I think one of the most identifiable and crucial characteristics of hominins is our bipedal locomotion, meaning our ability to walk on two legs. When we look at the human race with the knowledge that we are mammals and primates in the forefront of our minds, we are able to see a tremendous differentiation in the hominin species over time. The number of animals that have evolved to walk on their legs is so small, with only humans, gibbons, and large birds who walk upright with one foot at a time (yes, I looked it up). This ability to walk like this took millions of years since it occurred through evolution; a process we have learned about through studying fossils, as the lecture teaches. This ability, however, did not occur randomly. Instead, this evolution took place because this form of transportation allowed the individuals to travel faster, which helped them hunt more food. This ability to move quickly favored those individuals and allowed them to survive longer, leading to them mating and their favorable traits being passed on to their offspring. After millions of years of this genetic favoritism, the species developed to become completely bimodal, as we see the human species today. 

Another identifiable characteristic of hominins is our large brain. It was mentioned in the lectures that things like teeth and walking came long before the larger, more complex brain was developed in hominins. I have always felt that what makes humans the most different and outstanding than any other creature on the planet is our brain capability. This again does not happen quickly, it comes with millions of years in evolution. Those individuals whose brains were superior were able to live longer and mate more, hence why those genes were passed on overtime until everyone had it. 

The reason why these traits are so important to identifying the hominin species is because through studying fossils, we have been able to put together a timeline as to when (and where) certain characteristics of humans began to evolve. Because of paleontology, we know substantial pieces of the human timeline, including all the species that have come before and paved the way for the human species to fully evolve. Without fossils, we would have a very limited understanding as to what came before us. It is important to realize that the human species did not evolve over night, and even when primates began walking, they still were millions of years away from resembling the humans of today. However, we would not know any of this if it were no for finding fossils and scientists studying them, using reconstruction and other tests to picture what our path of evolution was like. 

Overall, understanding that evolution was not a matter of hundreds, or even thousands of years. It has taken millions of years for the human species to have the outstanding characteristics it has today. We know all of this from the study of fossils and using them as ways to imagine (in the most scientific way possible) what some primitive humans looked like and what the timeline from then to know is. I believe we are just scratching the surface as to how many fossils are out there and the myriad of things we can still learn from them.