Temporal Sequences
Maggie Koopman and Erik Hoffmann

0.0
Now!
1.0
First hard parts
First multicellular
2.0
First eukaryotes
3.0
4.0
First life!
The beginning!
1.5 billion years

Sometimes you have a lot to work with...

...and sometimes you don’t!

Dooley et al., 2004
No crystalline rocks
• No absolute dating
• Imprecise age calibration
2 meters = 10 yrs or 10 million?

Dooley et al., 2004
Unconformities
• Stratigraphic gaps caused by non-deposition or erosion
• The bigger the time window, the bigger and more frequent the gaps will be

Dooley et al., 2004
Cover
• Prevents examination
• vegetation
• loose sediment/soil
• snow/ice/permafrost

100 km
Modified from Tibert et al., 2003.

• Resolution depends on depositional rates
– High rates allow high resolution
– Low rates allow low resolution
– Negative rates erase the record
• Not all environments are created equal!
Schindel, 1982

Dooley et al., 2004

Gingerich, 1983

• Preservable hard parts only!
• Morphological change only!

• Can’t detect fine changes.
• Small directional changes followed by reversals show up as variability within the population
Geary et al., 2002

• Long periods (relative to species durations) of morphological stasis coupled with brief periods of very rapid morphological change
• Stasis does NOT mean nothing is happening
• Changes in soft parts
• Changes in tolerances/behaviors
• Small directional morphological change followed by doubling back

• Lineage (size, hard parts, frequency)
• Location (range, availability)
• Temporal resolution ((sub)stage level)
• Character sets
• Usefulness/Interest

Does the fossil record need to be complete?
Can we work around the gaps?
Can we derive viable sequences from a spotty record?

Quality of the fossil record through time
M. J. Benton, M. A. Wills and R. Hitchin

• Offers evidence that the fossil record provides uniformly good documentation of past life.
•
Assesses the congruence between stratigraphy and phylogeny.

• Valid techniques for comparing large samples of cladograms to try to estimate variations in congruence between the fossil record for different groups of organisms and for different habitats
• RCI (relative completeness index)
• GER (gap ratio index)
• SCI (stratigraphic consistency index)
Depend on branching point estimates and calc. Of ghost ranges

(Huelsenbeck 1994)
• Fit of the record to the tree= proportion of the nodes that are stratigraphically consistent.
•Significance of the fit= generate a null distribution for SCI under the hyp. That the statigraphic fit is not better than expected at random.

Figure 2

• Hypothesis 1: congruence is better than random (bars to the left)
• Alternative hypothesis: congruence is worse than expected from a random model: direct conflict between data (bars to the right)
RCI SCI
Fig 1 a/b Benton et al 1999

• Difference in quality of trees
• Difference in quality of fossil record
• Stratigraphic problems
• Taxonomy
• Sampling density

Molecular Clock Divergence Estimates and the Fossil Record of Cetartiodactyla
Jessica M. Theodor
J. Paleontology 78 (1), 2004, p 39-44

• Ties molecular clocks to the fossil record
• Introduces cetaceans and hippopotamids

Molecular Clocks vs. the Fossil Record
• Artiodactyla/Cetacea split – 60 Ma
– Earliest fossil whales 53.5 Ma
– Earliest fossil artiodactyls 55 Ma
• Odontocete/Mysticete split – 34-35 Ma
– Rare at 34 Ma, good record ~30 Ma
• Hippopotamid/Cetacean split
– Earliest fossil whales 53.5 Ma
– Earliest fossil hippos 15.6-15.8 Ma
» Anthracotheres - ~43 Ma
• New study using one mitochondrial and one nuclear gene sequence

Boisserie et al., 2005

Take home messages
• The fossil record is necessary to calibrate molecular clocks (and refute the bad ones)
• The fossil record fills gaps in phylogenetic trees, allowing us to confirm evolutionary sequences

References
Benton, M.J., M.A. Wills, and R. Hitchin 2000, Nature. 403, 534-537
Benton, M.J. 2001, Proceedings of the Royal Society of London B. 268, 2123-2130
Boisserie, J.-R., F. Lihoreau, and M. Brunet 2005, Proceedings of the National Academy of Science 102
(5), 1537-1541
Dooley Jr., A.C., N.C. Fraser, and Z.-X. Luo 2004, Journal of Vertebrate Paleontology. 24 (2), 453-463
Geary, D.H., A.W. Staley, P. Muller, and I. Magyar 2002, Paleobiology. 28 (2), 208-221
Gingerich, P.D. 1983, Science. 222, 159-161
Gingerich, P.D. 1984, Science. 226, 995-996
Gingerich, P.D. 2002, Cetacean Evolution
Gould, S.J. 1984, Science. 226, 994-995
Huelsenbeck, J.P. 1994, Paleobiology. 20 (4), 470-483
Koch, C.F. 1978, Paleobiology. 4 (3), 367-372
Levinton, J., L. Dubb, and G.A. Wray 2004, Journal of Paleontology. 78 (1), 31-38
Lihoreau, F., and J.-R. Boisserie 2004, Journal of Vertebrate Paleontology 24 (Supp. 3), 83A
Rose, K. 2001, Science. 293, 2216-2217
Schindel, D. 1982, Paleobiology. 8 (4), 340-353
Schopf, T.J.M. 1982, Evolution. 36 (6), 1144-1157
Theodor, J.M. 2004, Journal of Paleontology. 78 (1), 39-44
Tibert, N.E., R.M. Leckie, J.G. Eaton, J.I. Kirkland, J.-P Colin, E.L. Leithold, and M.E. McCormick
2003, in Olson, H.C. and R.M. Leckie, eds., Micropaleontologic Proxies for Sea-Level Change and
Stratigraphic Discontinuities : SEPM Special Publication No. 75, 263-299
Wills, M.A. 1999, Systematic Biology. 48 (3), 559-58