2001. Proceedings of the Academy of Science 1 10:151-166

PALAEOECOLOGY OF A NORTHEAST INDIANA WETLAND HARBORING REMAINS OF THE GIANT (CASTOROIDES OHIOENSIS)

Anthony L. Swinehart: Department of Biology, Hillsdale College, Hillsdale, Michigan 49242

Ronald L. Richards: Indiana State Museum, 202 North Alabama Street, Indianapolis, Indiana 46204

ABSTRACT. Recovery of a femur of an adult Pleistocene giant beaver (Castoroides ohioensis) from a cornfield in Whitley County, Indiana, prompted an analysis of the palaeoecology of the site. Inspection of historic maps and more recent United States Geological Survey (USGS) topographic maps facilitated reconstruction of the pre-disturbance physiography of the site. What is currently a ditched agricultural area was once an extensive shallow lake associated with Spring Creek, which drains into the Eel River. The lake occurred on the interlobate Packerton Moraine created during Wisconsin glaciation. Analysis of subfossils taken from the deepest limnogenic sediments (170 cm) to the upper limit of the peat layer (60 cm) indicates that the lake was eutrophic, mineral-rich, and surrounded by boreal forest for much of its existence. A radiocarbon date of 1 1,240 ± 80 yr BP, taken within 10 cm of the upper limit of limnogenic sediments, suggests that the lake was extinguished at an early time, perhaps before the demise of the boreal forest. The lake was succeeded by an emergent marsh and finally a peat-forming wetland dominated by bulrushes (Scirpus spp.). Anthropogenic re-routing of Spring Creek and other ditching has desiccated the wetland, and only farmland remains. Thirteen plant and 16 species (mostly mollusks) were recovered from the site. The gastropod assemblage was similar to other late-glacial and marls with only a few exceptions. One species recorded in the deposit, Lymnaea haldemanni, is no longer extant in Indiana. Helicodiscus parellelus and Uniomerus tetralasmus are reported as new subfossil records for the region. The giant beaver remains are presumed to have been deposited circa 10,000 yr BP. the same time that the species is thought to have gone extinct.

Keywords: Castoroides, Gastropoda, Indiana, lakes, macrofossil, paleoecology, peatland, Pleistocene

The giant beaver, the largest of the suggest that the incisors were not efficient in

North American Pleistocene, is surrounded by cutting trees, and that the giant beaver did not, controversy. Much of this controversy in- therefore, construct dams (Powell 1948; Stir- volves whether or not the Pleistocene giant ton 1965; Holman 1975, 1995; Kurten & An- beaver (Castoro ides oh ioens is) shared feeding derson 1980; McDonald 1994). Furthermore, and behavioral characteristics with the modern Hay (1912) had long before noted that the beaver {Castor). Castoroides ohioensis at- "pinching" of the internal pterygoid plate and tained lengths of 1.9-2.2 m (6.2-7.2 feet) and other alterations of the skull had been an ac- weights of 90-125 kg (200-275 lbs) (Mc- commodation for the insertion of large inter- Donald 1994). Early studies concluded that nal pterygoid muscles into the pterygoid fos- the giant beaver felled trees and built dams as sae, rather than a cavity for air reserves, does the modern beaver (e.g., Moore 1890; Finally, Holman (1975, 1995) related that Hay 1912; Cahn 1932). Moreover, the medial Castoroides had a smaller brain with a "pinching" of the internal pterygoid plate of smoother outer surface than in Castor, sug- the skull, which constricts the posterior end of gesting that Castoroides had much less com- the nasal passage into upper and lower vents plex behavior patterns and social interactions

(Moore 1890; Hay 1912; Stirton 1965), was than the latter. thought by Stirton (1965) to offer a greater air There is a general agreement that Casto- reserve for the extended underwater activity roides thrived in lakes and ponds that were that is so common in Castor. Later studies bordered by swamps (Powell 1948; Stirton

151 152 PROCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE

1965; Saunders 1977; Kurten & Anderson Blatchley & Ashley's (1901) treatise on the 1980; Harington 1986; Holman 1995) as well lakes and marl deposits of the northern part as marsh habitats (Holman 1975, 1995). The of the State). giant beaver is thought to have co-existed The present paper reports on macroscopic alongside the American mastodont, Mammut subfossils recovered from the Wilkinson Giant americanum (Moore 1890; Powell 1948; Gra- Beaver Locality in northeast Indiana. The ob- ham et al. 1983) and the modern beaver (Har- jectives are to: 1) reconstruct the palaeoenvi- ington 1986; McDonald 1994). Most authors ronment of the Wilkinson giant beaver using believe that Castoroides was a good swimmer, macroscopic subfossils as indicators, 2) doc- though was clumsy on land. Its habits have ument, using subfossils and stratigraphy, the been envisioned more as those of the marsh- biological and limnological changes of the dwelling muskrat (Stirton 1965; Kurten & An- wetland from time of creation to present, 3) derson 1980), as a giant "swamp rat" moving compare the subfossils of the Wilkinson Site along wide trails through the coarse vegeta- to other post-glacial wetland deposits in the tion of the marshy shores of a lake or across southern region, and 4) discuss the swampy floodplain of a glacial river (Pow- the presence or absence of modern analogues ell 1948), or as a "large, clumsy water hog," of the Wilkinson palaeoenvironment in the meandering about in marshes and ponds feed- context of potential Castoroides habitat. ing upon aquatic vegetation (Holman 1975, STUDY AREA 1995). It is thought to have fed upon coarse leaves, the roots of sedges, cattails, and other The Wilkinson Locality is located 2.7 miles vegetation (Powell 1948; McDonald 1994). SE of Larwill, Whitley County, Indiana Many authors believe that a reduction or loss (NWQ, SWQ, SWQ, NEQ, Sec." 14, T31N, of its preferred habitat at the end of the Pleis- R8E, Lorane Quad). The area is situated in an tocene and perhaps its overspecialization, in- outwash channel associated with the interlo- cluding the inability to disperse readily and to bate Packerton Moraine of late-Wisconsin build dams, contributed to its extinction (Stir- age. The outwash channel is filled with marls, ton 1965; Kurten & Anderson 1980; Haring- mucks, and peats (Gray 1989); and these de- ton 1986; Holman 1995). Direct competition posits are traversed by Spring Creek, which with the modern beaver may also have been flows into the Eel River. The bedrock under- involved (Powell 1948; Kurten & Anderson neath the drift is composed of dolomite and 1980; Holman 1995). limestone (Gray 1987), and the glacial drift is Although Castoroides remains are relative- also limestone-rich. These qualities impart al- ly frequent in Indiana, few of those remains kaline waters throughout the region except for have been recovered in a context that allowed a few rare cases where biological and other detailed interpretation of the rodent's habitat. processes favor acidification.

