Vertebrates come in all shapes and sizes, which means that vertebrate  fossils can be found in all shapes and sizes, and some have their own  specific field of study.  One such specific field is that of  anthropology.  It is this field that has experienced popularity and  notoriety.  Magazines and television programs, especially specialized  educational channels, have contributed to making this such a popular  field.   Jane Goodall, along with Louis, Mary and Richard Leakey, are  among those who have received notoriety through their appearances in  magazines and on television.

 

Australopithecus afarensis existed between 3.9 and 3.0 million years ago.  Afarensis had an ape like face with a low forehead, a bony ridge over the eyes, a flat nose, and no chin. Afarensis also had protruding jaws with large molar teeth.  The cranial capacity varied from about 375 to 550 cc.  Except for the more human like teeth, the skull is similar to that of the chimpanzee.  The canine teeth are much smaller than those of modern apes, but larger and more pointed than those of humans, and the shape of the jaw is between the rectangular shape of apes and the parabolic shape of humans.  However, their pelvis and leg bones more closely resemble those of modern humans, leaving little doubt that they were bipedal.  Afarensis had a brain capacity that varying between 380 - 450 cc.  Their bones show that they were very strong physically.  Heights varied between about 107 cm (3½ feet) and 152 cm (5 feet).  Males and females show a considerable difference in size, varying from 1 - 1.7 m in height and from 25 - 50 kg in weight.  This is a condition known as sexual dimorphism, and in this case, females were substantially smaller than males. The finger and toe bones are curved and proportionally longer than in humans, but the hands are similar to humans in most other aspects.  Most scientists consider this as evidence that afarensis was still partially adapted to climbing in trees, while others consider it just an evolutionary remnant.  
 

   

It has long been accepted that Archaeopteryx was a transitional form between reptiles and birds.  Lately, scientists have realized that it even has more of a resemblance to its possible ancestors, the Maniraptora, than to modern birds.  Is Archaeopteryx an earlier ancestor to modern birds and related to dinosaurs?  The debate still continues, since there have been no fossil discoveries to date showing evolutionary examples between dinosaurs and Archaeopteryx.  One study, based on the belief that animals sharing a common ancestry exhibit common features during embryonic formation, found a surprising result.  If birds are related to dinosaurs, there should be evidence in bird embryos of a thumb remnant, as dinosaurs had such.  However, in the microscopic examinations of the stages of development in the embryos of birds, the embryos showed no vestige of a thumb that is present in primitive form in dinosaur fossils.  Yet there are dinosaurs that had wishbones, three toed feet and cranial air sacks, all distinctive bird-like features.   It is now thought that even pterosaurs had hollow bones, yet one more characteristic similar to birds.