. Bulletins of American paleontology. Hydrology, Vegetation, and Climate: Winkler et al. 89 A06 A23 Sponge spicule pieces per g dry wt Sponge spicule pieces per g dry wt a V Q 0-7- 1 1 1 1 1 1 7-14- h1>+â 14-20- ~~^]IZi:::=«>-i 20-25 - >-(â 25-32 - 32-39 - 39-45 - JII^;&o-i 45-50- ^0<^^ 50-57- I960 *l- 30 YBP - 64-70-( 70-75 -< 2100 -^/- 30 YBP a. o. 1380 +/- 70 YBP 1660 -fZ-lOO YBP 1890 +/- 70 YBP 2600 *l- 70 YBP 2840 +/- 70 ^ BP 2830 â ^/- 60 YBP 2840 +/- 70 YBP a. b. Text-Hgure sample. -Sponge spicule pieces per gram dry weight for A06 and A23. Erro
. Bulletins of American paleontology. Hydrology, Vegetation, and Climate: Winkler et al. 89 A06 A23 Sponge spicule pieces per g dry wt Sponge spicule pieces per g dry wt a V Q 0-7- 1 1 1 1 1 1 7-14- h1>+â 14-20- ~~^]IZi:::=«>-i 20-25 - >-(â 25-32 - 32-39 - 39-45 - JII^;&o-i 45-50- ^0<^^ 50-57- I960 *l- 30 YBP - 64-70-( 70-75 -< 2100 -^/- 30 YBP a. o. 1380 +/- 70 YBP 1660 -fZ-lOO YBP 1890 +/- 70 YBP 2600 *l- 70 YBP 2840 +/- 70 ^ BP 2830 â ^/- 60 YBP 2840 +/- 70 YBP a. b. Text-Hgure sample. -Sponge spicule pieces per gram dry weight for A06 and A23. Error bars = 1 standard deviation based on 4 replicates per complete spicules from 20-14 cm depth indicates that megascleres average at least 396 |xm long (range 300- 476 [Jim, 43 |xm) by 30 jjim w (range, |jLm, |jLm). Several taxa have smooth mega- scleres in this size range: Ephydatia fluviatilis, Spon- gillci alba, and S. cenota (Frost 1991). Unfortunately, identification is based on microscleres and gem- moscleres, which are scarce in A06 deposits. The few gemmoscleres seen resemble those of Spongilla laciis- tris. but the spines are not very well defined. These spicules are slightly bent cylindrical fusiform am- phioxes from 60-70 ixm 1 with sparsely, but ± uni- formly distributed, short, broad-based spines (Plate 1, fig. 4). With light microscopy the axial canal is visible running lengthwise within this spicule type. The ab- sence of definite inicroscleres and the large size of the megascleres suggest that E. fluviatilis may also be pre- sent, but its birotulate gemmoscleres were not seen. Sponge spicule pieces are present in every sampling increment of the A06 core, but they are rare in the dark organic marl (75-57 cm. Text-fig. 17a). Two peaks in sponge spicule pieces are, however, apparent in the peat: one at 45-39 cm and another at 20-14 cm. when diatom frustules are also most numerous. A23H Sponge spicules were found throughout the A23 de- p
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