which throws considerable 
light on the nature of the monster first discovered by Dr. Mantell. 