With the controversy regarding the ' The study site is dominated by limnic and behavior, adaptations, and sudden extinction, wetland sediments created by an extinct, shal- the examination of the plant and animal sub- low lake associated with Spring Creek. The fossils found in association with the giant bea- original course of Spring Creek was changed ver becomes important. Additionally, the pa- as early as the late 1800's by extensive ditch- laeoecology of marl deposits, such as the ing. Subsequent farming has resulted in an

Wilkinson Locality (described herein), in gen- area that bears little resemblance to its aquatic eral, has received less scientific attention than origins. Figure 1 illustrates, based on historic peat deposits. Although several studies have maps, soil surveys, and local topography, been conducted on marl deposits in North what the site might have looked like during America (Baker 1918; Baker 1920; Whittaker pre-settlement times. 1921; Russell 1934; La Rocque 1952; Reyn- olds 1959; Zimmerman 1960; Swinehart METHODS 1995), the study of macroscopic subfossils in Field methods.—Three exploratory trench- Indiana's marl deposits has been almost en- es were dug near the site of the recovery of a tirely neglected. Only a few studies have been Castoroides femur discovered by Monte conducted. (Baker 1920; Swinehart 1995; Wilkinsen, owner of the site. This was done Swinehart & Parker 2000; and a note in initially by backhoe, then with shovel, and fi- SWINEHART & RICHARDS—INDIANA PLEISTOCENE GIANT BEAVER 53

Wilkinson Giant Beaver Locality, Whitley County

Figure 1. —Map showing the location and pre-settlement physiography of the Wilkinson Giant Beaver Locality, Whitley County, Indiana. Shaded area represents the known extent of lake deposits.

nally by trowel as the peat-marl interface (the were recovered by this sampling, suggesting level where the bone was recovered) was the Castoroides femur was a solitary bone not reached. Because no additional elements of associated with the remainder of the skeleton. the giant beaver were located during initial Therefore, a more systematic method was im- trenching, the trenches were then extended plemented to focus on the palaeonvironment further outward, by backhoe, from the original (plant and invertebrate subfossils) of the site. spot of the find (Fig. 2). Water seepage was A one square-meter column of sediment periodically pumped out of the trenches with was removed by trowel at 10 cm intervals a gasoline-powered pump. Initially, randomly from the surface down to the base of the de- selected bulk samples of sediment were posit. The sediments were then transported to washed through a 1.2 mm mesh screen for screening stations for washing, and the result- recovery of vertebrate, mollusk, and plant ing concentrate was bagged for laboratory re- macrofossil materials. However, only plant washing, sorting, and analysis. Water for macrofossils and mollusks, and no vertebrates, screening was provided by pumps, drawing — — —

154 PROCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE from groundwater seepage from a nearby RESULTS sump. Additionally, bulk sediments were tak- Age and stratigraphy.—The depth of 10 depth interval en from each cm and bagged limnic and wetland sediments at the Wilkin- for more detailed, quantitative sampling to be son Locality was 170 cm. The underlying ma- conducted in the laboratory. terial was composed of glacial outwash that Laboratory methods. In the laboratory, — was superseded by a layer of silt (10 cm). all concentrate was re-washed to remove ad- Most of the profile was composed of marl. ditional clay. resulting concen- sand and The The 70-80 cm and 90-100 cm depths had ra- trate was dried and examined under a binoc- diocarbon dates of 11,240 ± 80 yr BP and (10X), ular microscope and the subfossils 11,990 ± 90 yr BP, respectively. The marl lay- 70— were hand sorted. Wood samples from the er was probably produced between 14,000 and 80 and 90-100 depth intervals were sub- cm 10,500 yr BP. It is superseded by 20 cm of mitted to Beta Analytic, Inc., for radiocarbon hemic sedge peat, sand and humus. The l4 dating. Swinehart undertook the study of ( C) amount of coarse gravel (> 4 mm diameter) plant macrofossils, mollusks, and the sediment remained relatively constant throughout the samples, and Richards studied the few verte- profile but increased dramatically near the top brate remains. of the marl stratum before disappearing at the Coarse, and fine gravels, as well medium, initiation of the peat layer (Fig. 2). Smaller as woody and fibrous material from each gravels and sands were present throughout the depth interval were separated, oven-dried, and profile. with a Mettler 360 balance. Or- weighed PE Systematic paleobiology.—Thirteen plant ganic subfossil remains from the bulk-screen- taxa and sixteen animal taxa were recovered ing residues from all depths were identified as macroscopic subfossils (Fig. 2). A brief dis- counted. This analysis supplemental and was cussion of each is presented below. to that conducted on the bulk samples, and resulted in the documentation of infrequent KINGDOM PLANTAE macrofossils not encountered in the sub-sam- Division Bryophyta pling of bulk material. Family Amblystegiaceae sediment sub-sampled in the lab- Bulk was cf. Campylium stellatum (Hedw.) C. oratory for macrofossil analysis. Subsamples Jens. Subfossil Material: Gametophyte frag- 3 of 50 cm volumes from each 10 cm depth ments (INSM 71.12.2901.001-.002; Swine- interval were obtained by water displacement. hart #4B.4.3.16). Occurrence: Occasional in Macrofossil subsamples were dispersed by marl between the depths of 120—140 cm. Hab- gentle agitation in water. clasts of warm Some itat: In open, wet areas of highly alkaline sediment required breakage by hand under- marshes and fens (Crum & Anderson 1980). water. Dispersed sediments were then washed Also found in swamps and on wet banks through a series of sieves, the smallest being (Welch 1957). 0.4 mm mesh. Sieve residue was placed into containers and analyzed immediately. All rec- Division Spermatophyta ognizable macrofossils were identified and Family Pinaceae counted. The resulting macrofossil diagrams Abies balsamea (L.) Mill. Subfossil ma- represent the number of fragments per 50 cm 3 terial: Leaf fragments (INSM 71.12.002901. of bulk sediment (Fig. 2). Seeds and achenes 003). Occurrence: Infrequent in marl, silt, and were identified with the aid of Montgomery outwash between the depths of 100—165 cm. (1977), Martin & Barkely (1961), and Jessen Habitat: Coniferous and mixed forests; occa- (1955); mosses, Crum & Anderson (1981); bi- sionally in cedar swamps, fens, and bogs. valves, Cummings & Mayer (1992); and gas- Comments: Other macroscopic subfossil re- tropods, Harmen & Berg (1971). Macrofossil cords from Indiana include Blueberry Bog, diagrams were generated using Tilia© and Til- Elkhart County (Swinehart & Parker 2000) ia*Graph© computer software (Grimm 1996). and Celery Bog, Tippecanoe County (Swine- Voucher specimens of macrofossils were hart unpubl. data). placed in vials containing 60% ethanol and are Larix laricina (DuRoi) K. Koch. Subfossil held by the first author and by the Indiana material: Leaf scarred portions of twigs State Museum. (INSM 7 1.1 2.00290 1.004-.005). Occurrence: '

