[Taxacom] Hedges /Kumar (eds) The Timetree of Life

[John Grehan]

Jason,

What a nice invitation! Thank you. I'll take that up with respect to
Steiper's chapter on primates. 

1. "Lemurs and lorises, collectively known as the strepsirrhines, are
united by the presence of a derived features including a toothcomb and
grooming claw."

Interesting assertion based on morphology. A 'toothcomb' is also
described for Tupaia (tree shrews) which certainly has the central keel
and margocristed (or lateral shelf) of tarsiers, lemurs and lorises. In
which case the toothcomb structure could be a primitive retention.
Lemurs and lorises do have a configuration where the lateral-most tooth
of the toothcomb is distinctly curved on the outer edge and the same
condition may apply to tarsiers.

Tarsiers also have a grooming claw.

2. :Tarsiers "...shared-derived morphological traits such as continuous
lip, link this linage with anthropoids (monkeys and apes)...(citing
Shoshoni et al 1996)."

 This is a little bit disingenuous as tarsiers have also been linked
with other prosimians through shared-derived morphological traits and
most such features linking tarsiers with anthropoids have been shown to
be erroneous (Schwartz, 2003),

3. "Extant anthropoids...have...complete postorbital closure."

I think some NW monkeys do not have complete closure (I'll have to check
on that).

4. "Platyrrhines have broad nostrils..." So do tarsiers (it's a
'primitive condition for primates, being general for other placentals as
well).

5. "the earliest stem anthropoid, Eosimias..."

An example of the highly problematic nature of the fossil record for
dating molecular phylogenies as there are problems as to whether
Eosimias is a primate let along an anthropoid:

Schwartz (2003) "Both [Eosimias] have tall and dominant trigonids on all
preserved lower molars...the non primate nature of the lower molars is
even more pronounced in E centennicus in which...the trigonid remains
large with fully expressed cusps...while the talonid becomes
buccolingually markedly narrower than the trigonid."

Schwartz (2003)"Isolated upper teeth refered to E centennicus are not
blatantly primatelike. The premolars and loar bear very tall, pointed
cusps, the buccal cusps of the molar are oriented distally away from the
protocone, and the distal side of the molar is deeply wasted."

"anteriorposteriorly abbreviated, dorsoventrally deep symphysis (Beard
et al. 1996). Would exclude New World monkeys with more primitive
symphyseal regions but include some prosimians would be more anthropoid
than Eosimias(Schwartz, 2003)

"large and projecting [lower] canines" (Beard et al 1996) also applies
to Eocene prosimians and lower anterior teeth of most anthropoids are
procumbent to some degree.

"lower M3 trigonid...appreciably wider than the talonid" (Beard et al
1996: 84). Characterizes all loer molars and therefore excludes this
taxon from primates (Schwartz, 2003).

"hypoconulid lobe on lower M3 reduced mesiodistally and buccolingually".
Restates previous features and no anthropoiiud or other primate has such
a truncated lower M3 talonid, although various tupaiids do (Schwartz,
2003)

"rounded, nonprojecting angular region providing expanded area for
insertion of pterygoid muscles (Beard et al 1996). Also applicable to
fossil and living indriiids, Adapis, lorisids, Hapalemur, Daubentonia,
plesiodapiforms Platychoerops, Chiromyoides, numerous preissodactyles
and artiodactyls (Schwartz, 2003)


I could go on with more, but maybe later.

John Grehan



-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Jason Mate
Sent: Monday, May 16, 2011 3:18 PM
To: Taxacom
Subject: Re: [Taxacom] Hedges /Kumar (eds) The Timetree of Life


John,

criticism is fair game as long as you back it up with facts. If you have
read any of the articles (i.e. Hepialids) point at the problems you see.
But deriding all books that use or rely on molecular data as propaganda
is just boring. You may have good points but you are just not fleshing
them out.

As for the use of fossil evidence, I have yet to come across a case were
they use them as maximal age when dating trees. It just makes no sense
to state that you have the fossil of the very first 
exemplar of a taxon.

Best

Jason

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