Accepted Manuscript

End-Triassic nonmarine biotic events

Spencer G. Lucas, Lawrence H. Tanner

PII: S2095-3836(15)00021-8 DOI: 10.1016/j.jop.2015.08.010 Reference: JOP 13

To appear in: Journal of Palaeogeography

Received Date: 1 July 2015

Accepted Date: 15 August 2015

Please cite this article as: Lucas, S.G., Tanner, L.H., End-Triassic nonmarine biotic events, Journal of Palaeogeography (2015), doi: 10.1016/j.jop.2015.08.010.

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Journal of Palaeogeography, (2015), 4, (4), 000−000 DOI:

1Biopalaeogeography and palaeoecology End-Triassic nonmarine biotic events

Spencer G. Lucasa,*, Lawrence H. Tannerb

a New Mexico Museum of Natural History, 1801 Mountain Road NW, Albuquerque, New Mexico 87104- 1375 USA b Department of Biological Sciences, Le Moyne College, 1418 Salt Springs Road, Syracuse, NY 13214 USA

Received 1 July 2015; accepted 18 August 2015 Available online

Abstract The Late Triassic was a prolonged interval of elevated extinction rates and low origination rates that manifestedMANUSCRIPT themselves in a series of extinctions during Carnian, Norian and Rhaetian time. Most of these extinctions took place in the marine realm, particularly affecting radiolarians, conodonts, bivalves, ammonoids and reef-building organisms. On land, the case for a Late

Triassic mass extinction is much more tenuous and has largely focused on tetrapod vertebrates (amphibians and reptiles), though some workers advocate a sudden end-Triassic (TJB) extinction of land plants. Nevertheless, an extensive literature does not identify a major extinction of land plants at the TJB, and a comprehensiveACCEPTED review of palynological records concluded that TJB vegetation

* Corresponding author. E-mail address: [email protected]. Peer review under responsibility of China University of Petroleum (Beijing).

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changes were non-uniform (different changes in different places), not synchronous and not indicative of a mass extinction of land plants. Claims of a substantial perturbation of plant ecology and diversity at the TJB in East

Greenland are indicative of a local change in the paleoflora largely driven by lithofacies changes resulting in changing taphonomic filters. Plant extinctions at the TJB were palaeogeographically localized events, not global in extent. With new and more detailed stratigraphic data, the perceived TJB tetrapod extinction is mostly an artifact of coarse temporal resolution, the compiled correlation effect.

The amphibian, archosaur and synapsid extinctions of the Late Triassic are not concentrated at the TJB, but instead occur stepwise, beginning in the Norian and extending into the Hettangian. There was a disruption of the terrestrial ecosystem across the TJB, but it was more modest than generally claimed. The ecological severity of the end-Triassic nonmarine biotic MANUSCRIPT events are relatively low on the global scale. Biotic turnover at the end of the Triassic was likely driven by the

CAMP eruptions, which caused significant environmental perturbations (cooling, warming, acidification) through outgassing, but the effects on the nonmarine biota appear to have been localized, transient and not catastrophic. Long-term changes in the terrestrial biota across the TJB are complex, diachronous and likely climate driven evolutionary changes in the context of fluctuating background extinction rates, not a single, sudden or mass extinction.

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KEYWORDS Triassic-Jurassic boundary, mass extinction, land plants, East

Greenland, tetrapods, Newark Supergroup, CAMP volcanism

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1 Introduction

The biodiversity crisis at the end of the Triassic (Triassic-Jurassic boundary:

TJB) has long been identified as one of the “big five” mass extinctions of the

Phanerozoic (Sepkoski, 1982). However, during the last decade, we have questioned this identification of a severe and sudden biotic decline at the TJB (Hallam, 2002; Lucas and

Tanner, 2004, 2008; also see Tanner et al., 2004). Instead, our thesis is that the Late

Triassic was a prolonged (approximately 30-million-year-long) interval of elevated extinction rates and low origination rates that manifested themselves in a series of discrete extinctions during Carnian, Norian and Rhaetian time. Most of these extinctions took place in the marine realm, particularly affecting radiolarians, conodonts, bivalves, ammonoids and reef-building organisms (Lucas and Tanner, 2008). On land, the case for a Late Triassic mass extinction is much more tenuous and has largely focused on tetrapod vertebrates (amphibians and reptiles), though some MANUSCRIPT workers advocate a sudden end- Triassic extinction of land plants as well. Here, we focus on the Late Triassic record of land plants and terrestrial tetrapods to demonstrate that they do not document a sudden or a severe end-Triassic extinction. From a palaeogeographical point of view, the nonmarine fossil record identifies some local extinctions across the TJB, but no global mass extinction.