SWINEHART & RICHARDS—INDIANA PLEISTOCENE GIANT BEAVER 155

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Occasional in marl and silt between the depths ponds and occasionally quiet waters of of 100—150 cm. Habitat: Swamps, lakeshores streams, in shallow waters less than 2 m (Voss and stream borders, fens, and bogs. Restricted 1972), prefers calcareous waters, often asso- to peatlands in the southern portions of its ciated with Elodea canadensis, Myriophyllum range. Pioneering opportunists, they prefer exalbescens, Najas flexilis, Nuphar advena, open areas where competition for light with Potamogeton natans, P. nodosus, P. pectina- other trees is minimal. Comments: Other mac- tus, P. zosteriformis, and Vallisneria ameri- roscopic subfossil records from Indiana in- cana (Swink & Wilhelm 1994). Comments: clude Prairie Creek Site, Daviess County Other macroscopic subfossil records of the ge- (Whitehead & Jackson n.d.); Blueberry Bog, nus Potamogeton from Indiana include Prairie Elkhart County (Swinehart & Parker 2000); Creek Site, Daviess County (Whitehead & Christensen Mastodont Site, Hancock County Jackson, n.d.); Blueberry Bog and Bristol Fen, (Whitehead et al. 1982); Little Arethusa Bog, Elkhart County (Swinehart 1995; Swinehart & Kosciusko County (Swinehart & Parker Parker 2000); Christensen Mastodont Site, 2000); Binkley Fen and Ropchan Memorial Hancock County (Whitehead et al. 1982); Bog, Steuben County (Swinehart & Parker Burket Bog and Little Arethusa Bog, Kosci- 2000); Celery Bog, Tippecanoe County usko County (Swinehart & Parker 2000); Yost (Swinehart unpubl.); Shafer Mastodont Site, Bog, Lagrange County (Swinehart & Parker Warren County (Swinehart 1996). 2000); Aker Mastodont Site, Marshall County Picea glauca (Moensch) Voss. Subfossil (Swinehart unpubl. data); Dutch Street Bog, material: Leaves and cones (INSM 71.12. Noble County (Swinehart & Parker 2000); 002901.006; Swinehart #4B.4.14.15). Occur- Binkley Fen, Steuben County (Swinehart & rence: Frequent in marl and silt between the Parker 2000); Shafer Mastodont Site, Warren depths of 80—150 cm. Also present in outwash County (Swinehart 1996). at a depth of 165 cm. Habitat: Well-drained Family Najadaceae coniferous swamps, lakeshores and stream- borders, mixed forests (Voss 1972), and oc- Najas flexilis (Willd.) Rostk. & F.W. casionally in peatlands; mostly in boreal cli- Schmidt. Subfossil material: Achenes mates. Extinct in Indiana. Comments: Other (INSM 71.12.002901.012; Swinehart #4B.4. macroscopic subfossil records from Indiana 16.18). Occurrence: Extremely abundant in include Prairie Creek Site, Daviess County marl throughout the 60-130 cm depths. Hab- (Whitehead & Jackson, n.d.); Bristol Fen, Elk- itat: Extremely common in lakes, ponds, hart County (Swinehart 1995); Christensen marshes, sloughs, rivers and streams. Also Mastodont Site, Hancock County (Whitehead found on soft bottoms of open waters in peat- et al. 1982); Shafer Mastodont Site, Warren lands. Commonly associated with Cerato- County (Swinehart 1996); Aker Mastodont phyllum demersum, Elodea canadensis, Lem- Site, Marshall County (Swinehart unpubl. na minor, Myriophyllum exalbescens, data). Potamogeton foliosus, P. natans, P. nodosus, P. pectinatus,, and Vallisneria americana Family Potamogetonaceae (Swink & Wilhelm 1994). Fruits abundantly. Potamogeton praelongus Wulfen. Subfos- Comments: Other macroscopic subfossil re- sil material: Achenes (INSM 71.12.002901. cords of Najas flexilis from Indiana include

008-.01 1). Occurrence: Common in marl be- Blueberry Bog and Bristol Fen in Elkhart tween the depths of 60-100 cm. Habitat: County (Swinehart 1995; Swinehart & Parker Lakes, in water up to 7 m (Voss 1972), in 2000); Christensen Mastodont Site, Hancock clear waters, often associated with Cerato- County (Whitehead et al. 1982); Burket Bog, phyllum demersum, Najas flexilis, Potamoge- Little Chapman Bog, and Kaiser Lake Fen in ton amplifolius, P. gramineus, P. natans, P. Kosciusko County (Swinehart & Parker pectinatus, and P. robbinsii (Swink & Wil- 2000); Yost Bog, Lagrange County (Swinehart helm 1994). & Parker 2000); Aker Mastodont Site, Mar- Potamogeton pusillus L. Subfossil mate- shall County (Swinehart unpubl.); Dutch rial: Achenes (INSM 71.12.002901.035). Oc- Street Bog, Tamarack Bog, and Svoboda Fen currence: Infrequent in marl and silt between in Noble County (Swinehart 1994; Swinehart the depths of 90-150 cm. Habitat: Lakes and & Parker 2000); Binkley Fen and Ropchan — — — — — —

SWINEHART & RICHARDS—INDIANA PLEISTOCENE GIANT BEAVER 157

Memorial Bog in Steuben County (Swinehart ton pectinatus, Spirodela polyrhiza, and Utri- & Parker 2000); and the Shafer Mastodont cularia vulgaris (Swink & Wilhelm 1994). Site, Warren County (Swinehart 1996). Comments: Other macroscopic subfossil re- cords of Brasenia schreberi from Indiana in- Family Cyperaceae clude Blueberry Bog, Elkhart County (Swine- Carex sp. Subfossil material: Aehenes hart & Parker 2000); Yost Bog, Lagrange (INSM 71.12.002901.015). Occurrence: In- County (Swinehart & Parker 2000); Burket frequent in marl and silt in the 90-150 cm Bog, Little Arethusa Bog, and Little Chapman depths. Habitat: Variable. Comments: Other Bog in Kosciusko County (Swinehart & Park- macroscopic subfossil records of Carex from er 2000); Dutch Street Bog and Tamarack Bog Indiana include Prairie Creek Site, Daviess in Noble County (Swinehart 1994; Swinehart County (Whitehead & Jackson, n.d.); Blue- & Parker 2000); and Binkley Fen, Steuben berry Bog, Elkhart County (Swinehart & County (Swinehart & Parker 2000). Parker 2000); Christensen Mastodont Site, Nymphaea tuberosa Paine. Subfossil ma- Hancock County (Whitehead et al. 1982); terial: Seeds (INSM 7 1.1 2.00290 1.022-.024). Burket Bog, Little Chapman Bog, and Kiser Occurrence: Infrequent in marl between the Lake Fen in Kosciusko County (Swinehart & 80-120 cm depths. Habitat: Emergent in qui- Parker 2000); and Ropchan Memorial Bog, et, shallow water of lakes, ponds, rivers and Steuben County (Swinehart & Parker 2000). streams. Often associated with Brasenia Scirpus acutus (Muhl.). Subfossil materi- schreberi, Ceratophyllum demersum, Lemna al: Aehenes (INSM 71.12.002901.016; minor, Najas flexilis, Nuphar advena, and Swinehart #4B.4. 16. 19). Occurrence: Ex- Pontedaria cordata. Comments: Other mac- tremely abundant in marl and sedge peat be- roscopic subfossil records of Nymphaea from tween the depths of 40—110 cm. Habitat: In Indiana include Bristol Fen and Blueberry shallow water or wet areas around lakes, Bog in Elkhart County (Swinehart 1994; ponds, marshes, and flowing waters; also Swinehart & Parker 2000); Burket Bog and found in fens and marl flats. Scirpus validus Little Chapman Bog in Kosciusko County which has a similar achene grows in similar (Swinehart & Parker 2000); and Yost Bog, La- habitats. Comments: Other macroscopic sub- grange County (Swinehart & Parker 2000). fossil records of Scirpus from Indiana include Nuphar advena Ait. Subfossil material: Blueberry Bog, Elkhart County (Swinehart & Seeds (INSM 71.12.002901.025; Swinehart Parker 2000); Christensen Mastodont Site, #4B.4. 16. 17). Occurrence: Frequent in marl Hancock County (Whitehead et al. 1982); between the 80-1 10 cm depths. Habitat: Burket Bog, Little Arethusa Bog, Little Chap- Emergent in quiet waters of lakes, ponds, riv- man Bog, and Kiser Lake Fen in Kosciusko ers, and streams. Often associated with Bra- County (Swinehart & Parker 2000); Yost Bog, senia schreberi, Ceratophyllum demersum, Lagrange County (Swinehart & Parker 2000); Lemna minor, Nymphaea tuberosa and Pon- Aker Mastodont Site, Marshall County tedaria cordata. Comments: Other macro- (Swinehart, unpubl. data); Dutch Street Bog, scopic subfossil records of Brasenia schreberi Noble County (Swinehart & Parker 2000); from Indiana include Bristol Fen, Elkhart and Binkley Fen and Ropchan Memorial Bog County (Swinehart 1994); Christensen Mas- in Steuben County (Swinehart & Parker todont Site, Hancock County (Whitehead et 2000). al. 1982); Burket Bog, Little Arethusa Bog, and Little Chapman Bog in Kosciusko County Family Nymphaeaceae (Swinehart & Parker 2000); Aker Mastodont Brasenia schreberi Gmel. Subfossil ma- Site, Marshall County (Swinehart unpubl.

