Page 400 - Introduction to Paleobiology and The Fossil Record

ECDYSOZOA: ARTHROPODS 387

The Late Carboniferous Mazon Creek fauna of Illinois occurs across two facies associated with
a deltaic system. The marine, Essex fauna developed on the delta front and is dominated by fi shes,
including coelacanths and some of the earliest lampreys. However, huge crustaceans are found
together with the weird Tullimonstrum whose affinities are uncertain but might be a heteropod gas-

tropod. The non-marine Braidwood assemblage is a diverse array of arthropods including 140 species
of insects together with centipedes, millipedes, scorpions and spider-like arachnids. The fauna,
together with a flora of over 300 species of land plant, occupied a lowland swamp milieu between

the sea and coal forests. Shrimps and ostracodes apparently inhabited ponds within the swamps.
More recent terrestrial assemblages such as the Montsech fauna from the Lower Cretaceous of
northeast Spain have yielded new information on the evolution of spiders. Paul Selden (University
of Kansas) has described three web-weaving species equipped to attack an abundant insect life
inhabiting settings around coastal lagoons.
It is clear from these extraordinarily well-preserved faunas that numerous ancient communities,
marine and non-marine, were dominated by arthropods, just as today.

Clarkson, E.N.K. 1998. Invertebrate Palaeontology and
Review questions Evolution, 4th edn. Chapman and Hall, London.
(An excellent, more advanced text; clearly written
1 The spectacular arthropod faunas of and well illustrated.)
Burgess, Chengjiang and Sirius Passet Fortey, R. 2000. Trilobite: Eyewitness to Evolution.
suggest an early diversifi cation of these HarperCollins Publishers, London. (Fascinating per-
ecdysozoan taxa. Was this really evolu- sonal voyage of discovery.)
tion’s “big bang” or are these arthropods Gould, S.J. 1989. Wonderful Life. The Burgess Shale
just too weird to comprehend when com- and the Nature of History. Hutchinson Radius,
pared to modern faunas? London. (Inspirational analysis of evolution’s “big
2 Trilobites were an integral part of the bang”.)
Paleozoic fauna for over 200 million years Robison, R.A. & Kaesler, R.L. 1987. Phylum Arthrop-
yet they finally became extinct at the end oda. In Boardman, R.S., Cheetham, A.H. & Rowell,

of the Permian. What sorts of animals A.J. (eds) Fossil Invertebrates. Blackwell Scientifi c

filled their niches in the Modern evolu- Publications, Oxford, UK, pp. 205–69. (A compre-
hensive, more advanced text with emphasis on tax-
tionary fauna? onomy; extravagantly illustrated.)
3 Trilobites have featured in a number of Whittington, H.B. 1985. The Burgess Shale. Yale Uni-
evolutionary schemes, some showing versity Press, New Haven, NJ. (Classic description
gradualistic trends and others showing of the Burgess Shale and its fauna.)
punctuated trends. Are these different
patterns correlated with different groups
of trilobite or perhaps to their life References
environments? Armstrong, H.A. & Brasier, M.D. 2005. Microfossils,
4 Insects are and probably were the most 2nd edn. Blackwell Publishing, Oxford, UK.
numerically dominant life of Earth. Why Babcock, L.E. 1993. Trilobite malformations and the
have they a relatively poor fossil record? fossil record of behavioral symmetry. Journal of
5 Exceptionally-preserved biotas occur spo- Paleontology 67, 217–29.
radically throughout the Phanerozoic. Barrande, J. 1852. Systèm Silurien du Centre de la
Arthropods are usually well represented. Bohème. Recherches Paléontologiques, Vol. 1,
Planches, Crustacés, Trilobites. Prague and Paris.
Why? Briggs, D.E.G., Fortey, R.A. & Wills, M.A. 1993. How
big was the Cambrian evolutionary explosion? A
taxonomic and morphological comparison of Cam-
Further reading
brian and Recent arthropods. In Lees, D.R. &
Briggs, D.E.G., Thomas, A.T. & Fortey, R.A. 1985. Edwards, D. (eds) Evolutionary Patterns and Pro-
Arthropoda. In Murray, J.W. (ed.) Atlas of Inverte- cesses. Linnean Society of London, London, pp.
brate Macrofossils. Longman, London, pp. 199–229. 33–44.
(A useful, mainly photographic review of the Bruton, D.L. & Haas, W. 2003. Making Phacops come
group.) alive. Special Papers in Palaeontology 70, 331–47.