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Old 01-31-2003, 06:45 AM   #1
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Okay, in the midst of a typical long series of creationist quote mining on evcforum, bashing the Hyracotherium to equiid lineage, my opposite number came up with a quote I haven't encountered, and can't find a decent reference rebutting or explaining. Since the thread was closed (it was waaaaay off topic), I've got time to prepare a really scathing reply, so would like to close the loop on this quote as well.

Quote:
Phylogenetic systematics of basal perissodactyls Froehlich, DJ, Journal of Vertebrate Paleontology, 1999, 19(1): 140

"The relationships among basal perissodactyls and among those taxa historically included in Hyracotherium are complicated. These taxa are morphologically similar, possessing few of the character states that diagnose the crown groups. To understand better these relationships, cladistic techniques were used to generate a matrix of 41 taxa and 125 characters including five non-perissodactyl outgroup taxa, representative basal tapiroids, brontotheres, chalicotheres, palaeotheres, and equids. ... The results also suggest that Hyracotherium is not representative of the basal morphology of the perissodactyls, and no currently identified fossil provides a good candidate for that morphology."

David Froelich also states:

"The reason that Hyracotherium has been excluded from the equid lineage is that it falls on a side branch toward the paleotheres. It no longer is an equid. Therefore, the name cannot be used (If it were it would represent a group of organisms for which you did not have a single ancestor, nor all of the descendants, ie. polyphyletic) Eohippus on the other hand was named by Marsh from a single worn maxillary fragment found in New Mexico (San Jose fm.) Unfortunately, the type material is not diagnostic (and currently mislayed) and either Eohippus is a member of a genus called Xenicohippus (an abberant equid) or is a basal tapiromorph called Systemodon (the type Eohippus material cannot be distinguished from these two possibilities because it is so worn)."
The only thing I've found on Froelich says he's a biology teacher at Austin Community College in Texas. However, his cv indicates he's got background in the right fields, including working at a reputable paleontology museum etc.

So does anyone have any info on either Froelich himself or the apparent claim that Hyracotherium is no longer considered an ancestor of the equiids, tapirids, etc. Perhaps someone has access to the original Journal of Vertebrate Paleontology article? There appear to be at least two possible alternative explanations going on here, but sitting in Ukraine without library access is killing me...

Thanks for your help.
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Old 01-31-2003, 07:23 AM   #2
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You can check him out here .
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Old 01-31-2003, 07:25 AM   #3
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Dear oh dear, Morpho, never heard of Google? What I assume is the abstract is here:
http://www.vertpaleo.org/jvp/19-140-159.html

Quote:
Phylogenetic systematics of basal perissodactyls

Froehlich, DJ, Journal of Vertebrate Paleontology, 1999, 19(1): 140

The relationships among basal perissodactyls and among those taxa historically included in Hyracotherium are complicated. These taxa are morphologically similar, possessing few of the character states that diagnose the crown groups.

To understand better these relationships, cladistic techniques were used to generate a matrix of 41 taxa and 125 characters including five non-perissodactyl outgroup taxa, representative basal tapiroids, brontotheres, chalicotheres, palaeotheres, and equids. A maximum parsimony analysis of this matrix using PAUP 3.0s generated two most parsimonious trees (length 627, CI 0.32).

This analysis supports a monophyletic perissodactyl clade composed of the Tapiromorpha and the Hippomorpha.

The tapiromorph clade consists of a number of basal tapiroids, a paraphyletic isectolophid group, the ceratomorphs (tapirs, and rhinoceroses and extinct relatives), and the ancylopods (chalicotheres and relatives). The basal tapiromorphs are distributed holarctically, indicating divergence and dispersal by the latest Paleocene.

The hippomorph clade is composed of two distinct clades, the European palaeothere clade and the equids.

The brontotheres are tentatively derived from within the palaeothere clade. Hallensia is identified as the most basal palaeothere, sister taxon to Hyracotherium leporinum and all more derived palaeotheres.