terial: Seeds (INSM 7 1.1 2.00290 1. 020-.02 1 ). data); Dutch Street Bog and Svoboda Fen in Occurrence: Frequent in marl between the Noble County (Swinehart & Parker 2000); 80-100 cm depths. Habitat: Quiet ponds and and Ropchan Memorial Bog, Steuben County lakes, usually in soft, acid waters (Voss 1972); (Swinehart & Parker 2000). commonly associated with Elodea canadensis, Family Caprifoliaceae Lemna minor, Myriophyllum exalbescens, Nu- phar advena, Nymphaea odorata, Polygonom cf. Triosteum sp. Subfossil material: Seed amphibium, Pontedaria cordata, Potamoge- (INSM 71.12.002901.028). Occurrence: A — — — —

158 PROCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE

single specimen from the 90-100 cm depth. found the species occupying 12% of the total Habitat: Dry or moist woods. Comments: No mollusks in the Fulton County deposit. Swine-

other records are known from Indiana. hart (1995) found it to be abundant in the Elk- KINGDOM ANIMALIA hart County deposit but infrequent in the Kos- ciusko County deposit. It was infrequent Phylum Mollusca throughout the marl layer in the present study. Family Physidae Similar species under the generic synonyms of Physa sayii Tappan. Subfossil material: Galba, Fossaria and Stagnicola are common Shells (INSM #7 1.1 0.2637. 8-.9; Swinehart in Holocene marls of the region (see Baker #4B.5.18.2). Occurrence: In marl; 100-120 1918; La Rocque 1952; La Rocque & Forsy-

cm. Habitat: This species is common to still, the 1957; Reynolds 1959; Zimmerman 1960).

shallow waters (0.3-0.8 m) in open areas. It Goodrich et al. (1944) recognize two subspe- prefers moderate vegetation and well-aerated cies in Indiana's current mollusk fauna, L. hu- water (Zimmerman 1960). While Zimmerman milis modicella and L. humilis rustica, but re- (1960) reports that P. sayii prefers protected cords of their current distribution in the State

areas, Harmen & Berg (1971) found that it are incomplete. was most common in exposed areas. Goodrich Lymnaea haldemani Binney. Subfossil

et al. (1944) note that it can sometimes be material: Shells (INSM #71.10.2637.10; found on wave-battered shores. Comments: Swinehart #4B.5.18.9). Occurrence: In marl Holocene subfossil records from the southern in the 80-90 cm and 100-110 cm depths.

Great Lakes region include; Peoria County, Il- Habitat: Common in shallow waters (0.3-1 m) linois (Baker 1918), Logan County, of larger lakes in abundant vegetation. It pre- (Zimmerman 1960) and Kosciusko County, fers sheltered bays, and is commonly found Indiana (Swinehart & Parker 2000). While on floating vegetation and on the undersides Zimmerman (1960) and Swinehart & Parker of waterlilies (Zimmerman 1960). It has also (2000) found many individuals throughout the been found on rotting Typha leaves (Harmen Ohio and Indiana marl deposits, respectively, & Berg 1971). This species is always found Baker (1918) found only one juvenile in Illi- in limited numbers (Zimmerman 1960). Com- nois. The species was infrequent at the Wil- ments: The only other known Holocene sub- kinson site and restricted to the 100—120 cm fossil record for this species in the southern depths. Physa sayii is presently common in Great Lakes region is from Zimmerman northern Indiana in lakes and occasionally in (1960) from Logan County, Ohio. The fragile

streams (Goodrich et al. 1944). nature of the shell along with the fact that liv- ing specimens of this species are rarely found Family Lymnaeidae in large numbers limits palaeoecological in- Lymnaea cf. L. humilis Say. Subfossil ma- ferences regarding post-glacial populations terial: Shells (INSM #71.10.2637. 1-. 7; and distribution. Shells, always fragmentary, Swinehart #4B.5.18.1). Occurrence: In marl were rare in the Wilkinson deposit. Lymnea between 80-110 cm. Also in silt at 140-150 haldemani is not known to exist presently in cm. Habitat: Harmen & Berg (1971) report Indiana. this species as inhabiting exposed mud flats, Family Planorbidae where they forage between the gravels with their shells partially exposed to the air. Good- Helisoma anceps (Menke). Subfossil ma- rich et al. (1944) also report this species as terial: Shells (INSM #7 1 . 10.2637. 1 1-. 16; inhabiting mud flats. Comments: Subfossil re- Swinehart #4B.5.18.4). Occurrence: Frequent ports for this species in the southern Great in marl and silt between the 60-150 cm Lakes region come from Blatchley & Ashley depths. Habitat: Common in shallow waters

(1901) from marls taken from North Mud (< 1 m) with abundant vegetation. While

Lake, Fulton County, . Indiana; Baker (1920) Reynolds (1959) reports that it prefers ex- from Flat Rock River, Bartholomew County, posed habitats of open lakes, Harmen & Berg

Indiana; Swinehart (1995) from Elkhart Coun- (1971) found it most commonly on inorganic ty, Indiana (misidentified as L. palustris); and substrates in protected areas of ponds as well Swinehart & Parker (2000) from Kosciusko as quiet pools of small streams. Comments: County, Indiana. Blatchley & Ashley (1901) Holocene subfossil records for the southern —— — —

SWINEHART & RICHARDS—INDIANA PLEISTOCENE GIANT BEAVER 159

Great Lakes region include Mahomet, (Swinehart 1995), Kosciusko County, Indiana (Baker 1918), McLean County, Illinois (Baker (Swinehart & Parker 2000), Madison County. 1930), Fulton County, Indiana (Blatchley & Ohio (La Rocque 1952), Ross County, Ohio Ashley 1901), Bartholomew County, Indiana (Reynolds 1959), and Logan County, Ohio (Baker 1920), Elkhart County, Indiana (Zimmerman 1960). Gyraulus parvus!altissi- (Swinehart 1995), Kosciusko County, Indiana mus is usually very abundant in post-glacial (Swinehart & Parker 2000), Ross County, marl deposits. Presently found throughout In- Ohio (Reynolds 1959) and Logan County, diana (Goodrich et al. 1944). Ohio (Baker 1920; Zimmerman 1960). The Promenetus exacuosus (Say). Subfossil species is relatively abundant in the reported material: One shell. Occurrence: In marl, deposits. Probably common in the lake region 100-110 cm. Habitat: Found in quiet waters of Indiana at present. associated with many types of substrates Helisoma campanulata (Say). Subfossil (Zimmerman 1960), but mostly over sand and material: Shells (INSM #71.10.2637. 17.19); mud with thick vegetation (Reynolds 1959).

