Hi Bob,
You are assuming that we have found the very first member of the genus Homo
who ever lived on earth. And as you are well aware, but have forgotten
temporarily, given a small population of humans, the data is exactly what
we would expect given the nature of the fossil record itself. Obviously,
when a species/genus/family first appears in the fossil record it is NOT
the time when the very first example appeared on earth. Statistically
species would live much earlier than their first fossil examples would
allow. This is because fossilization is relatively rare. For instance, it
is highly unlikely that the very first dinosaur was preserved in the fossil
record. Their rarity would mean that it would be unlikely for them to be
fossilized. So a small population can exist for a long time and leave no
fossils of themselves. So, if the first fossil of the genus Homo is found
at 2.4 myr, the first member of the genus was most assuredly prior to this
time.
Secondly, to find the earliest possible fossil of a group, one must be sure
that you have looked at the exact geographic region where the group first
evolved. If you don't know where that is, you can't be sure that you have
the earliest known case of fossilization. Afterall, it takes some time for
the group to reproduce, spread out over a large enough area so that they
can leave a sufficient number of fossils so that there is a liklihood of
one being found.
So, how much earlier could it be? How do we get a feel for how long a
species/genus/family could exist prior to their first known fossil example?
One way is to look at the gap between the earliest and second earliest
fossil examples for various groups. In 1970 each fossil group had an
earliest appearance time. Today, new discoveries have pushed the earliest
occurrences back for many fossil groups. For example, say that the earliest
known fossil caecilian is 100 million years prior to the second fossil
example, we KNOW that caecilians lived on earth for that 100 million years,
but left no trace. Here is the data. At the end of this list I will talk
about its implications for human fossils.
Group Temporal gap between Reference
first and 2nd examples
Therinzosaur 94 myr Xijin Zhao, Xing Xu, "The Oldest
Coelurosaurian,"
Nature 394(1998) p. 234
Hollow filament 400 myr Science News, March 12, 1994, p. 173
plants
Terrestrial 110 myr Science, Jan. 28, 1994, p. 494-498
Life
Caecilians 100 myr Science News, 138, Oct. 27, 1990, p. 270.
Tarsiers 30 myr Nature, 368, April 14, 1994, p. 586.
Turtles in Africa 60 myr Nature, 369, May 5, 1994, p. 55.
Birds 8 myr Science, Feb. 14, 1992, p. 845
coprolites 90 myr Nature, Sept. 28, 1995, p. 329
Two-gilled mushrooms 60 myr Nature, 377, Oct. 12, 1995, p. 487
eclogites 900 myr Geology, Dec. 1995, p. 1067
(not a fossil)
fish 25 myr Nature, 379:628-630, Feb. 15, 1996, p. 628
Vascular plant 50 myr Nature, 379, Feb. 15, 1996, p. 592
Spiders 55 myr Nature, 379, Feb. 8, 1996, p. 498
thrips 20 myr Nature, 380, April 18, 1996, p.615
Dipteria 20 myr Nature, 380, April 18, 1996, p. 617
coleoptera 20 myr Nature, 380, April 18, 1996, p. 617
Tyranosaur 20 myr Dallas Morning News, June 24, 1996, p. 10D
Madagascaran birds 20 myr Nature 382, August 8, 1996, p. 532
Proboscidean 7 myr Nature, 383, (Sept. 5, 1996), p. 68-70,
p. 68-69
chordates 10 myr Science News, 150, Nov. 16, 1996, p. 311
land snails 220 myr The Terrestrial Invasion,
(CambridgePress, 1990), p. 11-12
tetrapod 25 myr Science, July 29, 1994, p. 639-641. p. 641
deepsea vent organisms 420 myr Nature, 385, Jan. 9, 1997, p. 146-148, p.
146
bisexual plants 5 myr Nature, Jan. 30, 1997, p. 401
pollen eating insects 150 myr Science, 276(1997), p. 1035
sponge 35 myr Science 279(1998):879-882, p. 879
grasses 25 myr American Journal of Botany, 78(1991):7:
1010-1014, p. 1010
Marine turtles 10 myr Nature, 392(1998):651.
crawfish 65 myr Geology 26(1998):6:539-542, p. 539
Maldybulakia 30 myr Nature, 394(1998): 172-175, p. 172
Now, each of the above cases is an EXTENSION of the previous range of the
fossil group by the amount noted. Thus the new discoveries PROVE that the
previously thought oldest example is really not an oldest example. All I am
asking for is a 3 million year gap in the fossil record of the genus Homo.
What I am asking for is quite conservative compared with the KNOWN times
during with other groups left NO fossil record.
Now, if you think what I am asking for is out of line with the known fossil
record, then please tell me why.
glenn
Adam, Apes and Anthropology
Foundation, Fall and Flood
& lots of creation/evolution information
http://www.isource.net/~grmorton/dmd.htm