As an adaptation to new and changing climate conditions, the evolution of Bipedal Apes occurred. Temperatures dropped, thus changing the environment as well as food and habit resource availability. As a result, hominids evolved locomotion features that allowed them to adapt to the new conditions. With far less trees to climb and more ground to cover, hominids needed to be able to travel distances. Bipedal features include standing upright, walking on two feet (instead of all four), and the anterior location of the foramen magnum being underneath the head instead of behind – which gives support for a body standing upright rather than a body behind the head on all fours. Another trait characterizing a hominin would be the size and shape of our teeth, as well as crests attachments for muscles used to chew food. Our front teeth are small while large premolars and molars in the back to crush and grind our teeth to help process food. Over time are dental anatomy has evolved and developed to more specialized diets – we eat meat and we need to be able to break down our food before further digestion, while species with less-specialized teeth have a very diverse diet and large incisors to assist. Today, we use our teeth to eat just about anything, but evolution shows the shape and size of our teeth did evolve to be able to chew food like meat. Our brain size also greatly defines a hominin from other species in that it is relatively larger than our chimp ancestors. Our frontal lobes develop large cerebrums to hold more sensory information, and with large brains comes a high expense. To accommodate one must be able to eat enough calories to sustain enough energy. This means we needed to become better at acquiring food (as well as other natural resources) and eat more efficient meals. A “leaves and fruit” diet wouldn’t produce enough calories to accommodate our large brains – nor would depleting all of our energy trying to gather the amount that would- especially if we have not yet evolved to travel distances. This helps explain why most non-bipedal apes have small brains, live off mostly fruit and leaf diet, and hang out in trees- hence their (varied) non-bipedal structures, presence of tails, and a grasping big toe. These are all characteristics that can be observed evolving at stages overtime, known as Mosaic Evolution, with a wide variation and distribution range. We adapt to the climate and the environment in which we reside and that can been studied as far back as 7 million years ago. Fossilized skeletal remains of hominids show basic from of transition in both primitive and derived characteristics. We can study these remains, along with other fossils in the area to put together a general concept of how a species lived and what their environment was like. Index fossils can provide cues on identifying strata in different areas dating to the same time period. Using biostratigraphy, anthropologists provide an overall understanding of our evolution and aids in reconstructing the past to give as accurate an explanation as possible. It is not always complete, and relies on the Principle of Superposition to obtain this data from layers in sediments. But nonconformities are common and putting the entire picture together may not always be possible. This is why carbon dating is so important, because it does provide an exact time in history for us, which we can then use this information and it compare fossilized specimens to reconstruct a prehistoric environment – a study known as Paleoecology. This provides clarity to the bigger picture, whether or not plants and animals were present, what kind were, what resources were available, and this all helps fill the holes in our evolutionary history to understand who we are today.