10 million or 1 million | The Octopus News Magazine Online
  • Thanks for visiting! TONMO is the world's greatest online cephalopod enthusiast community, with interactive content going back to May of 2000, and a biennial conference. If you'd like to join in on the fun, become a TONMO member -- it's easy and free. Follow us on Facebook and Twitter for more cephy goodness.

10 million or 1 million

POD-L

O. bimaculoides
Registered
Joined
May 29, 2005
Messages
65
Location
Comox, B.C.
#2
Kevin
I think a lot of math is involved to "normalize" the data , depends on what equation and data manipulation is used. I remember a similar debate over how soon ammonites disappeared at the KT boundary. Some consider them to be on their way out millions of years before KT. Peter Ward did a study at the KT boundary in Spain and discovered they were well represented right up to the boundary. Analysis is a lot like statistics!
 

Architeuthoceras

Architeuthis
Staff member
Moderator
Joined
Nov 19, 2002
Messages
2,407
Location
somewhere under the desert sky
#4
If the fossil record was perfect I suppose the two numbers would be a little closer. The dating of the rocks may also play a role in the two results. The number of different phyla used to calculate diversity may skew the results. But they both used ammonoids. :hmm:
 

Hajar

Haliphron Atlanticus
Registered
Joined
Mar 7, 2009
Messages
540
#6
Have you read the two papers Kevin? Do they have the same definition of recovery?

Brayard et al. looks like a thorough piece of work. They say "This explosive and nondelayed diversification contrasts with the slow and delayed character of the Triassic biotic recovery as currently illustrated for other, mainly benthic groups such as bivalves and gastropods."
 

Hajar

Haliphron Atlanticus
Registered
Joined
Mar 7, 2009
Messages
540
#7
By the way, I liked the discussion and reply on your "Gastropod evidence against the Early Triassic Lilliput effect" paper.
 

Architeuthoceras

Architeuthis
Staff member
Moderator
Joined
Nov 19, 2002
Messages
2,407
Location
somewhere under the desert sky
#8
Hajar;171858 said:
Have you read the two papers Kevin? Do they have the same definition of recovery?

Brayard et al. looks like a thorough piece of work. They say "This explosive and nondelayed diversification contrasts with the slow and delayed character of the Triassic biotic recovery as currently illustrated for other, mainly benthic groups such as bivalves and gastropods."
The library here doesn't have a subscription for electronic copies, the hard copy comes about the middle of the month, so I am patiently waiting. :sad:

From the news release I assume Whiteside & Ward are using morphotypes to determine swimmers and floaters, with the return of the swimmers bringing recovery. Brayard et al, counted genera, comparing the numbers with Permian and later Triassic numbers. Of course they both use the Carbon isotope cycles to help calibrate time.

Just as a side note, in my experience, the Smithian rocks (~1.5-2 My post P/T) in Utah have more diversity in both genera and morphotypes than any other bed of any age I have collected.

Hajar;171859 said:
By the way, I liked the discussion and reply on your "Gastropod evidence against the Early Triassic Lilliput effect" paper.
Thanks! A lot more defence needed in science than I had imagined. :sly:
 

Architeuthoceras

Architeuthis
Staff member
Moderator
Joined
Nov 19, 2002
Messages
2,407
Location
somewhere under the desert sky
#9
I just got a copy of the Whiteside & Ward paper... verrrry interesting :grin:

They attribute the "chaotic" Carbon Isotope Cycles to a destabilized ecosystem (functional redundancy) rather than volcanogenic CO2. They discount eustasy on statistical grounds.



On the time scale above, their "Chaotic carbon" episodes correlate (P/T & T/J boundaries) with some "Chaotic sequences" (eustacy), that may or may not correspond with the carbon cycles, and that could be of volcanic and/or glacial origin, rather than biologic.
There is probably a middle ground somewhere, when all things are considered (more study needed).

Ammonoid wise; they counted genera from the Pacific Coast (paleo?) of North America and divided them into morphotypes. Serpenticones and heteromorphs are considered floaters and all others swimmers.
 

Attachments

Members online

No members online now.

Monty Awards

TONMOCON IV: Terri
TONMOCON V: Jean
TONMOCON VI: Taollan
TONMOCON VII: ekocak

About the Monty Awards