The equid clade is composed of a stratigraphically consistent sequence of paraphyletic equid taxa, and a clade composed of Hyracotherium craspedotum and Xenicohippus. The majority of the pectinately arranged equid taxa in the analysis lack autapomorphies, which suggests that these taxa may represent lineage segments from a single anagenetically evolving lineage.

The results also suggest that Hyracotherium is not representative of the basal morphology of the perissodactyls, and no currently identified fossil provides a good candidate for that morphology.
Now, if you can decipher that lot, let me know what it means!

[Edited to stick in some paragraphs. It's a bit more comprehensible now.]

I’ve heard Froehlich’s name before, and the Google for him and hyracotherium which found that also brings up enough stuff to make me think the guy does know what he’s talking about. He’s certainly no creationist, it just seems that hyracotherium is a basal palaeothere, not an equid. IOW, close, but not the right critter.

There’s a cladogram at here, but with that daisy-wheel-printout design, I can’t make head nor tail of it .

See also Froehlich’s post here:

http://www.cmnh.org/dinoarch/1996Feb/msg00473.html

An amusing aside: it seems that person who lost Marsh’s type specimen of Hyraco / Eohippus was the hot-blooded dino chap Bob Bakker.... Not quite sure why I find that funny, but I do.

So Morpho, what was your creationist saying? Looks to me, insofar as I can tell, that this is no different to deciding that, say, Australopithecus africanus is a side branch, not on the direct line. But as any cladist will tell you, we’re very unlikely to find stuff actually on the line, only the stuff near it (that, I gather, is why cladograms are drawn like that!)

Hope that helps. This also looks like a job for Patrick (ps418). If he doesn’t show up, you could email him: his details are on page 8 of the P’s.

Cheers, DT
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Old 01-31-2003, 08:14 AM   #4
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Thanks DT et al.

I got that part, actually - including the abstract from the journal (google my left, erm, whatever ). That's not the problem. The difficulty is the cretinist is using the article to bolster his claim (based on our old pal Gish's famous Impact #87 article) that Hyracotherium is a hyrax, by claiming that Froelich is saying it's not an equiid (or rather, basal to the equiids). And yes, I've got all the usual counters - teeth, toe pads vs heel pads, etc. Heck, here's the thread if you're interested: start here, although bart's quote mine started back in msg #66. I can easily eviscerate the quote mine, but I need somebody to 'splain me what Froehlich was REALLY talking about so I can hammer the only substantive bit of actual information my, uhhh, "counterpart" came up with.

My motivation for opening a new thread on evcforum in response is the diatribe in message 87 - I ain't a' gonna let that slide - them's fightn' words.
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Old 01-31-2003, 08:50 AM   #5
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Quote:
And yes, I've got all the usual counters - teeth, toe pads vs heel pads, etc.
Doubtless you’re aware of the TO page Is ‘Dawn Horse’ a Hyrax? The two pictures alone are enough to quash that bit of twaddle:

Hyracotherium:


Hyrax:


(Ah, have looked at the thread, and see you’ve already done the pic thing. Still, I like a nice picture, and hope the lurkers here do too .)

I suspect what Froehlich was saying is pretty well covered in the abstract, that Hyraco isn’t a direct horse ancestor. But so? It ain’t no hyrax either, and, most importantly, it is a bloody sight closer to being a horse ancestor than it is to a hyrax. Right time, right place, and morphology right enough that it was thought to be ancestral for a long time. Like I say, we won’t generally be finding things on the direct line anyway.

If he wants a basal equid, then we’re all out of luck. If he’s only bothered about the hyrax connection, then you’ve got him anyway. I love his sentence:

Quote:
In addition, you Hyracotherium (eohippus) has been utterly kicked out of the horse family as determined by cladistics.
Typical creationist hyperbole. Get him to look at that cladogram. Hyraco isn’t on the direct line, but if that’s utterly kicked out of the horse family, then why’s it even on there? Depends on the term ‘family’. It’s not an equid... and yet it slots in near the base of their clade just like a hyrax wouldn’t.

Which isn’t much help really I guess. It’d be nice to have something easy to hit this bozo with (a baseball bat springs to mind ), rather than have to explain cladistics to him. But that’s the nature of these discussions. The more you explain, the more you have to explain.