Swinehart #4B.5. 18.1 1). Occurrence: Fre- La Rocque (1952) reports that it is most com- quent in marl between the 80-130 cm depths. mon in marshy areas or mud flats with pH's Habitat: Occurs in shallow waters of varying from 7-7.6. Similarly, Harmen & Berg (1971) substrates in both protected and wave battered found it most commonly in cattail marshes on areas (Zimmerman 1960). Harmen & Berg the undersides of dead, floating Typha leaves.

(1971) found it mostly on inorganic substrates Dexter (1950) found it abundantly in the Nym- of small marshy lakes. They rarely found it phaea/Pontedaria, Potamogeton, and Deco- associated with other Helisoma spp., with the don zones. It is locally associated with the al- exception of H. anceps and H. trivolvis. Dex- gae Cladophora and Oedogonium (Reynolds ter (1950) found the species to be common in 1959). Zimmerman (1960) reports that P. ex-

Chara/Myriophyllum, NymphaealPon teda ha , acuosus is most common to cooler waters, and and Decodon zones of a basic bog lake in dense vegetation favors the lower tempera-

Ohio. Comments: Holocene subfossil records tures that it seems to prefer. Comments: Ho- for H. campanulata in the southern Great locene subfossil records for P. exacuosus in Lakes region come from Mahomet, Illinois the southern Great Lakes region include Ful- (Baker 1918), Elkhart County, Indiana ton County, Indiana (Blatchley & Ashley (Swinehart 1995), Kosciusko County, Indiana 1901), Madison County, Ohio (La Rocque (Swinehart & Parker 2000), and Logan Coun- 1952), Ross County, Ohio (Reynolds 1959), ty, Ohio (Baker 1920; Zimmerman 1960). Al- and Logan County, Ohio (Baker 1920, Zim- though present throughout many marl depos- merman 1960). Although its presence is not its, this species is usually found in relatively uncommon in Holocene marls, it usually oc- low numbers at any given depth. Presently, H. curs in small numbers. Goodrich et al. (1944) campanulata is common in the lake area of assumed that it is currently found throughout Indiana (Goodrich et al. 1944). Indiana. Gyraulus cf. G. parvus (Say). Subfossil Family Hydrobiidae material: Shells (INSM #7 1.1 0.2637. 20-.26; Swinehart #4B.5.18.7). Occurrence: Abun- Amnicola limosa (Say). Subfossil materi- dant in marl between the depths of 60-140 al: Shells (INSM #71.10.2637'.27-,31; Swine- cm. Rare between 140—165 cm. Habitat: Oc- hart #4B.5.18.13). Occurrence: Abundant in curs in small, shallow, protected waters (Zim- marl between 70-130 cm. Habitat: Common merman 1960), especially in ponds and back- in protected areas of shallow lakes and muddy waters with dense aquatic vegetation (Harmen bays in 0-3 m of water (Zimmerman 1960).

& Berg 1971). Dexter (1950) found it in all It is also found in marshes, ponds, temporary but the Larix and Quercus-Fagus-Ulmus stream pools, creeks and rivers (Harmen & zones of an Ohio peatland. Comments: Rec- Berg 1971). Reynolds (1959) reports that it ords of Holocene subfossils of G. parvuslal- has been found in brackish water as well as tissimus in the southern Great Lakes region freshwater and prefers sandy substrates with include McLean County, Illinois (Baker dense beds of Chara, Potamogeton, Vallis-

1930), Fulton County, Indiana (Blatchley & neria, and Elodea. Dexter (1950) reports it Ashley 1901), Elkhart County, Indiana from the Chara/Myriophyllum, Nymphaeal — — — — —

160 PROCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE

Pontedaria, and Decodon zones. Zimmerman & Parker 2000) and Logan County, Ohio (1960) states the most important limiting fac- (Zimmerman 1960). A similar species V. lew- tor for this species is vegetation (preferably isi was reported for Madison County, Ohio by abundant) and protection from exposure. He La Rocque (1952). Valvata sincera is often also reports that this species can endure long found in association with V. tricarinata but in periods of emergence as long as it remains much fewer numbers. Valvata sincera is pres- moist, but unusually high water temperatures ently common in lakes in northern Indiana. can rapidly exterminate it from a waterbody. Valvata tricarinata (Say). Subfossil ma- Comments: Holocene subfossil records of A. terial: Shells (INSM #71. 10.2637. 35-.41; limosa/leightoni in the southern Great Lakes Swinehart #4B.5.18.8). Occurrence: Abun- region include Mahomet, Illinois (Baker dant in marl between the 60-140 cm depths. 1918), McLean County, Ohio (Baker 1930), Occasional in silt and outwash between 140- Fulton County, Indiana (Blatchley & Ashley 165 cm. Habitat: Inhabits a wide variety of 1901), Bartholomew County, Indiana (Baker conditions but is most common to lakes. Har- 1920), Elkhart County, Indiana (Swinehart men & Berg (1971) report that most speci- 1995), Kosciusko County, Indiana (Swinehart mens from lotic conditions are depauperate.

& Parker 2000), Ross County, Ohio (Reynolds Dexter (1950) found it to be common in the 1959), and Logan County, Ohio (Zimmerman Chara/Myriophyllum, Potamogeton, Nym- 1960). This species is usually very abundant phaea/Pontedaria and Decodon zones. Reyn- in Holocene marl deposits. Presently found olds (1959) reports that the species is partial throughout Indiana, especially in the lake area to firm bottoms and is usually associated with (Goodrich et al. 1944) Oedogonium, Cladophora and Vaucheria. Amnicola lustrica Pilsbry. Subfossil ma- Comments: Holocene subfossils of V. tricar- terial: Shells (INSM #71.10.2637.32-.34; inata in the southern Great Lakes region have Swinehart #4B.5.18.10). Occurrence: Infre- been reported for Urbana, Illinois (Baker quent in marl between the depths of 70-120 1920), Mahomet, Illinois (Baker 1920), Mc- cm. Habitat: This species is less common than Lean County, Illinois (Baker 1930), Barthol-

