1) very difficult to identify species that are ancestral training but best shown which they existed
2) Agree if you measure “age” through the beginning of life to the current. However the chronilogical age of clades and lineages can also be measured from their beginning at a speciation occasion to the current, a more measure that is useful many circumstances
4) My point is the fact that the seafood branch is nearer to the beds base in comparison to some of the other terminal branches. Needless to say there’s two sister that is basal generally in most situations. The overriding point is that the foundation of this seafood branch lies during the foot of the tree, as well as for that good reason i would call it “basal”. That tree is simply too cartoonish and incomplete to essentially discuss relationships among vertebrate teams, but fishes are basal when you look at the sense just explained but rodents aren’t basal, because their beginning is someplace in the radiation that is mammalian well over the root of the vertebrate tree
If there have been 100 types of fish for the reason that tree (100 terminal seafood branches instead of just the only shown), you would not be calling seafood basal. This might be just our propensity to phone branches that are species-poor. This 1 branch that is long us into convinced that it really is unique. It’s not unique.
Santiago mentions the chronilogical age of a taxon, and makes use of this as being a reason for making use of the word basal. I wish to return and explain why i do believe they are unrelated problems.
Exactly exactly exactly How old is the fact that taxon? Then the age can be attached to three alternative time points: the time when this clade diverged from its closes relative (its root age), the time when it acquired its most distinctive derived trait (its apomorphy age), and the time when it began to diversify into the distinct lineages that we have today (its crown age) if it is a clade, which I would hope,.