Crappie and mastodon

Crappies and mastodons shared the same habitat.  Crappies are primarily a lake fish, preferring clear still water where they prey on small minnows and insects.  Mastodons often waded into lakes to feed upon submerged aquatic plants.  Perhaps they even aided crappies by forcing minnows away from the cover of underwater vegetation into the open to be picked off by schools of crappie.  Of course, mastodons weren’t as tied to the water as crappies and could travel overland whenever they desired.

Black crappie (Pomoxis nigromaculatus).  A beautiful fish and tasty too.  I once had a fish dinner of bass and crappie.  The bass were meatier, but the crappie were sweeter and better tasting.

Kurt Hamlin, a curator at the Milwaukee Museum, was lucky enough to find fur on a mastodon specimen.  The fur resembled that found on river otters and beavers, so we know mastodons spent a lot of time in the water.

River otter (Lutra canadensis) pelt.  River otter fur is water proof and dries quickly.  Mastodon fur was similar.

Although these two different species shared the same habitat, the fossil remains of mastodon and crappie have been found together at only 1 locality–The Charles Adams Mastodon Site in Livingston County, Michigan.  It was a lake deposit also containing fossils of meadow vole, 1300 snail shells, 500 freshwater clam shells, and bones of white sucker fish.  In Georgia mastodon fossils have also been found associated with fish remains, but not crappie.  An alluvial deposit in Little Kettle Creek contained bones of channel catfish along with mastodon.  The  deposit in Kingston Saltpeter Cave in Bartow County contained over 500 fish bones in addition to a mastodon fossil. Here, predatory birds brought  fish from the nearby Ashpole Creek, a tributary of the Etowah River.  They included gar, pickerel, channel catfish, bullheads, sucker fish, chubsuckers, largemouth bass, and unidentified sunfish.  Coastal fossil sites often have marine species of fish as well as mastodon.

Overall, fish populations during the Pleistocene were much higher than those of today’s waters.  Then the rivers were undammed, unpolluted, and unfished by men.  But in what’s now Georgia crappie populations were probably an exception.  They thrive in modern artificial reservoirs formed behind the numerous hydroelectric dams.  Suitable habitat during the Pleistocene was temporary and sporadic.  Oxbow lakes were plentiful during interstaidals and interglacials.  Cut off channels were common during stadials.  But large lakes akin to modern day reservoirs were nonexistent.  Instead, crappies relied on favorable habitats that constantly changed with the evershifting river patterns.  They can live in rivers where water flow is obstructed and forms pools.  Lower water levels with still channels, and higher water levels with wide bends that form slow moving water both provide favorable habitat.  Crappies could also inhabit large beaver ponds.  But the constantly changing conditions probably made crappie numbers fluctuate much more than they do in today’s reservoirs.

Centrarchid Evolution

An evolutionary tree of the centrarchid family of fishes as proposed by some scientists.

 The centrarchid family of fish includes sunfish, crappie, and bass (though not white bass, striped bass, and sea bass which are in completely different families).  The opportunity for speciation occurs often among this family because populations of fish get isolated when connecting streams run dry or become obstructed.  This makes the centrarchid family an excellent one for evolutionary scientists to study.  Scientists can look at rates of genetic divergence between closely related species and estimate the length of time it has taken since speciation occurred from a mutually ancestral species.  They call this a speciation clock. Many species of centrarchids hybridize but genetic compatibility decreases with time since speciation occurred.  One study found that hybrid embryo viablity declines 3% per million years of separation.

Here’s a list of centrarchid species which are strictly an American family of fish.  Note:  Some scientists recognize 33 species and 7 genera; others recognize 31 species and 9 genera.

Mud sunfish–Acantharchus pomotis

Shadow bass–Amploplites aribmarus

Roanoke bass–A. cavifrons

Ozark Bass–A. constellatus

Rock Bass–A.  rupestris

Sacramento perch–A. choplites

Blackbanded sunfish–Ennearanthus gloriousus

Flier–Centrarchus macropterus

Redbreast Sunfish–Lepomis auridus

Green sunfish–L. cyanellos

Pumpkinseed sunfish–L. gibbosus

Orange spotted sunfish–L. humili

Warmouth–L. gulobus

Bluegill–L. marochirus

Dollar sunfish–L. marginatus

Longear sunfish–L. megalatis

Redear sunfish–L. microlophus

Red spotted sunfish–L. miniatus

Spotted sunfish–L. punctatus

Bantam sunfish–L. symmetricus

Redeye or Coosa Bass–Micropterus coosae

Spotted Bass–Micropterus punctatus

Largemouth Bass–Micropterus salmonoides

Shoal Bass–M. cataractus

Guadalupe bass–M. treculi

White crappie–Pomoxis annularis

Black crappie–P. nigromaculutus

Redeye bass

A redeye bass.