A. limosa, although it occupies similar habi- omew County, Indiana (Baker 1920) Elkhart tats (Harmen & Berg 1971). It prefers shallow County, Indiana (Swinehart 1995), Kosciusko (0-2 m), highly vegetated waters, where it of- County, Indiana (Swinehart & Parker 2000), ten inhabits filamentous algae (Zimmerman Logan County, Ohio (Baker 1920; Zimmer- 1960). Comments: Holocene records for A. man 1960), and Ross County, Ohio (Reynolds lustrica include Fulton County, Indiana 1959). This is one of the most widely distrib- (Blatchley & Ashley 1901), Bartholomew uted and abundant mollusks of Holocene County, Indiana (Baker 1920), Elkhart Coun- marls. Goodrich et al. (1944) speculate that ty, Indiana (Swinehart 1995), Kosciusko this was one of the first aquatic mollusks to County, Indiana (Swinehart & Parker 2000), re-invade newly deglaciated areas. It presently and Logan County, Ohio (Baker 1920; Zim- occurs throughout Indiana (Goodrich et al. merman 1960). It is presently found in the 1944). lake area of Indiana. Family Endodontidae Family Valvatidae Helicodiscus parallelus (Say). Subfossil material: One shell (Swinehart #4B.5.18.3). Valvata sincera Say. Subfossil material: Occurrence: In marl, 60-70 cm. Habitat: Shells (INSM #71.10.2637.42^.44; Swinehart Goodrich et al. (1944) report this species as #4B.5.18.12). Occurrence: Frequent in marl; being most common in flood plains. Com- 1 10-140 cm. Habitat: This species is reported ments: Accounts of this species in other Ho- as being primarily from deep water (5—6 m), locene marls are not known. Only a single usually below 3 m in depth, of cold lakes with specimen was recovered from the Wilkinson limited vegetation (Zimmerman 1960). Har- site. The species, presently, is distributed men & Berg (1971) found it at a depth of 5 throughout Indiana. m. Comments: Holocene subfossil records for V. sincera include Urbana, Illinois (Baker Family Sphaeridae 1920), Elkhart County, Indiana (Swinehart Pisidium sp. Subfossil material: Shells 1995), Kosciusko County, Indiana (Swinehart (INSM #71.10.2637.45.50; Swinehart #4B.5. — —— — —

SWINEHART & RICHARDS—INDIANA PLEISTOCENE GIANT BEAVER

18.6). Occurrence: Abundant in marl between associations (discussed below) do provide 60-140 cm. Occasional in silt and outwash some insight. Comments: Including the pre- between 140-165 cm. Habitat: Variable. sent, there are 16 credible published records Comments: Common in Holocene marls. for Indiana: Boone County, Jamestown (Hay Sphaerium sp. Subfossil material: Shells 1912); Cass County, Logansport (Martin (INSM #71.1 0.2637.5 1-. 54; Swinehart 1912; Hay 1912); Daviess County, Prairie #4B.5.18.14). Occurrence: Frequent in marl Creek Site (Tomak 1975); Dekalb County, un-

and silt between 60-150 cm. Habitat: Vari- specified locality (Cahn 1932); Grant County, able. Comments: Common in Holocene marls. Fairmount (Hay 1912, 1912b); Hancock County, Greenfield vicinity (Moore 1893); Family Unionidae Hancock County, Christensen mastodont lo- cf. Uniomerus tetralasmus (Say). Subfos- cality (Graham, Holman and Parmalee 1983); sil material: Single specimen (both valves) Madison County, Summitville (Hay 1912); (INSM #71.10.2637.). Occurrence: In marl; Martin County, Shoals (Adams 1946); Miami 60-70 cm. Habitat: Common in ponds, small County, Macy (Hay 1923); Newton County, creeks, and headwaters of larger streams in Mount Ayr (Cahn 1932); Randolph County, mud or sand (Cummings & Mayer 1992). Winchester/Union City (Moore 1890, 1893); May withstand desiccation and, as a result, is St. Joseph County, unspecified locality (En- often found where other mussels are absent gels 1931); Starke County, Grovertown (Hay (Cummings & Mayer 1992). Comments: 1923); Wayne County, Richmond (Moore There are no known Holocene subfossil re- 1893); Whitley, Wilkinson locality (present). cords for this species in the Midwest. Three additional early published records can- not be substantiated: Carroll County (Cope & Phylum Chordata (Subphylum Vertebrata) Wortman 1884); Kosciusko County (Cope & Class Aves Wortman 1884); and Vanderburgh County Order Anseriformes (Collett 1876). Remains from four additional Family Anatidae localities (Madison, Pike, Wayne and Whitley Branta canadensis, ( Goose). Sub- Counties) have not yet been published upon, fossil material: Left ulna, distal 2/5 (INSM and will not be detailed here. #71.3.143.1). Habitat: Historically, the Cana- Castor canadensis, (Beaver). Subfossil da goose was a common migrant and perma- material: Anterior lumbar/posterior thoracic

nent resident of the state. It favors larger bod- vertebra, neural arch only, lacking spine ies of water adjacent to extensive marshland, (INSM # 71.3.143.2). Habitat: In Indiana, the but may be found on nearly any aquatic hab- beaver is most abundant in the lakes, marshes, itat (Mumford & Keller 1984). and streams of the northern part of the state (Mumford & Whitaker 1982). Comments: The Class Mammalia vertebra was from the Thoracic T-l 1 through Order Rodentia T-14, or lumbar L-l or L-2 part of the series. Family A subadult was represented. It is interesting Castoroides ohioensis, (giant beaver). that remains of the modern beaver occurred Subfossil Material: Right femur, lacking me- stratigraphically earlier on the Wilkinson lo- dial condyle area; recovered in two pieces cality than those of the giant beaver. (INSM #71.3.128). Occurrence: Recovered Order Artiodactyla on surface from soils dug from trench. Be- cause trenching extended only down into the Large Artiodactyla, sp. indet. —Subfossil upper few inches of marl, and because the fe- material: Molariform enamel portion (INSM

mur was impacted with mollusk-rich marl, it # 71.3.143.3). Comments: Crown enamel por- is likely that the femur originally occurred tion from hypsodont molariform tooth that in-

within the upper few inches of the marl level, cludes one fossette. The enamel is relatively likely within the 60-70 cm depth. Habitat: unworn.

Because the species is extinct its habitat pref- DISCUSSION erence and habits are not known for sure. However, the functional morphology of skel- Geologic history.—The Wilkinson Site, etal elements (discussed above) and ecological began as a raging meltwater river that depos- 162 PROCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE

ited clean, sorted glacial drift in a channel on vena and Brasenia schreberi, because of the the Packerton Moraine. As the meltwaters shallow depth, probably grew across the entire slowed, a few organic remains indicative of water body. the surrounding forest composition were left As vegetative remains and marl began to behind in the outwash. Finally, stagnation of fill-in the shallower margins of Wilkinson the water resulted in settling of finer materials, Lake, bulrushes (Scirpus validus and Scirpus primarily silts, which blanketed the outwash. acutus) took hold and colonized. While most A shallow lake remained, and an inlet and out- were probably restricted to the marginal wet- let were maintained by Spring Creek, which lands, many probably invaded the shallow wa-

provided ample drainage and oxygen- and nu- ters of the open lake. It is this marsh environ- trient-rich water. It may also have been the ment where the giant beaver lived, died, and source of occasional conifer remains, which was buried. Eventually, the open water filled- indicate a surrounding forest of Picea glauca, in entirely, and a sedge- and bulrush-domi- Abies balsamea and Larix laricina. Infrequent nated wetland remained. Spring Creek main- remains of charred wood suggest occasional tained its presence in the area, and probably

