RSS 2.0 Feed

» Welcome Guest Log In :: Register

Pages: (29) < [1] 2 3 4 5 6 ... >   
  Topic: Discussing "Explore Evolution", Have at it.< Next Oldest | Next Newest >  

Posts: 766
Joined: Jan. 2006

(Permalink) Posted: July 13 2007,19:36   

Seeing the ellipse in that quote made me curious as to what the whole thing says.
Angiosperms appear rather suddenly in the fossil record during the Jurassic [b][208–145 million years ago (Mya)][b], with no obvious ancestors for a period of 80–90 million years before their appearance. Nevertheless, the existence during the Jurassic of all known sister taxa to the angiosperms implies that the angiosperm lineage must have been established by that time [1]. However, this ancestral lineage, coined ‘angiophytes’, is unlikely to be equivalent to angiosperms as known from the Cretaceous (145 Mya) through to recent forms because it might have lacked many of the characteristic angiosperm features [2]. It is presumed that angiophytes went through a period of little diversification during the Late Triassic (220 Mya) and Jurassic, either because the diversity-enhancing features, such as flowers, of the crown-group angiosperms had not yet evolved in stem angiophytes or because the diversity among angiophytes was inhibited during the Jurassic by environmental conditions or biotic interactions [2].
(my emphasis).

The removed portion describes the range of the Jurassic period, rather than the "Big Bloom." But a couple paragraphs later, some more interesting detail is given:

The fossil record provides excellent evidence for this rapid diversification in floral form during the earliest phases of recorded flowering plant history [5]. Only 10–12 million years elapsed between the first fossil records (not, vert, similar130 Mya) and clear documentation of all of the major lines of flowering plants 1 and 6. This diversification of angiosperms occurred during a period (the Aptian, 125–112 Mya; Figure 1) when their pollen and megafossils were rare components of terrestrial floras and species diversity was low 1 and 6. Angiosperm fossils show a dramatic increase in diversity between the Albian (112–99.6 Mya) and the Cenomanian (99.6–93.5 Mya) at a global scale 7, 8, 9 and 10 (Figure 1).

Shockingly, Figure 1 is a "gradually branching tree," which these mysterious critics say the data does not support. It's too bad the sample cuts off there; I'd like to know what these critics do think the data supports.

I also have a brief question for Paul Nelson, if he does show up. Do you honestly believe that this is a college-level textbook, appropriate for use at the University of Washington, for example?

Source:Trends in Ecology & Evolution
Volume 20, Issue 11, November 2005, Pages 591-597

"Why waste time learning, when ignorance is instantaneous?" -Calvin

  859 replies since July 13 2007,13:04 < Next Oldest | Next Newest >  

Pages: (29) < [1] 2 3 4 5 6 ... >   

Track this topic Email this topic Print this topic

[ Read the Board Rules ] | [Useful Links] | [Evolving Designs]