In spite of the best efforts at creating 'convincing' Evolutionary 'tree'
for Trilobites as found in the geological record,
its obvious that the results come up rather short:
(1) There are as many identified 'species' in each previous time period (or more) than in the last.
(2) The number of 'species' actually doesn't appreciably vary, except in the negative.
Here is the 'best' tree that can be assembled out of fossils found 'in-strata':
It should be recalled also that no DNA is available for analysis,
and therefore the ONLY 'tree' that can be constructed is based upon
geological layering and its interpretation, rather than actual 'phyogenetic trees',
as is done with modern animals utilizing DNA samples.
On the other hand, this part of the fossil record is extensive,
and ought to be more reliable even than attempts at atomic dating methods,
since the location in the strata of each fossil is exactly known.
While the vertical placement in the column is quite certain,
the 'branches' and tree-like connections are all completely speculative,
and based only on the visible morphology available.
Looking at the fossils themselves leaves the viewer in a good position to
question both the groupings and the alleged descent of all the members shown.
Cambrian: 14-15 different types are found.
Ordovician: 14-15 different types are found.
Silurian: 8 different types are found.
Devonian: 6 different types are found.
Carb. Period: NONE....
Permian: 1 type found.
Just as in the insect world, we see apparently an 'explosive speciation',
followed by later decline in the number of types.
This makes even less sense when Darwinian Natural Selection
is considered, because these are Ocean species all in the same 'area'
(i.e., vertical column of mud and silt). So its quite difficult to
speak of 'isolated continents' and other factors, which on LAND,
seem to make sense according to Darwinian principles of
Isolation --> mutation --> distinct populations --> species bifurcation.
Here of course any alleged detection of 'speciation' is
entirely based on physical differences in individual fossils,
which MAY represent different species, but also may
in part be attributed to stages of growth within a species,
or local variation of the same species.
Evolution: no solid evidence.