Unformatted text preview: every step between a
bulldog and a greyhound.” WHERE ARE THE TRANISTIONAL FOSSILS?
1. IMPERFECTIONS IN THE FOSSIL RECORD
2. THEY WILL BE FOUND 1861 31,000 Invertebrate Fossil Species Known
Lots 3. PUNCTUATED EQULIBRIUM
Transitional Species don’t last long
Transitional Species Z Intermediate in
in time Species A Like Archaeopteryx Evolution of the
in size Decrease in the
number of toes
number Increase in
complexity of the
molars 1 mya Increase Originally believed
to be a linear path 2 mya 23 mya 34 mya 556 mya
56 But what if the evolutionary pattern is like Darwin envisioned? Most fossil lineages are probably
branching Four recent horse species in Africa AND NOW
Here is a story of the discovery of a spectacular
series of transitional species.
Although we show it as a linear series, it is
almost certainly a branching scheme with still
many missing pieces. It begins with Charles Darwin...
View Full Document
- Fall '07
- Evolution, transitional species