From the first
fossil selection page select:
A: Fossil
(1,247 specimens) – group – invertebrate
– trilobite (you should have now selected
have 72 specimens)
B: Now
select age –
this gives you a page with a geological map and strata column
Select File
on your browser and Print to produce a hard
copy of this page
C: In turn,
select each of the geological periods from the Precambrian upwards and
for each period:
1: select the all
option
2: record the number of trilobites
next to the hard copy strata column.
3: return to the map page by pressing
twice the back button at the bottom of the
page
D:
Plot a simple histogram where its axes are the number of specimens vs
the geological period
E: Now
use your information to describe the evolution of the trilobites.
-
When did they appear?
-
When were they most numerous?
-
When did they decline?
-
In what period did they become extinct?
-
Why do you think are there no trilobites
in Southeast England?
The six periods Cambrian to Permian contain fossils of many species that are now extinct. These periods were given the term Palaeozoic from the Greek meaning 'ancient life'.
The three periods Triassic, Jurassic and Cretaceous contain fossils such as ammonites, which although extinct, show similarities to modern forms. These periods are given the term Mesozoic, meaning 'middle life'.
The Palaeogene, Neogene and Quaternary periods all contain fossils that are very similar to modern species. These periods are termed Cenozoic meaning 'recent life'.
F: Now try this activity again, this time using graptolites, ammonites and gastropods – these represent
different ages of fossils. Compare them with trilobites