fires. changed course many times as it traversed the The waters feeding Wilkinson Lake were sedge meadow. The creek carried sediments, nearly saturated with bicarbonates brought and sometimes gravels, that were deposited into solution via contact with the characteris- along its course. During spring snowmelt, fast

tically lime-rich glacial till. Because the marl moving waters would carry large gravels into in the basin did not appear to be formed whol- the wetland. This may explain the curious ly- or partially by the calcium carbonate tests abundance of coarse gravel in strictly limnic

of Chara thalli (none were recovered), it can sediments below the marl/peat interface. be assumed that the primary source of the Mollusks.—Based on modern analogues, it

marl precipitate was the uptake of C0 2 by is concluded that the molluscan fauna encoun- phytoplankton and littoral vegetation, or pos- tered in the marls of the Wilkinson site indi- sibly the flow of sub-terranian aquifers into cates the area was once a relatively small, the lake. The shallow nature of the lake meant shallow, wind-sheltered lake with moderate to that the trophogenic zone extended to the sub- heavy vegetation cover and the presence of strate throughout, and carbon dioxide levels muddy or marly flats. The mollusks give some were probably low throughout the water col- indication of the water quality in Wilkinson umn. This would hinder most marl precipi- Lake. Based on ecological amplitudes provid- tates from being brought back into solution as ed by Harmen & Berg (1971) the composition bicarbonate. of the mollusk assemblage at Wilkinson Lake The Castoroides femur occurred at a level suggests that the water probably maintained when coarse gravel had also been deposited, pH values of 7-8.5, alkalinity values of 100- possibly accounting for the stream transport 150 ppm, and dissolved oxygen values of 10- and/or scattering of unburied skeletal remains. 14 ppm. (This was also a period when molluscan re- The decline of mollusks at the end of marl mains were becoming sparse, suggesting at production is attributed to the closure of open least periodic drying of the habitat. A gradual water habitat and the transition to a sedge increase in Najas and Scirpus remains coin- meadow. Given the position and age of the cides with the decrease in mollusks). radiocarbon dates, Wilkinson Lake and the Vegetation.—The early submergent flora subsequent sedge meadow probably extin- was composed of pondweeds such as Pota- guished long before the demise of the boreal mogeton pusillus and Najas flexilis. Both are forest. characteristic of mineral-rich waters. The Na- By far the most abundant mollusks through- jas eventually became extremely abundant, at out the marls of the Wilkinson deposit were least as evidenced by the abundant remains of Valvata tricarinata, Gyraulus parvus, Amni- its achenes in the sediment. While Najas and cola limosa and Pisidium spp. Similarly, additional submergent vegetation, such as Po- Swinehart (1995, unpubl. B.A. thesis, Goshen tamogeton praelongus, became important College) found these species to be the most members of the flora, emergent vegetation be- abundant throughout the Bristol Fen deposit gan to appear. Nymphaea odorata, Nuphar ad- in Elkhart County, Indiana. Reynolds (1959) SWINEHART & RICHARDS—INDIANA PLEISTOCENE GIANT BEAVER I 63

5 3 Estimated number ofmolluscs per 1 .0 x 1 cm ofsediment

50000 100000 150000 200000

3 C 6 o C 'i oo

43545 £ 168,780 c 30764 26761 *-» 20600 Q

3 Figure 3. —Approximate number of mollusk shells per 0. 1 m of bulk sediment at 10 cm intervals throughout the Wilkinson sediment profile.

and Zimmerman (1960) also found Valvata son Lake. Since this species has been noted

tricarinata, A. leightoni {cf. G. limosa) and as preferring deeper water, its demise may Gyraulus altissimus {cf G. parvus) as being have been facilitated early by sediment in-fill- among the most abundant. All of these species ing. The appearance of Helicodiscus paralle- indicate a shallow, weedy lake. The estimated lus at the marl/peat interface is indicative of 3 number of mollusks for each 0. 1 m volume a transition from open water to wetland con- for each depth increased rapidly, then sharply ditions. The near absence of unionid mussels at 120 cm to over 168,000 (Fig. 3) before de- from the deposit may indicate that few fishes creasing again to zero near the 70 cm depth. were present, as unionids usually require fish- The 120 cm depth also had the greatest rich- es as hosts for their parasitic larvae. Corre-

ness of mollusks. It is assumed that the great spondingly, no fish scales or fish bones were abundance and richness of mollusk taxa at this recovered from the deposit. level is a function of ample food and high habitat heterogeneity. As the water became CONCLUSIONS shallower, aquatic vegetation, including algae Early post-glacial lakes.—The discovery (an important food source), probably in- of limnic deposits from lakes and wetlands creased, creating both a variety of food items that have long ago extinguished (so long ago as well as structure (e.g., submergent, floating, that their aquatic origins are often topograph- and emergent vegetation). Continued shallow- ically obscured), not only emphasizes the re- ing of the water and closing of open water ality of classic hydrarch succession (despite

probably reduced light and oxygen levels suf- heated objections to it on the part of many

ficiently to rob many species of suitable food ecologists), it also provides an invaluable ar- and habitat. chive for understanding the palaeoenviron- A few conclusions can be made about con- ments inhabited by extinct organisms. More- ditions in the lake from some of the less abun- over, such deposits help in reconstructing dant species. Valvata sincera dropped out of post-glacial biotic migrations and successions. the assemblage early in the filling of Wilkin- Based on studies of the Wilkinson deposit and 164 PROCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE other similar deposits in the southern Great comparing the ancient habitats to potential

Lakes region, it appears that several species modern analogues. Based on the subfossil of organisms were ubiquitous pioneers to analysis of the Wilkinson sight, functional an- newly created, late-glacial lakes and ponds. alogues of the habitat of the giant beaver have