2 Late TriassicACCEPTED−Early Jurassic timescale We use the standard global chronostratigraphic timescale for the Late Triassic- Early Jurassic compiled by Ogg (2012a, 2012b), but modified with regard to some recent data and analyses of its radioisotopic calibration (Lucas et al., 2012; Ogg et al., 2014; Wotzlaw et al., 2014) (Figure 1). The base of one of the three Late Triassic stages

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(Carnian) has an agreed on GSSP (global stratotype section and point), and the base of the Norian stage will be defined by a conodont datum that is close to the traditional ammonoid-based boundary (Balini et al. 2010; Krystyn et al. 2007; Lucas, 2010a, 2013b; Orchard, 2010, 2013, 2014). The favored definition of the Rhaetian base has as its primary signal the LO (lowest occurrence) of the conodont Misikella posthernsteini. At present, the only fully published GSSP candidate for the Rhaetian base is the Steinbergkogel section near Hallstatt, Austria (Krystyn et al., 2007). However, Giordano et al. (2010) concluded that the LO of Misikella posthernsteini is actually younger at Steinbergkogel than it is in the section they studied in the Lagronegro basin in southern Italy, so the Italian section may become the GSSP location. The GSSP defined for the TJB (base of Jurassic System = base of Hettangian Stage) is correlated by the lowest occurrence of the ammonoid Psiloceras spelae (Hillebrandt et al., 2013). The best numerical calibration places this boundary close to 201.4 Ma (Schoene et al., 2010; Figure 1).

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Figure 1 Correlation of the Late Triassic−earliest Jurassic standard global chronostratigraphic scale

(sgcs) to tetrapod biochronology based on land-vertebrate faunachrons (lvfs). See text for sources.

Correlation of nonmarine and marine biochronology in the Late Triassic−Early Jurassic remains imprecise. Here, we primarily rely on the correlations based on tetrapod biostratigraphyACCEPTED and biochronology (land-vertebrate faunachrons) advocated by Lucas (1998, 2008, 2010b), Lucas et al. (2007a, 2012) and Lucas and Tanner (2007b) (Figure 1). Many Late Triassic megafossil plant localities can be directly related to this tetrapod- based biochronology (e.g., Lucas, 2013a). Palynostratigraphic correlations in much of this interval are discussed in a comprehensive way by Cirilli (2010) and Kürschner and

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Herngreen (2010). Conchostracan biostratigraphy for the Late Triassic−Early Jurassic also can be tied directly to the tetrapod biostratigraphy and biochronology (Kozur and Weems, 2005, 2007, 2010; Lucas et al., 2011, 2012; Weems and Lucas, 2015). An extremely important point is that correlation of Late Triassic nonmarine biochronology to the standard global chronostratigraphic scale is achieved primarily by correlation to the Germanic basin section, where marine intercalations and other data provide a reasonably precise cross correlation to the marine Upper Triassic sections in Austria and Italy (Kozur and Bachman, 2005, 2008; Kozur and Weems, 2010; Lucas, 2010a, 2010b). For the Lower Jurassic, nonmarine-marine correlation tiepoints exist (e. g., Lucas, 2008), but are constrained in much less detail than is the Upper Triassic record. Magnetostratigraphy also provides some service to correlation of nonmarine and marine strata across the TJB, but not the precision always needed. The Rhaetian-early Hettangian interval is a time of dominantly normal polarity, and each section studied reveals from two to four short intervals of reversed polarity in the dominantly normal Rhaetian-Hettangian multichron (e.g., Hounslow and Muttoni, 2010; Hounslow et al., 2004; Lucas and Tanner, 2007b; Lucas et al., 2011; Marzoli et al., 2004). Correlation of these short reversals to each other is not straightforwardMANUSCRIPT and forces a reliance on biostratigraphic or chemostratigraphic inferences to provide precise correlations within the Rhaetian-Hettangian multichron (for example, see Lucas and Tanner, 2007b, Figure 7). Incorrect placement of the TJB boundary in the Newark Supergroup long confounded nonmarine-marine correlations and gave the impression of a significant extinction of plants and tetrapods at the TJB (see discussion below). However, well supported and now well accepted correlation of the TJB in the Newark section (Cirilli et al., 2009; Kozur and Weems, 2005, 2007, 2010; Lucas and Tanner, 2007b; Olsen et al., 2011, 2015; Whiteside et al., 2010) moves the boundary upward stratigraphically to a level well removedACCEPTED from any evidence of a sudden biotic turnover. Correlation of nonmarine strata to the now defined TJB in marine strata is achieved by some workers using either palynostratigraphy or carbon isotope stratigraphy. However, palynostratigraphy does not unambiguously identify the boundary in many sections (Bonis and Kürschner, 2012; Bonis et al., 2009; Pieńkowski et al., 2011). And,

