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Comparative Evolutionary Palaeoecology: Assessing the Changing Ecology of the Past

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Comparative Evolutionary Palaeoecology: Assessing the Changing Ecology of the Past Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021 Comparative evolutionary palaeoecology: assessing the changing ecology of the past DAVID J. BOTTJER, 1 JENNIFER K. SCHUBERT 2 & MARY L. DROSER 3 1Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, USA 2Department of Geological Sciences, University of Miami, Miami, FL 33124, USA 3Department of Earth Sciences, University of California, Riverside, CJl 92521, USA Abstract: Various palaeoecological trends have been identified in the Phanerozoic, each focusing on different aspects of the fossil record. Patterns that have been described include histories of tiering, palaeocommunity species richness, and guild occupation in evolutionary faunas, as well as onshore-offshore trends in origination, expansion and retreat. Patterns of change through time have also been documented from biosedimentological features (ichnofabrics, microbial structures, shell beds). Such trends can be compared and contrasted to yield unique insights into understanding the changing ecology of the past, and in particular may be helpful in evaluating the relative degree of ecological degradation caused by a mass extinction. This comparative approach can also shed light on a variety of fundamental palaeobiological problems, for example, why no new body plans (phyla) have evolved since the early Phanerozoic. Causes of this phenomenon are thought to be either: (1) ecospace was not sufficiently open after the early Phanerozoic for survival of new body plans; or (2) accumulating developmental constraints after the early Phanerozoic have prevented the evolution of new body plans. Because the Permian-Triassic mass extinction was the most devastating biotic crisis of the Phanerozoic, one might expect new body plans to appear if ecospace were the primary limiting factor and opened sufficiently by this mass extinction. Although previous studies have shown that ecospace availability in the Cambrian and Early Triassic was indeed different, this comparative approach indicates that ecological conditions in the Early Triassic were most like those of the Late Cambrian/Early Ordovician. Thus, if ecospace availability has constrained the survival of new body plans, then ecospace has always been sufficiently filled after the Cambrian explosion to inhibit their evolution. Evolutionary palaeoecology examines the inter- for deciphering the ecological context of mass play of evolution and ecology on a geological extinction aftermaths. time scale through the filter of the fossil and stratigraphic record. Although a variety of Phanerozoic palaeoecological trends approaches has been utilized in previous studies concerning evolutionary palaeoecology, perhaps Palaeoecology originally developed as a metho- the most significant achievement of this research dology for palaeoenvironmental reconstruction has been the recognition of long-term palaeo- (e.g. Bottjer et al. 1995). Widespread application ecological trends over 10 6 to 10 9 years. Such of ecological approaches in palaeontological trends include changes in Phanerozoic benthic data collection through the 1960s and 1970s marine palaeocommunity species richness, tier- (e.g. Valentine 1973) led to the development of a ing and evolutionary fauna guild occupation as suitably large database to facilitate syntheses of well as onshore--offshore patterns and changes long-term ecological trends through some or all through time of biosedimentological features of the Phanerozoic. Perhaps the earliest Phaner- (ichnofabrics, microbial structures, shell beds). ozoic trend to be documented was that of These trends can be compared and contrasted palaeocommunity species richness (Bambach among themselves and with other biotic trends 1977). Application of ecological approaches (such as Phanerozoic familial diversity, e.g. towards an understanding of the Precambrian Sepkoski 1992) to yield unique insight in under- fossil records has also been fruitful, with perhaps standing the changing ecology of the past. In the most convincing Precambrian palaeoecolo- particular, comparative evolutionary palaeo- gical trend being that of long-term stromatolite ecology can be an especially effective approach decline, which began in the late Proterozoic (e.g. From Hart, M. B. (ed.), 1996, Biotic Recoveryfrom Mass Extinction Events, Geological Society Special Publication No. 102, pp. 1-13 Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021 2 D.J. BOTTJER ET AL. (a) (b) CAMBRIAN FAUNA MEDIAN HIGH VARIABLE OPEN NUMBER STRESS NEARSHORE MARINE OF SPECIES ENVIRONMENTS ENVIRONMENTS ENVIRONMENTS PELAGIC CENOZOIC $.S 39 61.5 SUSPENSION HERBIVORE