With regard to plants, members of the existed from the time when it flourished to the Potamogeton as well as Najas flexilis are par- present day. All of the taxa found at the Wil- ticularly common. In marls, the mollusks, Val- kinson site, are extant and common members vata tricarinata, Gyraulus parvus, Amnicola of modern shallow-water wetlands. Only the limosa and Pisidium spp. are almost always boreal conifers have significantly changed present. While these species may be indicative their range and distribution, but even these are of general conditions in a given wetland, it is still found commonly in the northern Mid- the infrequent or scattered taxa that may be of west. Moreover, suitable wetland habitats for more ecological interest because they may in- giant beaver have increased, not decreased, dicate environmental thresholds or ecotones since the retreat of the last glaciers, due in for their respective taxa. Descriptive and nu- large part to colonization of barren outwash merical investigations on the mollusk com- channels by emergent vegetation as well as munities of the lakes and wetlands of Indiana ecological succession and consequent in-fill- are few and insufficient not only in terms of ing of deeper water bodies. At the time of set- documenting extant taxa, but also as a re- tlement of Indiana, shallow wetlands were so source for palaeoecological inference. Much plentiful that in the spring of the one research on the existing mollusk faunas and could put a canoe in at the area that is now their relationship to vertebrate communities, Fort Wayne and travel all the way to Lake predominating vegetation, wetland hydrology Michigan without having to portage more than and morphometry, substrate type, and water a mile or two. It would seem then, that habitat chemistry is recommended. These data will and food loss are not likely factors in the ex- not only add to our knowledge of extant com- tinction of the giant Beaver. munities, but it will also facilitate inferences The exact reason for the extinction of the about palaeoenvironments and their succes- giant beaver and the other North American sion. Additionally, further research on the sub- "ice age" is not known. However, fossils in the marl deposits of Indiana, and there are two changes that occurred at about elsewhere, would provide more precise doc- the time the megafauna began to go extinct; umentation and understanding of late-Pleisto- climate and the immigration of humans to cene and Holocene biogeography. . The changes associated with The habitat of Castoroides ohioensis. — transitions from interglacial climates to glacial The Wilkinson beaver died near the time when climates, and back again, do not seem to be a its species went extinct, circa 10,000 logical explanation for the extinctions, be- ago (see Cahn 1932). The Wilkinson site at cause such glaciation cycles have occurred the time the specimen died was a mineral-rich, many times during the Quaternary with ap- wet meadow, dominated by bulrushes. Cat- parently no major effect on the populations of tails, although not evidenced by subfossils, the North American megafauna. Therefore, were probably also present in appreciable the only apparent, new variable that occurred numbers. The surrounding forest was domi- during the last glaciation is the appearance of nated by white spruce, balsam fir, and tama- humans. Whether people negatively affected rack, with birch and aspen probably occupy- the megafauna via hunting, introduction of ing disturbed sites and lakeshores. disease, or both, is still a subject of much con- Many authors believe that a reduction or troversy. loss of the preferred habitat of the giant beaver ACKNOWLEDGMENTS at the end of the Pleistocene and perhaps its overspecialization, including the inability to We thank Mr. Luke Hunt, Whitko High disperse readily and to build dams, contrib- School, for bringing the Castoroides remains uted to its extinction (Stirton 1965; Kurten & to our attention. Monte and his father Galen Anderson 1980; Harington 1986; Holman Wilkinson kindly allowed recovery on their 1995). The question of habitat loss can be ad- property, assisted greatly with the operation of dressed by studying palaeoenvironments and a backhoe, and donated all materials to the SWINEHART & RICHARDS—INDIANA PLEISTOCENE GIANT BEAVER 65

Indiana State Museum. We also thank numer- Grimm, E.C. 1996. Tilia/Tilia«Graph. Eric C. ous staff and volunteers of the Indiana State Grimm, Illinois State Museum, Research and Collections Center, 1011 East Ash Street, Spring- Museum for making the difficult recovery in field, Illinois 62703. sub-freezing weather possible. Volunteer Vern Harington, C.R. 1986. The giant beaver. Neotoma Swanson undertook considerable effort to re- 20, 3 p. National Museum of Natural Sciences. wash and sort the biotic concentrate that fa- Harmen, W.N. & CO. Berg. 1971. The freshwater cilitated the present study. snails of central New York. SEARCH-Agricul- LITERATURE CITED ture (Cornell University) 1:1-68. Hay, O.R 1912. The Pleistocene period and its ver- Adams, W.R. 1946. Archaeological survey of Mar- tebrata. Pp. 541-784, In Thirty-sixth Annual Re- tin County, Pp. 197-198, In Indiana History Bul- port, Indiana Department of Geology and Natural letin 23(6). Resources, 1911. Baker, EC. 1918. Post-glacial molluska from the Hay, O.R 1912. The recognition of Pleistocene marls of central Illinois. Journal of Geology 26: faunas. Smithsonian 659-671. Miscellaneous Collections 59(20): 1-16. Baker, EC. 1920. Pleistocene mollusca from Indi- Hay, O.R 1923. The Pleistocene of North America ana and Ohio. Journal of Geology 28:439-457. and its vertebrated animals from the states east Baker, EC. 1930. A new record of Castoroides of the Mississippi River and from the Canadian ohioensis from Illinois. Science 71:389. provinces east of longitude 95 [D]. Carnegie In- Blatchley, W.S. & G. Ashley. 1901. The lakes of stitution of Washington Publication 32:1-532. northern Indiana and their associated marl de- Holman, J. A. 1975. Michigan's fossil vertebrates. posits. Annual Report of the Indiana Department Publications of the Michigan State of Geology and Natural Resources 1900:33-321. Museum, University, Educational Bulletin No. 2. 54 Barbour, E.H. 1931. The giant beaver, Castoroides, pp. Holman, J. A. 1995. Ancient Life of the Great and the common beaver, Castor, in Nebraska. 1- Lakes Basin. The University of Michigan Press, The Nebraska State Museum Bulletin 20( 1 ): 17 186. Ann Arbor. 287 pp. Jackson, S.T D.R. Whitehead, n.d. Prairie Cahn, A.R. 1932. Records and distribution of the & Creek pollen plant macrofossils: fossil beaver, Castoroides ohioensis. Journal of and Paleoecological Mammalogy 13:229-241. inferences. Unpublished manuscript. Department Crum, H.A. & L.E. Anderson. 1981. Mosses of of Biology, Indiana University, Bloomington. 6 Eastern North America. Columbia University pp. Jackson, S.T. D.R. Whitehead. 1986. Late-gla- Press, New York. 2 vol., 1328 pp. & Cummings, K.S. & C.A. Mayer. 1992. A Guide to cial and early Holocene vegetational history at Freshwater Mussels of the Midwest. Manual 5, the Kolarik Site, Northwestern, Indi-

Illinois Natural History Survey, Champaign. 194 ana. American Midland Naturalist 1 15:361-373. pp. Jessen, K. 1955. Key to subfossil Potamogeton. Dexter, R.W. 1950. Distribution of the mollusks in Botanisk Tidsskrift 52:1-7. a basic bog lake and its margins. The Nautilus Kurten, B., and E. Anderson. 1980. Pleistocene 64:19-26. of North America. Columbia Univer- Engels, W.L. 1931. Two new records of the Pleis- sity Press, New York. 442 pp. tocene beaver, Castoroides ohioensis. American La Rocque, A. 1952. Molluscan faunas of the Or- Midland Naturalist 12:529-532. leton Mastodon Site, Madison County, Ohio. Goodrich, C. & H. van der Schalie. 1944. A re- Ohio Journal of Science 52:10-27. vision of the Mollusca of Indiana. American LaRocque, A. & J. Forsythe. 1957. Pleistocene Midland Naturalist 32:257-326. molluscan faunules of the Sidney Cut. Shelby

Graham, R.W., J. A. Hoi man & P.W. Parmalee. County, Ohio. Ohio Journal of Science 57:81- 1983. Taphonomy and paleoecology of the 89. Christensen bog mastodon bone bed, Hancock Martin, A.C. & W.D. Barkley. 1961. Seed Identi- County, Indiana. Illinois State Museum Reports fication Manual. University of California Press.

of Investigations 38. 29 p. 221 pp. Gray, H.H. 1987. Bedrock Geologic Map of Indi- Martin, H.T 1912. On a comparison of three ana. Indiana Department of Natural Resources, skulls, Castoroides ohioensis, Castoroides kan-

Geological Survey, Bloomington, Indiana. Mis- sansus, and Castor. University ol' Kansas Sci- cellaneous Map 48. ence Bulletin. 6:389-396. Gray, H.H. 1989. Quaternary Geologic Map of In- McDonald, H.G. 1994. The late Pleistocene ver- diana. Indiana Department of Natural Resources, tebrate fauna in Ohio: Co-inhabitants with Ohio's

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