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Re: More new articles
Senter's abstract contains some curious statements. Whilst crocs don't
possess a VN system they do have paired musk glands in the gular and
paracloacal regions that have a demonstrated role in chemical communication.
Paul Weldon who's done most work on these in crocs describes their role as
"secreting pheromones used in mating and nesting activities". They're
everted during several behavioural events, including fear, aggression and
courtship. The smell is often strong enough for a human to detect.
Chemically, they contain species, sex and even size-specific differences and
there's good experimental evidence that crocs can detect (and use) this
information from these secretions.
I checked with Paul and he confirmed that an animal doesn't need a VNO to
detect phermomones, and conversely having a VNO doesn't automatically imply
that pheromones are used. He did point out that most extant tetrapods do
have a VNO and while crocs don't (and birds probably don't either) there's
plenty of evidence that both use pheromones. Hence it makes no sense to
claim that a lack of a VN system in extinct archosaurs prevented them from
using chemical communication, whether pheromones or not.
I remember checking the script for Big Al and a similar conclusion was
reached (and not just by myself) - there are example of both extant
archosaur groups using pheromones, particularly during courtship, so it's
feasible that some dinosaurs did as well.
----- Original Message -----
From: "Aspidel" <firstname.lastname@example.org>
Sent: Sunday, November 10, 2002 7:24 PM
Subject: Re: More new articles
> Has this been studied for dinosaurs?
> In WWD, there's a scene where Big Al is attracted by the pheromons of a
> female. Could such a scene have been possible, or not?
> (I prefer not to draw scenes that never existed) -;)
> Cheers - Aspidel.
> From: <email@example.com>
> > Senter, P. 2002. Lack of a pheromonal sense in phytosaurs
> > and other archosaurs, and its implications for
> > reproductive communication. Paleobiology: 28 (4): 544-550
> > ABSTRACT
> > The vomeronasal (VN) system is a pheromone-processing
> > sensory system of tetrapods. Tetrapods use pheromones to
> > communicate territorial boundaries, reproductive status,
> > sex, and species identity. Presumed impressions of VN
> > bulbs on phytosaur frontals led to a claim that phytosaurs
> > possessed the VN system. However, in extant crocodilians,
> > which lack the VN system, the corresponding impressions
> > are associated not with cerebral tissue but with the
> > ophthalmic nerves. Phytosaur head morphology was not
> > conducive to pheromone collection. The extant phylogenetic
> > bracket suggests that all extinct archosaurs, including
> > phytosaurs, lacked the VN system. Without the pheromonal
> > sense, they would not have used chemical means to convey
> > territorial boundaries, reproductive status, sex, and
> > species identity. Instead, they would have used visual,
> > acoustic, and tactile cues, as in extant archosaurs and
> > other tetrapods in which the VN sense is reduced or absent.