Cheers, DT
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Old 01-31-2003, 11:27 AM   #6
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Here's a short summary:

There is not much to distinguish different species of early perissodactyls, and they have few of the distinctive features of different groups of present-day perissodactyls. In other words, there is not much that can be used to determine whether some early perissodactyl was an ancestor of the horses, the tapirs, the rhinos, any combination of these, or none of these.

However, a likely conclusion is that "none of these" applies for Hyracotherium; it is thus an offshoot that has left no present-day survivors.

My comment:

That difficulty in distinguishing ancestors from offshoots shows that higher-level intermediates are common in the fossil record, even if intermediates between many fossil species are not.
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Old 02-02-2003, 10:14 PM   #7
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Thanks, DT - I think I'm getting the glimmer of an idea for a response.

lp, once I open the thread, feel free to jump in - especially if you see that I'm making some kind of mistake (it's nice to have someone backstop on these things.) I'd rather be corrected in open forum than say something stupid...
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Old 02-02-2003, 10:44 PM   #8
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lpetrich:
However, a likely conclusion is that "none of these" applies for Hyracotherium; it is thus an offshoot that has left no present-day survivors.

Well, from a cladistics point of view we shouldn't even ask whether Hyracotherium is a direct ancestor of horses or not, the important question is whether it shares a more recent common ancestor with horses than with other perissodactyls...what's the general opinion on this?
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Old 02-03-2003, 04:33 AM   #9
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Yes, cladistics do frown upon ancestor-descendant evolutionary scenarios. To them, all oganisms are part of ever increasing nested hierarchies, of sister-organisms, sister-groups, sister-taxa, etc, with ever diverging evolutionary relationships. Henry Gee's book In Search of Deep Time is a good intro to cladistics.
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Old 02-03-2003, 07:51 PM   #10
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Quote:
Originally posted by Morpho
Thanks, DT - I think I'm getting the glimmer of an idea for a response.

lp, once I open the thread, feel free to jump in - especially if you see that I'm making some kind of mistake (it's nice to have someone backstop on these things.) I'd rather be corrected in open forum than say something stupid...
If Froehlich ever thought that Hyracotherium was not an early equoid he has changed his mind now. Here is a copy of an abstract from a more recent paper by him. Froehlich clearly states that his analysis supports Hyracotherium as a primitive equoid.

Quote:
Quo vadis eohippus? The systematics and taxonomy of the early Eocene equids (Perissodactyla)
DAVID J. FROEHLICH
The systematics and taxonomy of early Eocene equids are investigated. A paraphyletic sequence of equid taxa is recovered from a phylogenetic analysis of 40 taxa and 121 characters. This analysis supports the identification of Hyracotherium as a primitive equoid and its restriction to the genotype, Hyracotherium leporinum. Sifrhippus gen. nov. is erected for the sister taxon of all other equids, Hyracotherium sandrae Gingerich. Minippus gen. nov., the next more-derived equid clade, is erected for two small equids, M. index Cope and M. jicarillai nov. species. Arenahippus gen. nov. is erected for the next three sequentially more-derived equid taxa, A. grangeri Kitts, A. aemulor Gingerich, and A. pernix Marsh. The genus Xenicohippus, which is the next more-derived equid clade, is redefined to include X. craspedotum Cope. Eohippus Marsh, the next more-derived equid taxon, is resurrected for E. angustidens Cope. Pliolophus, the only early Eocene equid from Europe, is identified as the sister taxon to Protorohippus, a sequence of successively more-derived equid taxa consisting of P. montanum Wortman and P. venticolum Cope. Protorohippus venticolum is identified as the sister taxon of Orohippus. Systemodon Cope is resurrected for S. tapirinum Cope. This taxon has historically been placed within Hyracotherium yet this analysis allies it with Cymbalophus near the base of the perissodactyl radiation. © 2002 The Linnean Society of London. Zoological Journal of the Linnean Society, 134, 141-256.
Skimming the rest of his monograph, I gather he considers Hyracotherium to be polyphyletic and some specimens are more firmly aligned with the tapiromorphs.

Regards,

Darwin's Beagle
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