Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
4 online now:
Newest Member: popoi
Post Volume: Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 13/17 Hour: 0/1


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Pakicetus being presented with webbed feet.
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 301 of 305 (265132)
12-02-2005 6:58 PM
Reply to: Message 299 by arachnophilia
12-02-2005 6:50 PM


Re: cute pics but no real claim on your part
Your argument is bogus because of the following claim.
and clearly indicate that it eats things that live in water, and ONLY things that live in water.
Please substantiate that claim or retract it and admit you made a mistake.
This message has been edited by randman, 12-02-2005 07:01 PM

This message is a reply to:
 Message 299 by arachnophilia, posted 12-02-2005 6:50 PM arachnophilia has replied

Replies to this message:
 Message 304 by arachnophilia, posted 12-02-2005 7:15 PM randman has not replied

arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 302 of 305 (265133)
12-02-2005 7:03 PM
Reply to: Message 298 by randman
12-02-2005 6:47 PM


Re: comparison with crocodiles
*sigh*
ok, randman, nevermind. don't think. you need to know something about biology first, so it's schooling time.
crocodilian teeth do not interlock and alternate. they also protrude above and below the gumline, and often below the jaw. reptilian teeth are all analagous forms, just varying in size (exlucing dimetrodons and ancestral mammals). whales have similar, but not analagous teeth. note the differences in curvature.
crocodile teeth are more similar to these guys:
flattened at the edges, round in the center. whale teeth are round all the way around. reptilian teeth tend to be serated on the front and back egde, i don't imagine that whale teeth are because they don't have edges. whale teeth are slightly bulbous towards the end, reptile teeth are larger towards the base. whale teeth have slight second curve in teh root structure, reptilian teeth don't. reptile teeth point backwards, whale teeth point down.
the jaw structure works differently, too. whales have a post-orbital ridge, that the musclature attaches through, like most other mammals. reptiles have a flat hinge. the cranial structure in that area is also different, mammals have a recession for the muscle to attach to, reptiles have a hole.
This message has been edited by arachnophilia, 12-02-2005 07:04 PM

אָרַח

This message is a reply to:
 Message 298 by randman, posted 12-02-2005 6:47 PM randman has not replied

arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 303 of 305 (265134)
12-02-2005 7:08 PM
Reply to: Message 300 by randman
12-02-2005 6:50 PM


because i like paleontology...
... i can tell the difference.
the false killer whale and the german shepherd look more similar to me than the whale and the crocodile. for instance, all of the dentiary differences i described above.
bot mostly the jaw/ear structure, the temple reagion, the orbital structures, and the generally more intricate structure, opting for thin solid structures instead of heavy ones with holes.
this is seriously elementary biology, randman. i'm sorry i ever gave you the idea to compare things, because clearly you don't even know how to look at some animal's skull, and conclude that therefor no else must know either.

אָרַח

This message is a reply to:
 Message 300 by randman, posted 12-02-2005 6:50 PM randman has not replied

arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 304 of 305 (265135)
12-02-2005 7:15 PM
Reply to: Message 301 by randman
12-02-2005 6:58 PM


pakicetus diet
Your argument is bogus because of the following claim.
and clearly indicate that it eats things that live in water, and ONLY things that live in water.
Please substantiate that claim or retract it and admit you made a mistake
2 seconds on google to confirm what honestly was my own analysis of its teeth:
quote:
C. Anatomical Transitions in Archaeocetes
  * Dentition
    o initially - complex heterodont teeth with big canines
    o reduction in heterodonty - associated with fish eating diet
    o finally - simpler cheek teeth; some conical; some triangular & serrated
Not Found (class notes)
quote:
FROM HOOVES TO FLIPPERS: NEW INSIGHTS INTO THE ECOLOGY OF EOCENE MARINE MAMMALS FROM STABLE ISOTOPES
CLEMENTZ, Mark T.1, GOSWAMI, Anjali2, KOCH, Paul L.1, and GINGERICH, Philip D.3, (1) Earth Science, Univ of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, clementz@es.ucsc.edu, (2) Committee on Evolutionary Biology, Univ of Chicago, Chicago, IL 60637, (3) Museum of Paleontology, Univ of Michigan, Ann Arbor, MI 48109
The evolution of cetaceans and sirenians is marked by similar morphological changes, such as loss of hindlimbs and development of tail flukes, which are associated with adaptation to a fully aquatic existence. Yet, how these changes correlate with ecological transitions within these lineages remains unclear. Coupled carbon and oxygen isotope analysis is one source of ecological information for early taxa within these groups. Enamel d13C values are controlled by diet and are labeled by the d13C composition of primary producers at the base of the food web. Enamel d13C values are low for freshwater foragers, intermediary for C3 terrestrial consumers, and high for marine foragers, particularly consumers of marine macrophytes. Mean enamel d18O values can reflect the d18O composition of environmental waters, and thereby distinguish marine and terrestrial taxa. However, physiological and dietary differences also influence enamel d18O values, which complicates interpretation of mean values. An alternative is to look at differences in d18O variance among populations, since terrestrial taxa typically exhibit higher variance than aquatic taxa.
Using a coupled isotope approach, we assessed the habitat and dietary preferences of early cetaceans (Pakicetus, Basilosaurus, and Dorudon) and sirenians (Protosiren, Eosiren, and Eotherium) through comparison with co-occurring terrestrial mammals. Pakicetus and Protosiren represent basal members of these two lineages that morphologically were still capable of terrestrial locomotion, while the other taxa were most likely fully aquatic. Among cetaceans, the mean d13C value for Pakicetus was significantly lower than terrestrial taxa, as was the d18O variance, suggesting that Pakicetus was principally aquatic and foraging within freshwater ecosystems. More derived cetaceans, Basilosaurus and Dorudon, also showed low d18O variance, but mean d13C values were higher than terrestrial taxa, indicating these cetaceans were marine foragers. Likewise, sirenians exhibited low d18O variance indicative of aquatic habitat use, but d13C values for all sirenians, including Protosiren, were significantly higher than values for all other taxa, and represent the earliest clear evidence of feeding on seagrass by any lineage of mammals.
http://gsa.confex.com/...1AM/finalprogram/abstract_28631.htm (emphasis mine)
This message has been edited by arachnophilia, 12-02-2005 07:16 PM

אָרַח

This message is a reply to:
 Message 301 by randman, posted 12-02-2005 6:58 PM randman has not replied

AdminJar
Inactive Member


Message 305 of 305 (265136)
12-02-2005 7:17 PM


time to witch this brew
closing it and God willing the stake through its heart will be effective.

Comments on moderation procedures (or wish to respond to admin messages)? - Go to:
  • General discussion of moderation procedures

  • Thread Reopen Requests

  • Considerations of topic promotions from the "Proposed New Topics" forum
  • New Members: to get an understanding of what makes great posts, check out:
  • "Post of the Month" Forum

  • "Columnist's Corner" Forum
  • See also Forum Guidelines, Style Guides for EvC, and Assistance w/ Forum Formatting

    Newer Topic | Older Topic
    Jump to:


    Copyright 2001-2023 by EvC Forum, All Rights Reserved

    ™ Version 4.2
    Innovative software from Qwixotic © 2024