Type of Speciation
The organisms in Chelicerata have undergone gradual speciation. Looking at fossils and the evolutionary history of the organisms, not much has changed over a long period of time. There have not been rapid time periods of new species and organisms. Their evolution has stayed gradual and consistent throughout history. Many of the organisms from millions of years ago in this taxonomy group, still resemble organisms alive today.
Type of Evolution
Divergent evolution has occurred in this taxonomic group. Looking at the structures and functions of the organisms it's apparent that they are all very similar but also have an abundance of differences. The group evolved from crab-like organisms millions of years ago but through separation of populations they have diverged from each other. Horseshoe crabs are most like their ancestors because they still live in and around the water and appear very similar to the first Chelicerata fossils found. Spiders, scorpions, ticks, and other similar organisms are terrestrial versions of their ancestors. They moved away from the water and diverged from each other becoming different species. They still share very similar external and internal characteristics with their ancestors and horseshoe crabs which is why they're in the same group.