Q: Why don't cows, sheep, and goats have their top front teeth? (Shannon, World)
A veterinarian bares a goat's dental pad. Photo courtesy of Melissa Rouge of Colorado State University, used with permission.
A: Not just cattle, sheep and goats, but all 192 living species of ruminants — antelopes, giraffes, pronghorn antelopes, deer, musk deer and tiny chevrotains (mouse deer) — lack top incisors. All these animals have a tough dental pad below their top lip instead of front teeth, and a huge gap between the dental pad and the back teeth.
This dental arrangement helps ruminants gather great quantities of grass and fibrous plants. A cow, for example, wraps her long, rough, dexterous tongue around a big wad of grasses, pulls the green stuff into her mouth, fits the wad into the huge gap (between front pad and back teeth), pinches the strands about six inches from the ground between her bottom incisors and her top dental pad, and, by swinging her head, neatly cuts a big swath of grass.
Cow's jawTooth and jaw structure of cattle: a top dental pad instead of top front teeth and a large gap between the pad and the back molars. Drawing courtesy of Sarah Williams, Virginia Cooperative Extension; drawing modified by the author.
Ruminants, you may recall, have a complicated four-chambered stomach that allows them to regurgitate their food as a cud, grind it more thoroughly at their leisure, and, thereby, get a maximum amount of nutrients from a given amount of food.
But ruminants' early ancestors did have all their teeth, just as pigs do now. The earliest known ruminant (Archaeomeryx) looked like a small deer, about hare sized, but had fully functioning front incisors. They lived about 50 million years ago (during the Eocene epoch) in what is now Mongolia. Over the eons, the creatures lost their front teeth. Interestingly, these deer are still around today, dwelling in forests by streams of Southeast Asia and West Africa — little changed from their ancestral form.
Speculating why the ancestral ruminants lost their top cutting teeth (replacing them with a tough dental pad) takes us into unmapped country.
"I think nobody has a good answer," says paleontologist Christine Janis, professor at Brown University. But her "best guess" is "it has something to do with ruminants being highly selective feeders." They are picky about what they jam in their stomachs, because whatever they eat goes through many lengthy, digestive processes. They choose food of value, where they get their money's worth for the time investment.
Moreover, ruminants use their tongues to select good food (leaves, for example, over stems), and so treat their tongues with respect. "I can imagine natural selection acting on loss of the upper teeth, so as to not bite and injure their tongue," says Janis. "However, that's pure speculation, not a testable hypothesis."
Her guess makes sense, though, because camels select food with tongues, have a three-chambered stomach, regurgitate their food and chew their cud. Thus, they almost qualify as ruminants. Moreover, they have some reduction of upper incisors. Horses — on the other hand, who use lips, not tongues, to select food — have big, fat, front teeth.
. 
I've been meaning to ask, how many girls and boys do you already have? Is DH out numbered? TJ still has reflux :worry: at least its not projectile.
upsidedow ) sucks. It freezes lettuce and melts ice cream. The drawers are so skee-wom-pus and dont close and open smoothly.
Once they start running around at school they should be fine. 
Ethan said it was money and that would make sense since I had found money in his mouth many times yesterday. 
