Characteristics

Behavior

http://www.livescience.com/52361-turtle-facts.html
Habitat

https://www.researchgate.net/publication/259205934_Primary_fibroblast_cultures_and_karyotype_analysis_for_the_olive_ridley_sea_turtle_Lepidochelys_olivacea

Loggerhead Turtle
http://biostor.org/reference/106942/page/2

These karyotypes show that the size and shape of the chromosomes (with the exception of a couple) are relatively the same size. This means that these two species are related because their DNA is the same for some of the chromosomes. Specific chromosomes code for specific traits. For example, all turtles have a gene in their DNA which codes for a shell. They also have a gene that codes for no teeth, but great hearing. The minor differences in create some traits that creates new species.
 

http://www.tutorvista.com/content/biology/biology-iii/cell-reproduction/karyotype.php
When we compare a turtle to a human karyotype there are many differences. Some minor similar DNA that contains traits can be traced back to find a common ancestor. Also these two organism have different sex chromosomes. For example, heat can effect the gender of a turtle. Since many of the chromosomes are different, it mean that their DNA is different and if they do not contain the same DNA, they are not related because different DNA codes for different traits and proteins. 

 PhylogeneticTree
Three is showing that horns appeared in the species from Stephanospondylus to Meiolania, however in between these two groups the Anthodon and Deltavjatia did not have horns. It also shows that Meiolania, Proganochelys, Trionyx, Kayentachelys, Chelonia, Macrochelys temmincki, Terrapene carolina, pelomedusa, and Faxemys are toothless. Lastly, Odontochelys, Trionyx, Chelonia, Macrochelys temmincki, Terrapene carolina, pelomedusa, and Faxemys are invagination. This means that they are able to fold up into themselves. This also shows that Bolosaurus and Belebey do not contain any of these traits.
https://pterosaurheresies.wordpress.com/tag/evolution-of-turtles/

https://schoolworkhelper.net/kingdom-animalia-general-characteristics-of-animals/This diagrams able to show us that all three types of turtles are related until the testudines order. This diagram also tells us that neither two are more similar than another, meaning that two of the three turtles have the same family meaning they are more related. Since the turtles are lastly related at their order it means that they are not very closely related. As they move down to family, genus, and species they become even more different. We also know that 

Behavioral characteristics- 

Snapping Turtlehttp://www.scienceiq.com/Facts/HowDoesTheTurtleGetItsShell.cfm

These two diagrams are able to show relatedness because an embryo development is at the very beginning. If they develop very similarly, chances are that they are related. Both diagrams also show a shell outline, this shows the tatty are related because they have adapted to grow a shell at a very early stage in life. Lastly, these two diagrams show a similar head shape This shows that they are related because they have to eat and survive, but also that since their head shape is so similar they have to have had a very close ancestor in the near past. 

http://my.kwic.com/~pagodavista/schoolhouse/species/herps/turtneck.htm