Figure 1.
PaleoDB collections from the Cretaceous 6 bin.
The three regions examined: European Epicontinental Sea (orange), North American Cretaceous Seaway (yellow), and Gulf Coast (red). Map: Ron Blakey, NAU Geology [21].
Figure 2.
Spatial protocol used in this study to build genus-area curves from fossil data.
Blue dots represent fossil collections in the PaleoDB of marine invertebrates during the Cretaceous 6 time bin from the European Epicontinental sea. Inset: One collection was randomly chosen as a start point (yellow star); a convex hull was circumscribed around the start collection and the next two closest collections. Main figure: Each collection was added individually and a new convex hull was circumscribed around collections in order to calculate area. The rainbow lines represent a few convex hulls from this iteration. This process was then repeated using each collection as a start point.
Figure 3.
Example of multiple genus-area relationship
(GAR) analyses plotted together. Gray dots represent all iterations regionally; black dots represent the single iteration illustrated in Fig. 2. The colored dots correspond to the hulls pictured in Fig. 2. Data are from the European Epicontinental Sea during the Cretaceous 6 time bin.
Figure 4.
Changes to the genus-area relationship best-fit line due to changes in alpha and beta diversity.
(A) Alpha-diversity is higher in the blue region; beta-diversity is identical. (B) Alpha-diversity is identical in the two regions; beta-diversity is higher in the blue region. (C) Both alpha and beta-diversity are higher in the blue region.
Figure 5.
Genus-area (GAR) plots of the European Epicontinental Sea, the North American Cretaceous Interior Seaway and the Gulf Coast, an open-ocean-facing setting. Cretaceous 5–8 represent four ∼11 million year time bins spanning the Late Cretaceous (see text for discussion of time scale). Ordinary least-squares (black) and generalized least-squares (gray) linear regressions are also plotted. All slopes are highly significant, and each is significantly different from all others. Note: when it appears that only one regression line is present this is because the two lines coincide.
Table 1.
P-values for tests of significant differences between individual genus-area linear regression slopes.
Table 2.
Slope and intercept estimates for ordinary least squares (OLS) and generalized least-squares (GLS) linear regression.
Figure 6.
European Epicontinental Sea PaleoDB Collections.
(A) Paleogeographic map of Europe (105Ma). Gray dots represent all PaleoDB collections from the European Epicontinental Sea used in full analyses; red dots represent collections used as a subset for the European Epicontinental Sea analysis. Map: Ron Blakey, NAU Geology [21]. (B) Genus-Area plots with least-squares linear regression of subseted European Data.
Figure 7.
A comparison between least squares linear regression and LOESS regression.
Least squares linear regression is displayed with dashed lines; LOESS by solid lines for (A) the European Epicontiental sea, (B) the North American Cretaceous interior seaway, and (C) the Gulf coast. LOESS was conducted with an alpha (smoothing parameter) of 0.4.
Figure 8.
Shown here are the European Epicontinental Sea, the North American Cretaceous Interior Seaway and the Gulf Coast for the Cretaceous 6 time bin, which includes stages: Turonian, Coniacian and Santonian. Time bins Cretaceous 5, 7 and 8 each span only 1 stage: Cenomanian, Campanian and Maastrichtian respectively.
Figure 9.
Range of least-squares linear regression slopes for each region.
Black dots represent actual slope values, while the colored lines represent the range in values for a given region. Solid lines represent values for analyses using PaleoDB temporal bins (Cretaceous 5–8); dotted lines represent slope values using stage divisions. White dots represent the stages within the Cretaceous 6 PaleoDB time bin: Turonian (T), Coniacian (C) and Santonian (S).