Darwin himself stated that:” If no transitional animals
are found, his theory is not valid”.
And there exist many transitional animals, most of which are extinct. They did the job of surviving and reproducing better than their precursors and thus made their precursors extinct. And follow on creatures did the same to them. It would be illogical to expect many precursor animals to still be living.
Good thing that there have been lots of transitionals found, eh?
This is a nice example of a transitional. Note its position in the chart which follows (hint--in the right center):
Site: Koobi Fora (Upper KBS tuff, area 104), Lake Turkana, Kenya (4, 1)
Discovered By: B. Ngeneo, 1975 (1)
Estimated Age of Fossil: 1.75 mya * determined by Stratigraphic, faunal, paleomagnetic & radiometric data (1, 4)
Species Name: Homo ergaster (1, 7, 8), Homo erectus (3, 4, 7), Homo erectus ergaster (25)
Gender: Female (species presumed to be sexually dimorphic) (1, 8)
Cranial Capacity: 850 cc (1, 3, 4)
Information: Tools found in same layer (8, 9). Found with KNM-ER 406 A. boisei (effectively eliminating single species hypothesis) (1)
Interpretation: Adult (based on cranial sutures, molar eruption and dental wear) (1)
See original source for notes:
Source: http://www.mos.org/evolution/fossils/fossilview.php?fid=33
One more time for those in the back row: