Presentation on theme: "1 WHEEEEE ! 2 What are we Doing Today? Whale fossil hunt Whale ankle comparisons Whale DNA comparisons WHALE EVOLUTION."— Presentation transcript:
1 WHEEEEE !
2 What are we Doing Today? Whale fossil hunt Whale ankle comparisons Whale DNA comparisons WHALE EVOLUTION
3 Becoming Whales
4 Diversity of Whales Today Mysticetes (baleen whales):
5 Diversity of Whales Today Odontocetes (toothed whales):
6 But Where Did They Come From? ONE OF DARWIN’S IDEAS… … I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale. Charles Darwin, The Origin of Species, 1859 (first edition), Chapter 6: Difficulties on Theory Darwin was wrong about the BEAR (he removed this idea in later editions), but spot-on with the process – NATURAL SELECTION.
7 Here’s a Peek into the Past… So, Where DID Whales Come From?
8 Moving in… Notice that the earliest MAMMALS… were TERRESTRIAL - with LEGS !
9 But WHALES SWIM; they DON’T WALK ON LAND ! So - Where DID Whales Come From? What would the earliest whales look like?
10 The Earliest MODERN WHALES… 65mya NOW MIOCENE 23 mya Only go back to about 23 mya… the beginning of the MIOCENE… Great swimmers… but NO WALKING LEGS ! 5 mya
11 HOWEVER ! 65mya NOW MIOCEN E 23 mya We DO have some whale-like fossils, with strange teeth, from the EOCENE ! 5 mya
12 But… Where’s the Eocene? NOW 4.5bya 65mya NOW 55 mya 34 mya EOCENE Miocene: Earliest modern whales 23 mya
13 OK! So, where shall we look for Eocene Fossils? The Tethys Sea India Moved North… …Squished into Asia… Mountains of Pakistan 55 38
14 Where shall we look? Pakistan Lots of exposed marine Eocene rocks in the Pakistan mountains
15 Let’s Hunt Whale Fossils… Work in pairs Open Your Eocene Timeline Remove whale strips from plastic bag Listen for descriptions and timing Place whale strip on timeline Wait for next “discovery”
36 Ungulate Foot Bones… FOSSIL HORSE Heel Bone Ankle Bone FOSSIL PIG
37 Whale Ankles? Mesonychid Prim.Perissodactyl Prim. Artiodactyl Pakicetus Pig Compare ankle bones… one big ridge two small ridges
38 Whale Phylogeny, 2001 Philip Gingerich
39 But WHICH Artiodactyls? Will DNA Tell Us? Let’s Compare DNA…
40 DNA Analysis Compare segments of beta - casein gene
41 DNA Analysis Compare segments of beta - casein gene
42 DNA Differences
43 DNA Differences
44 DNA Differences Fewer than five differences… 2 porpoise & sperm whale 3 porpoise & right whale 3 sperm whale & right whale 3 sperm whale & hippo 3 porpoise & hippo 3 right whale & hippo 3 giraffe & deer 3 giraffe & cow 4 cow & deer
45 DNA Differences Seven differences… 7 pigs and peccaries DNA Differences Remaining species… Higher numbers - more distantly related
46 Phylogenetic Tree - WHALES Based on DNA Differences
47 Provisional Phylogeny - Cetartiodactyls
49 Whale Evolution Recap Fossil teeth link whales to the 4-legged mesonychids of the Paleo-Eocene Tiny hooves on mesonychids and early whale toes tie whales to the ungulates Ankle bones of early whales point to artiodactyl ungulates as the closest relatives of whales
50 Whale Evolution Recap DNA confirms the artiodactyl connection and points to hippos as the closest cousins of whales Consilience: these multiple independent lines of evidence strengthen, narrow and confirm the hypothesized close relationship between whales and artiodactyls