paleonet Palaeobiogeographic monograph reviewed by Art Boucot

[John.Laurie@xxxxxxxxxxx]

Review taken from The Australian Geologist 120, 22-23 (by permission of
editor and author)

Palaeobiogeography of Australasian faunas and floras
Edited by A.J. Wright, J.A. Talent, G.C. Young & J. Laurie. (2000)
Association of Australasian Palaeontologists, Memoir 23, 515 pp. ISSN
0810-8889. Obtainable from the Geological Society of Australia, Suite 706,
301 George Street, Sydney, NSW 2000, Australia. Price $A81.95 incl. GST for
orders within Australia; $A84.50 for overseas orders (both include surface
postage).

Reviewed by Art Boucot, Department of Zoology, Oregon State University

	This is a most valuable volume for anyone concerned with Phanerozoic
biogeography. It also summarizes in readily available form a truly
monumental mass of taxonomic and biostratigraphic information for the
Australian Phanerozoic, plus adjacent regions with emphasis on New Zealand,
covering animal and plant groups, marine and nonmarine, vertebrate and
invertebrate, complete with extensive references. The only significant
omission is the Triassic, for which one hopes that the "delayed" item will
be brought to rapid completion and publication. Ninety authors took part in
the project, with multiauthored chapters for every period except the
Permian, which resulted in contributions from informed specialists for
almost all of the biotic groups considered.
A welcome feature is the emphasis on data as contrasted with speculation.
The complexities of local stratigraphic nomenclature are handled in a manner
making understanding by the reader very easy both through geological time
and geographically; one does not get bogged down in a mass of nomenclature.
The authors have gone to great trouble to provide tabular and appendix
presentations that make the material readily accessible to the outsider,
whether a concerned specialist or generalist. Succinct summaries and
conclusions are provided for the data at several levels from the individual
biotic group in each time interval up to the overall biogeographic picture
during each geological period.
	The overall layout of the book is excellent, as is the quality of
reproduction, and the price is very moderate in these times of three figure
costs for all too many books. There are very, very few printer's errors (I
noted none of any consequence).
	The overall arrangement is by geological period beginning with the
Cambrian. Following introductory materials that cover such things as
paleogeographies that have been proposed for the time and summaries of the
available "absolute" age data, come sections dealing with the available
animal and plant groups, each one prepared by a qualified specialist,
followed by comprehensive biogeographic summaries. 
	The volume forcefully makes the point that the relatively complex,
well-grounded biogeographies of the Cenozoic are almost an order of
magnitude more reliable than those of the pre-Cenozoic, the Paleozoic being
most speculative. This comment applies as well to ocean surface current
reconstructions and accompanying paleogeographies. We have essentially no
understanding about the location of oceanic gateways in time or space for
the Paleozoic. Paleozoic biogeographies require that there have been
barriers of one kind or another to reproductive communication, resulting in
reproductive isolation leading to endemism, but locations remain essentially
unspecified and highly speculative. All of this indicates the need for more
detailed, reliable paleogeographies for the older time intervals, without
which our understanding of the overall biogeographic picture suffers.
	In principle biogeographic analysis should include every group of
organisms present in the time interval under consideration being critically
considered by well informed specialists. However, in practice this is never
the case for the following reasons: 1) some groups are of such scattered
occurrence and are so rare as to provide limited biogeographic data,
Paleozoic echinoids being an example; 2) many groups although numerically
abundant in appropriate environments have not been carefully collected or
studied in many parts of the world, Paleozoic echinoderms and ostracodes
being good examples; 3) during every time interval, Cambrian to present,
well informed specialists have been overly attracted to certain groups while
leaving other groups relatively unstudied, with molluscs being favored in
the post-Triassic as contrasted with brachiopods and trilobites in the
Paleozoic. Consideration of this volume indicates that trilobites are the
favored group for biogeographic analysis in the Cambrian and Early
Ordovician, trilobites and brachiopods in the later Ordovician, brachiopods
in the post-Ordovician Paleozoic, and ammonoids together with bivalves and
gastropods in the Jurassic and Cretaceous, with bivalves and gastropods
dominating the Cenozoic story. Beginning with the Carboniferous foraminifera
are of great utility for biogeographic purposes, with the benthics
dominating this field. Australian biogeographic practice in this volume
conforms to practice elsewhere. All of this reflects the relative abundances
of some groups as contrasted with others (eurypterids will presumably never
be of much utility in Paleozoic biogeography), and the attention devoted to
some groups as contrasted with others. It is notable that among the
palynomorphs there is very helpful biogeographic information from higher
land plant pollen and spores in the Cenozoic, helpful information within the
Jurassic and Cretaceous, but far more limited data for the Paleozoic. The
palynomorph situation presumably reflects economic utility as much as
anything. The overall scanty data for chitinozoans and acritarchs is a gap
that needs to be filled. Vertebrates in the Paleozoic are relatively rare,
which results in their biogeographic utility being reduced to considering
the global distributions available from a very small data set; the situation
in much of the Mesozoic is better, whereas that in the Cenozoic is
considerably better. Higher land plant biogeography is of limited utility at
present for the Devonian (Silurian localities are too uncommon globally to
be useful), but of far more value in the Carboniferous and younger strata,
with the chief limitation being the small number of paleobotanists available
to study the varied floras.
	Perhaps the most telling point driven home by this book is the
overall lack of the necessary taxonomic work on group after group of
fossils. This problem could be easily pointed out for most parts of the
world, i.e., its not just an antipodean headache, The book makes it very
clear that reliable biogeography depends on reliable taxonomy and
biostratigraphy, without which there is confusion. One wishes that
administrators in responsible positions would take the trouble to read
enough of this treatment to understand how much basic taxonomy and
biostratigraphy remains undone, again not just in the Antipodes. For
organismal group after group there is the unwelcome note that inadequate
data are currently available with which to arrive at reliable biogeographic
conclusions, although this comment is in no way intended to downplay the
monumental effort that has gone into the descriptions of the groups
discussed. It is also made clear that for all too many time intervals too
few and inadequate fossil localities are known, i.e., a lot more effort
needs to be put into the geological mapping that commonly turns up new
localities, as well as having individual specialists spend more time in the
field trying to uncover "missing" biotas from time intervals of concern.
	Finally, this is an excellent treatment of the topic that deserves
to be copied in other parts of the world; it sets a new and higher standard
for Phanerozoic biogeography. It is time to follow this new route rather
than continue the printing of volumes that deal in a hit or miss way with
this or that group of organisms through this or that time interval to
achieve a pot-pourri that leaves the reader wondering what is left undone.

posted by J. Laurie, AGSO, Canberra