CARNIVORE MESOZOIC 7.5 17 2 S f UPPER II 16 30 PALEOZOIC EPIFAUNA MIDDLE 9.5 19.5 30.S SUSPENSION DEPOSIT HERBIVORE PALEOZOIC LOWER 7 12.11 19 w BBmm PALEOZOIC (e) ATTACHED I ERECT MIDDLE AND UPPER PALEOZOIC FAUNA RECLINING PELAGIC INFAUNA SUSPENSION HERBIVORE CARNIVORE SUSPENSION DEPOEIT CARNIVORE ], I I 4J SHALLOW PASSIVE EPIFAUNA SHALLOW 1 2 1 ACT1VE SUSPENBION OEPOSIT HERBIVORE CARNIVORE DEEP MOBILE I 4 5 5 PASSIVE ATTACHED 7 DEEP LOW ACTIVE I AI"rACHEI: 7 ERECT (d) RECUmNa 5 MESOZOIC - CENOZOIC FAUNA INFAUNA PELAGIC SUSPENSION HERBIVORE CARNIVORE SUBPENBION DEPOEIT SHALLOW ; 2 PASS~ I , I . SHALLOW 2 4 2 EPIFAUNA DEEP SUSPENSION DEPOSIT HERBIVORE CARNIVORE DEEP MOBILE 2 2 5 DEEP ACTIVE 1 I ATTACHED 7 LOW ArrACHED 6 Fig. 1. Trends in Phanerozoic benthic marine palaeo- ERECT community species richness and evolutionary fauna guild occupation. (a) Median number of species in RECLINING 4 palaeocommunities for various Phanerozoic times and environments, modified from Bambach (1977). Ca) INFAUNA General adaptive strategies that typify the more SUSPENIION DEPOEIT CARNIVORE diverse classes of the Cambrian evolutionary fauna. SHALLOW 3 1 1 (¢) General adaptive strategies that typify the more diverse classes of the Palaeozoic evolutionary fauna. SHALLOW 3 4 3 ACT1VE (d) General adaptive strategies that typify the more ¢.~,.:.-., ::~;....;:,:::.:,.... :...:..::: • ..-:...:::::;:-. diverse classes of the Mesozoic-Cenozoic (Modem) DEEP ':..:-v~~..:i';:::..',:.:"., 'J :.:,;:'!. :.:':-~:~.:-::."::." ";'::: evolutionary fauna. For b, c, d the number of more PASSIVE ]~.-,Y.?-:Z--"..':."":'.;.'.';:i:'.':.'::: ".." :;";-." '.': diverse classes which show each adaptive strategy is DEEP 2 1 indicated in the boxes, with empty boxes indicating no ACTIVE classes present at that time and stippled boxes indicating not biologically practical adaptive strate- gies; modified from Bambach (1983), identity of summed classes can be found in Bambach (1983). Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021 COMPARATIVE EVOLUTIONARY PALAEOECOLOGY 3 Garrett 1970; Awramik 1971, 1990, 1991; Walter exploitation of more ecospace than was typical & Heys 1985). To illustrate the variety of ways in of the preceding fauna. which palaeoecological trends are documented, several examples are described below. A detailed Tiering summation of some of these as well as a variety of other palaeoecological trends can be found in Ausich & Bottjer (1982) defined tiering as the Bambach (1986), Vermeij (1987) and Sepkoski et distribution of benthic organisms within the al. (1991). space above and below the seafloor. In ecologi- cal studies the term 'stratification' is used, but Palaeocommunity species richness because this term has other meanings in geology, tiering has received widespread acceptance in Bambach (1977) synthesized data on species analyses of palaeocommunities (e.g. Watkins richness from 366 Phanerozoic palaeocommu- 1991) as well as trace fossils (e.g. Droser & nities occurring in a variety of level-bottom Bottjer 1993). Ausich & Bottjer (1982) proposed marine benthic palaeoenvironments. From this a Phanerozoic history for tiering of suspension he determined the median number of species/ feeders in level-bottom settings of one broad palaeocommunity for five Phanerozoic time palaeoenvironment, that of shallow subtidal intervals. Throughout the Phanerozoic the med- shelves and epicontinental seas. This history ian number of species always increases from has been modified in subsequent publications as marginal marine high stress environments to additional data on tiering have accumulated offshore open marine environments (Fig. l a). (Bottjer & Ausich 1986; Ausich & Bottjer 1991) Both variable nearshore and open marine (Fig. 2a). From this analysis a four-phase tiering environments show an increase in the median history can be recognized. The initial phase, number of species from the lower to the middle during the Cambrian, had very low levels of Palaeozoic, but these values then stay relatively both infaunal and epifaunal tiering (Fig. 2a). the same until the Cenozoic, when the median Phase two, from the Ordovician through the number of species/palaeocommunity for each of Permian, is characterized by complex epifaunal these environments more than doubles corre- tiering as well as, towards the end of the sponding Mesozoic values (Fig. 1a). The median Palaeozoic, increases in infaunal tiering (Fig. number of species/palaeocommunity stays about 2a). The mid-Triassic through Jurassic constitu- the same throughout the Phanerozoic in high tes phase three, and was a time where the stress marginal marine environments (Fig. l a). potential existed for maximum infaunal and This analysis was the first to show that within- epifaunal tiering (Fig. 2a). Phase four (Creta- habitat species richness has increased through ceous
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