And animals in the wild are much the same- all things being equal they will choose the most nutritious, calorie rich option available. And during times of limited resources/low plant productivity herbivores will fall back on some interesting food choices to make it through until better times. One of these fallback food stuffs for many herbivores is lichen.
Of course lichen are all kinds of cool and are generally overlooked in many ecological schemes. They may actually compromise about 8% of the earths vegetative cover, especially in desert, alpine, and arctic/taiga environments. Not actually a plant though, they are a symbiosis between a cyanobacterial alga and the host fungi. This symbiosis might be a little too fairy-tale as it is becoming evident that the fungi captures and imprisons the free living alga for it's own vested interests. Fruticose lichen are generally arboreal. One species common in my area is
If your interest is perked go read this nice overview.
Little appreciated and unheralded as a food lichen is surprisingly important as a winter browse for many types of deer, rodents, primates, and ruminants. In the article linked above the importance of lichens as a winter browse for several ungulates such as black tailed deer, mule deer, pronghorn, and moose is documented. Flying squirrels and reindeer are well documented as lichen consumers. Arboreal lichens prove especially useful browse in winter. In some instances lichen compose well over 50% of an animals diet in the winter. Since lichen are slow growing and the beard type arboreal lichens are so crucial this of course has implications for protection of old growth stands for winter forage. Although generally considered inferior to new plant growth lichen offers abundant carbs, some protein, and is actually digested fairly easily.
And as anyone who watches the numerous survivor shows on TV knows humans do consume lichens, usually boiled- although like their cousins the mushrooms poisonous species exist and unless you absolutely know what you are doing DO NOT EAT LICHENS. They posses a suite of little known and often carcinogenic compounds. Lichen are also notorious for absorbing radiation from the environment and other toxic nasties, DO NOT EAT. One of the more interesting lichen based dishes I discovered is called "stomach ice cream". Consumed by several northern tribes in the taiga it consists of fermented lichen in the stomach of a caribou/reindeer and stuffed with fish eggs. Yum!!!
It should also be mentioned that lichen is not always simply a fall back food. Alpine Ibex will go to great lengths to graze on some nice crustose lichens (and rock salt).
OK so I have made my case that lichen are important food stuffs in extant ecosystems- but what about in the Mesozoic- did dinosaurs eat lichens? And in what sort of habitats did they offer the most benefit as "fall back" food sources?
I think in addition to alpine habitats (which we have no record of and probably never will due to upland sedimentation/geologic characteristics) two uniquely Mesozoic habitats may have offered lichen benefits to herbivorous dinosaurs. And these two habitats would have been; xeric habitats, especially the equatorial arid belt; and high latitude forests.
Some models predict that the equatorial arid belt was simply too hot to support higher plants but these models may also be inaccurate. Regardless there was significant aridity during much of the Mesozoic and lichens, in addition to biological soil crusts, were likely important components of these ecosystems as they are now. I have even went so far as to speculate that the unique oral equipment of some dinosaurs such as Nigersaurus tacqueti were adapted to
scraping up lichens/soil crusts/moss/lycopsids in xeric habitats.
|Lichen Hill. Karoo S. Africa
|Lichen desert. Namib, Africa
|National Park Chile. Oliver Gluch
Fruticose Lichen Photos
Lichen Use by Wildlife in North America
Lichens Mysterious and Important
Nothofagus: Relics From Gondwana
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