"... Why do cows wear bells? Their horns don't work!" Some cows have horns."
Seriously, are horns on a cow a vestigial appendage?
Black and white rhinoceros ... Usually the front horn is longer than the rear. ... black rhinos seem to like twigs and they will use the pointed ...
Then the cow will attack the bull and butt him in ...
Black and white rhinoceros
I can't really find any information on Google if cows (moo moo) use their horns for anything real, the cows I grew up around didn't that I know of -- and there's nothing there saying horns are vestigial on cows.
I looked up cow evolution and remembered that cows were bovines, and looked further and found out that the scientific latin name for bovines is "bovidae," which gives me access to all the scientific stuff on the web, so I googled: bovidae evolution fossil*
I also did a google image search just under bovidae.
Here are pics of the earliest known bovine skull and skeleton, apparently on display at two museums:
Other ancient bovine fossils consist of the usual assorted teeth and jawbones, the above apparently being some of the best preserved fossils of more than just teeth and jawbones.
Short wikipedia encyclopedic entry with a few paragraphs on bovine evolution:
More extensive and footnoted article on the same topic, including some DNA comparison testing among bovine species!
"The conservative nuclear DNA data were remarkably effective in resolving associations among bovid subfamilies, which had a rapid radiation dating back to approximately 23 MYA. All analyses supported the monophyly of the Bovinae (cow, nilgai, and kudu clade) as a sister lineage to the remaining bovid subfamilies, and the data convincingly suggest that the subfamilies Alcelaphinae (hartebeest, tsessebe, and wildebeest group) and Hippotraginae (roan, sable, and gemsbok clade) share a close evolutionary relationship and together form a sister clade to the more primitive Caprinae (represented by sheep, goat, and muskox). The problematic Reduncinae (waterbuck, reedbuck) seem to be the earliest-diverging group of the Caprinae/Alcelaphinae/Hippotraginae clade, whereas the Antilopinae (gazelle and dwarf antelope clade) were always polyphyletic. The sequence data suggest that the initial diversification of the Bovidae took place in Eurasia and that lineages such as the Cephalophinae and other enigmatic taxa (impala, suni, and klipspringer) most likely originated, more or less contemporaneously, in Africa.
"Evolution within the family Bovidae (cow, sheep, and antelope) is characterized by global immigrations, adaptive radiations, and mass extinctions which, in concert, gave rise to the 49 extant genera and more than 140 species known today. The majority of these species are endemic to the African continent, and the complex evolution of the group was molded by a wide variety of mechanisms and natural events, including temperature adaptation, feeding ecology, vegetation physiognomy, rifting, and climatic fluctuations (Kingdon 1989 ). The oldest bovid fossils are attributable to the subfamily Bovinae and are known from France and sub-Saharan Africa, where the group evidently first appeared approximately 23 MYA (Vrba 1985 ; Kingdon 1989). "
--Molecular Insights into the Evolution of the Family Bovidae: A Nuclear DNA Perspective By Conrad A. Matthee and Scott K. Davis Department of Zoology, University of Stellenbosch, Stellenbosch, South Africa Department of Animal Science, Texas A and M University [Molecular Biology and Evolution 18:1220-1230 (2001) © 2001 Society for Molecular Biology and Evolution]
I also discovered that the entire cow genome was recently sequenced:
And while cruising the web I also ran across a new study (Jan. 2005!) that compared segements of bat DNA taken from different species around the world. Bats are interesting because creationists used to make "the impossibility of cetacean evolution" their centerpiece "problem" for evolution, but now they are making "the impossibility of bat evolution" their centerpiece problem because too many cetacean intermediates fossils are now known, and because the fossil record of bat evolution remains sparser than that of cetacean evolution. Bats of course are tiny and thin-boned and generally live in places with plenty of insects to feed on, since they eat a lot of insects per their weight (and hence when bats die there are also plenty of insects and other organisms around where they live to make sure their own bones are eaten or break down quickly), so bats didn't leave a great fossil record. (While the fossil record of sea-animals remains better preserved, for many reasons.) Only after bat evolution had already taken off (pardon the pun) and bats began reproducing in large numbers and flying around, did their odds increase of some of them being fossilized and also later found. For instance there's a well preserved bat fossil found in the Greenriver fossil lake formations in the U.S. Anyway, the new study compared segments of the DNA of different bat species round the world, and "played back" the DNA similarities and differences, like tracing back old chain letters to their most common and most likely shared source. The DNA study showed that all bats (including the large fruit-eating bats of the tropics) evolved from tiny insect-eating bats in North America.
I guess Noah's ark kept moving around, letting the first bats disembark in North America, and the first bovidae disembark in Eurasia, and the Noah and his sons disembark in Africa, and the first perching birds disembark in Australia/New Zealand. (Comparing segments of DNA from perching bird species round the world lead recently to the conclusion that Australia/New Zealand was most likely where all perching birds first evolved.)
Speaking again of bat evolution, I read recently about a developmental gene being discovered that rats and bats share, that has to do with prolonged finger growth in the womb and how the skin remains between the longer fingers in the rats they experimented on. I also read about the discovery, a few years ago, of the fossil of a rat-like creature whose ankle bone could flex like a bat's for upside-down hanging.
I guess the creationists are batting zero (pardon the pun) on trying to disprove evolution.