What are mesocarnivore/hypocarnivore/omnivore?

[snorkack]

Checking the Wikipedia articles of mesocarnivores and hypocarnivores...
https://en.wikipedia.org/wiki/Mesocarnivore
Supposed definition:
A mesocarnivore is an animal whose diet consists of 50–70% meat with the balance consisting of non-vertebrate foods which may include insects, fungi, fruits, other plant material and any food that is available to them.[1]
Van Valkenburgh, Blaire (2007). "Déjà vu: the evolution of feeding morphologies in the Carnivora". Integrative and Comparative Biology. 47 (1): 147–163.

And a concluding claim:
Mesocarnivores are from a large family group of mammalian carnivores and vary from small to medium sized, which are less than fifteen kilograms.[2]Gary W. Roemer, MattheSw E. Gompper, Blaire Van Valkenburgh, "The Ecological Role of the Mammalian Mesocarnivore", BioScience, Volume 59, Issue 2, February 2009, Pages 165–173
However, hypocarnivores are defined:
A hypocarnivore is an animal that consumes less than 30% meat for its diet, the majority of which consists of fungi, fruits, and other plant material.[1] Van Valkenburgh, B. "Déjà vu: The evolution of feeding morphologies in the Carnivora"

Then questions:

1. Is an animal that eats 30% to 50% meat a hypocarnivore, mesocarnivore or neither?
2. What distinguishes an omnivore from a hypocarnivore?
3. Of bears, polar bear is a hypercarnivore. Some other bears are hypocarnivores, and panda is a herbivore. Do any bears exist that are mesocarnivores?

 

[Drakkith]

From Valkenburgh's article you referenced (underlining mine):

Such studies allow the reconstruction of feeding habits of extinct species and have documented an early diversification among large (>7 kg) carnivorans into three fundamental dietary categories: hypercarnivorous (diet >70% vertebrates), mesocarnivorous (diet is 50–70% meat, with the balance made up of nonvertebrate foods), and hypocarnivorous (diet >70% nonvertebrate foods) (Van Valkenburgh 1988b; Wang et al. 1999; Wesley-Hunt 2005). These categories are not entirely discrete and grade into one another to some extent, but are useful for broad analyses.

1. If it helps, you could simply extend each label 10% and call anything eating less than 40% meat a hypocarnivore, and anything eating 40%-70% a mesocarnivore.

2. It should be noted that Valkenburgh is writing specifically about mammals of the Carnivora order, not about feeding types in general. It is entirely possible that different fields have different classifications, so an omnivore might still be classified as hypocarnivorous. Or, to put it another way, a member of the Carnivora order that Valkenburgh labels as hypocarnivorous might also be considered an omnivore.

3. No idea.

 

[dextercioby]

I don't understand the relevance of weight (body mass) in this categorization. I think it's also not clear whether the standard terminology (carnivore, omnivore) fully overlaps the hypo, meso, hyper categories. Omnivores can survive without meat, carnivores can't. A pet dog is an omnivore, or a carnivore? You wish to have him healthy, so you feed him >70% meat, but dog food processing is hard to label into percentage animal, percentage plant.
What I sadly discovered a week ago is that cats, being obligate carnivores, must consume cat food with little to no carbs, otherwise, they become diabetic, even easier than humans who can drink coke/pepsi and eat cookies as much as they want and still not beat the glucose/fructose clock (me).

Returning: choose some 40/70 or 35/70 or 30/70 boundaries for this hypo, meso, hyper. Label every living or extinct mammal into these 3 categories. Science job done. Go now to the public. They only know of herbivore, omnivore, carnivore. You tell them: well, you can still do this, but it's not so helpful to use these ancient labels. We only have herbivores, whose digestive system cannot process meat-based fats and proteins, and we have carnivores (and we also have pigs, which humans grow as herbivores, but mfs will eat meat faster than lions, if fed by chance). The latter can be divided into 3 segments (or 4), hypo, meso, hyper and possibly obligate. But the split is not so sharp and the splitting into hypo and meso is clearly irrelevant, but we like it and we will keep it. So why bother?

 

[Drakkith]

I don't understand the relevance of weight (body mass) in this categorization.

The scientist who wrote the article primarily studied animals in Carnivora with a mass of 7 kg or greater since these are much better represented in the fossil record than smaller animals:

I then document some of the most striking examples of convergence in feeding morphology within past and present terrestrial carnivorans, highlighting both the similarities and differences in form. The emphasis is on terrestrial species larger than about 7 kg in mass as the fossil record is much better for this size class.

 

[dextercioby]

Ok, all good. But he could have chosen 8 kg, or 10 to make it round. Anyways, to add a bit on the previous message, what would be an example of hypercarnivore wild mammal which would not be an obligate carnivore?

 

[snorkack]

Tooth morphology, for example, fossilizes. Enzyme composition - missing or short supply enzymes - does not.
Can the actual meat percentage in fossil´s food be measured? Like from isotope composition of the bones?

 

[Drakkith]

Can the actual meat percentage in fossil´s food be measured? Like from isotope composition of the bones?

Good question. A quick skim of the article above doesn't seem to show how this was measured. I assume it was based on dental and jaw structures referenced to existing animals. But that's really just a guess.