[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: emu history



I am interested in anything I can learn about the bird. Here in the US there 
doesn't seem to be a lot of information about them, even though there has been 
a growing population of emu ranches and interest in the various products 
created from the emus.

Hmmm... that's interesting. Nothing I've read to date (and I've only been 
researching this for a couple of months, and 98% of that research has been done 
online as books about emus, at least in the public sector, in the US are rare 
to non-existent) said anything about the emu being from a common ancestor with 
the cassowaries. Who was the common ancestor? How did they evolve differently?

I had read in several places that it is believed that the emu has evolved very 
little from its earliest form. One would assume, based on that information and 
what you've said, that the cassowaries probably evolved very little from their 
earliest form. Has that been the case?

One specialist I spoke to suggested that I say that it is believed that the 
emus date back 80 million years ago but that there is more recent research that 
suggests they may only be 45 million years old. Your suggestion is basically 
the same so I think I will take that cue unless there is a further dispute 
about it.

Sorry for the typo on Mr. Cracraft's name. The erroneous spelling is from a few 
websites where I found the information about when the dating of the emu 
happened. When did Mr. Cracraft announce his findings for the dating of the 
emu? Was it '71 or '73?

You forgot about the extinct Tasmanian Emu which is supposed to be a sub-
species of the "mainland" emu. =) Did they ever live on the mainlanda? How did 
they get to Tasmania?

Nancy Cavanaugh <who is sure she has a lot more questions but is falling asleep 
at the computer and needs to go to bed to hopefully not be sick tomorrow>

PS, I am sorry if some of my message is confusing. I am getting sick (hopefully 
not the flu!) so my thought processes are not working right.

-----Original Message-----
From: Ronald Orenstein <ornstn@rogers.com>
> 
> Of course there is no certain way to determine exactly when the modern emu, 
> Dromaius novaehollandiae, first "appeared on earth" -- and, since it 
> obviously evolved from an ancestor which was not quite identical to it, it 
> is not even correct to say that it appeared (as opposed to achieving a 
> certain level of differentiation from its ancestors).  So the first 
> question to ask is, are you interested in when the modern species arose, 
> when the genus arose, the family, or the order?
> 
> There are three ways of getting some sort of answer to these questions: the 
> obvious one, of course, is to come up with a fossil of known age.  Another 
> is to use genetic data to estimate how long ago a species (or higher 
> category) diverged from the common ancestor it shared with its nearest 
> living relative (in this case, with the cassowaries if you are referring to 
> the emu family, as opposed to the living species -- bear in mind that there 
> are two recently extinct emu species, from King Island and Kangaroo 
> Island.)  A third, perhaps more questionable, technique is to look at the 
> history of continental drift.  The argument would go, for example, that the 
> emu lineage -- or at least the emu-cassowary lineage as separate from the 
> lineage is that lead to other large flightless birds such as ostriches -- 
> must be at least as old as the point at which Australia broke away from the 
> land mass of Gondwanaland.  That is where the 45 million-year-old figure 
> comes from, because that is apparently the time at which Australia and 
> Antarctica separated.  However, this does not tell us when emus and 
> cassowaries differentiated from each other, as they both occur in 
> Australia.  Presumably this happened later, but not necessarily as the 
> separation could have occurred before the birds became isolated on the 
> Australian landmass.  Obviously there are none left in Antarctica!
> 
> That said, and noting that Joel's name is "Cracraft", the Handbook of the 
> Birds of the World, Volume one, published in the 1992, notes that the 
> oldest fossils that can be ascribed to the living genus of emus are only 
> some 5000 to 10,000 years old, and belong to the King Island Emu which has 
> since become extinct.  Obviously, emus as a lineage are older than 
> that.  however, the most recent book I have on the subject, a detailed 
> monograph called "Ratites and Tinamous" by SJJF Davies (Oxford, 2002), 
> casts doubt on any of the attempts to determine precisely how old these 
> groups of birds are, and does not suggest a date.
> 
> I would be inclined, given this, not to attempt to come up with an age for 
> the emu family.  All that I think you can really say is that emus and their 
> closest relatives, the cassowaries, have been separated from their nearest 
> relatives ever since Australia drifted away from Antarctica and so, 
> together, must have been around in one form or another for at least 40 to 
> 45 million years.
> 
> 
> --
> Ronald I. Orenstein                           Phone: (905) 820-7886
> International Wildlife Coalition              Fax/Modem: (905) 569-0116
> 1825 Shady Creek Court
> Mississauga, Ontario, Canada L5L 3W2          mailto:ornstn@rogers.com
>