[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
RE: Turtles and Crocodylians are not Reptiles - no? What are they?
Robert Takata wrote:
> As Pharris and Keesey noted, *closer* in a phylogenetical/hennigian
> context: shared the same evolutionary history for a longer time.
I'm still confused by this, because I would never have equated the term
"closer" with "shared the same evolutionary history for a longer time." Even
in a phylogenetic/Hennigian context.
For example... Say a phylogeny recovers _Eoraptor_ and _Herrerasaurus_ at the
base of the Theropoda, with _Eoraptor_ and _Herrarasaurus_ as successive
outgroups to the clade that includes all other theropods (Neotheropoda).
_Herrerasaurus_ is therefore the sister taxon to Neotheropoda. _Velociraptor_
is a neotheropod. Thus, _Herrerasaurus_ and _Velociraptor_ form a clade to the
exclusion of _Eoraptor_. In other words, _Herrerasaurus_ and _Velociraptor_
share the same evolutionary history for a longer time than _Eoraptor_ and
However, I would *not* say that _Herrerasaurus_ is "closer" to _Velociraptor_
than it is to _Eoraptor_. I would say _Herrerasaurus_ is closer to _Eoraptor_.
This is because _Eoraptor_ and _Herrerasaurus_ are relatively closer on the
phylogenetic tree. The topology shows only one node separating the two. Many
more nodes separate _Herrerasaurus_ from _Velociraptor_ (Ceratosauria,
Megalosauroidea, Allosauroidea, Ornitholestidae, Tyrannosauroidea,
I'm not trying to be tricky here with semantics - quite the opposite. I'm
just trying to get the point across that "closer" in a phylogenetic context
does *not* necessarily mean "shared ancestry". Further, "closer" should not
even imply "shared ancestry".
Use video conversation to talk face-to-face with Windows Live Messenger.