In my blog entry of a few weeks ago about the food I would eat, if I could live in Georgia 36,000 BP, I mentioned smallmouth bass as a fish I might find in my fish traps on the Broad River.  At the time of European colonization of North America smallmouth (aka spotted) bass only occurred in extreme northern Georgia.  It did not naturally occur in the Broad River, though it has since been introduced.  During the Pleistocene, smallmouth bass may have ranged further south, but maybe not.  Instead, redeye bass, a closely related species, did occur on the Broad River.  Redeye bass and smallmouth bass probably evolved from a common ancestor that diverged due to the geographical separation of the watersheds where this common ancestor lived.  So, I believe I would find redeye bass in my Pleistocene fish traps in the Broad River, and probably not smallmouth.

Reference:

Bolnick, Daniel; and Thomas Neal

“Tempo of Hybrid Inviability in Centrachid Fish (Telestei: Centrarchae)”

Evolution 59 (8) Augusts 2005

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5 Responses to “Crappie and mastodon”

  1. jamesrobertsmith Says:

    Have any studies been done as to the population densities for Mammoth versus Mastodon? Was one more numerous than the other? One more widespread? One more specialized than the other?

  2. markgelbart Says:

    I don’t think any scientist has ever counted up every mastodon fossil and every mammoth fossil and compared how numerous one was compared to the other. That would be a rather dubious method anyway. Mastodons lived near water, so they would be more likely to become fossilized or found as fossils than mammoths would be.

    Archaeologists noticed that mammoth fossils were more common in western North America and mastodon fossils were more common in eastern North America, but mastodon fossils have been found freqeuntly out west and mammoth fossils are fairly common in the east. Woodlands were more widespread in the east and grasslands more common in the west.

    Scientists have long known the differences in teeth between mastodons and mammoths. Based on tooth structure, they know the former were browsers that mainly ate twigs and soft plants; the latter were grazers that mainly ate course grass.

    Recent studies of bone chemistry back this up. The chemical make up of mastodon bones supports the belief that they mainly browsed on forest and aquatic vegetation, while the chemical composition of mammoth bone shows they ate mostly grass. Plus, scientists have coprolites of both, and they’re consistent with these studies.

    There was a definite habitat differentiation between the two. Mastodons liked river and stream valleys and forests; mammoths preferred upland grasslands.

  3. jamesrobertsmith Says:

    Forgot to mention…I’m trying to plan a hike onto Grandfather Mountain where there is said to be direct evidence of Pleistocene glaciation on the peak. It’s almost 6,000 feet in elevation. If any mountain in NC ever had glaciers on it, I’d argue that Grandfather Mountain (aka Tanawha) is the most likely candidate. One of my hiking pals knows the specific part of the mountain that shows this evidence. It’s known locally as “the Boone Bowl”. He’s hiked there and agrees that it was produced by a local glacier. I’ve seen glacial cirque in New England (Mount Washington in New Hampshire and Katahdin in Maine) so I hope to be able to see if it looks likely.

  4. markgelbart Says:

    I didn’t know a glacier formed that far south. I think I read somewhere that scientists don’t believe any of the southern mountains of the Appalachians were covered by glaciers. Wouldn’t be surprising if an isolated high peak was though. The glacier did push as far south as northern Kentucky durin the Illinois Ice Age (~230,000-~132,000 BP). Maybe the glacier dates to then. The entire Ohio River owes its course to the glacier of that ice age.

  5. jamesrobertsmith Says:

    Yeah, this would have been a localized glacier. Something big enough to carve glacial cirques and leave glacial moraines. I think Grandfather/Tanawha would have been just high enough and just far enough north to have calved a small glacier.

    I also read a paper some years back that argued that there had also been localized glaciers on and around Mount Rogers in southwest Virginia. Again, the peak is relatively high (almost 5,800 feet) and is even farther north than Tanawha. I’ve hiked all around Rogers, though, and have never seen anything that looks like it might be an old overgrown glacial cirque. The paper mentioned certain types of boulders and polished rock that are normally associated with glaciers.

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