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many nonmarine carbon isotope records rely on too few data points to convincingly identify the carbon-isotope excursions recognized in marine sections across the TJB or produce records with such high noise levels as to defy correlation (e.g., McEwain et al., 1999). Recent examples of such problematic carbon-isotope-based correlations of the TJB in nonmarine strata include Gómez et al. (2007) in Spain, Whiteside et al. (2010) in the USA, Pieńkowski et al. (2011, 2014) in Poland and Hesselbo et al.’s (2002) carbon- isotope curve in East Greenland, discussed below. Nevertheless, such considerations do not deter some workers from precise placement of the TJB in nonmarine sections where few if any data exist to support precise placement. Thus, for example, Sha et al. (2011, 2015) recently placed the TJB in nonmarine strata of the Junggur Basin in northwestern China using palynomorphs and nonmarine bivalves that cannot be unambiguously correlated with precision to any other TJB section. More problematic are nonmarine sections where the TJB can only be approximated, and that approximation separates very different nonmarine fossil assemblages that differ in age by many millions of years. A good example of this is provided by the study of the tetrapod record MANUSCRIPT in the Gondwana basins of India by Bandyopadhyay and Sengupta (2006). This record has an obviously Late Triassic tetrapod assemblage (with phytosaurs, aetosaurs, etc) of likely Norian age in the lower Dharmaram Formation, overlain hundreds of meters higher by the clearly Jurassic (likely Sinemurian), dinosaur-dominated tetrapod assemblage of the Kota Formation. All that intervenes are two undescribed tetrapod taxa—a sphenodontian and a plateosaurid dinosaur—from the upper Dharmaram Formation. Lucas and Huber (2003) suggested these fossils are likely Late Triassic in age, but Bandyopadhyay and Sengupta (2006) assigned them a Hettangian age. They then claimed the Gondwana basin record shows a substantial turnover in tetrapods at the TJB, even though the two assemblages in India that are comparableACCEPTED across that boundary are likely Norian and Sinemurian in age, and thus separated by at least 6 million years, invalidating their conclusion. Another example comes from the work of Pieńkowski et al. (2011, 2014) in Poland, where late Norian tetrapod body fossils are compared to Hettangian? footprint assemblages and show a change from diverse, dicynodont- and archosaur-dominated

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faunas to dinosaur-dominated footprint faunas. Dinosaur-dominated footprint faunas, however, are also known from the Late Triassic (e.g., Lucas, 2007), so the comparison of the Polish Norian bone and Hettangian? footprint records does not necessarily reflect biotic turnover across the TJB.

3 TJB terrestrial record

It is fair to say that only seven places on Earth have a record of non-marine TJB fossil plants and tetrapods of sufficient extent, diversity and stratigraphic density to be relevant to evaluating a TJB extinction: (1) Chinle-Glen Canyon Group succession of the American Southwest; (2) Newark Supergroup strata of the eastern seaboard of North America from Nova Scotia to the Carolinas, and including rift basin deposits of Morocco in North Africa; (3) Jameson Land in eastern Greenland; (4) European records inside and outside of the Germanic basin, particularly in Germany, the United Kingdom and Italy; (6) northwestern Argentina; and (7) the Karoo basin of South Africa (Figure 2). MANUSCRIPT

Figure 2 PrincipalACCEPTED localities that are referred to in the text where the nonmarine Triassic−Jurassic boundary interval has a dense fossil record: A = Argentina, C= Chinle basin, American Southwest, G = Germanic basin, J = Jameson Land, East Greenland and N = Newark Supergroup basins.

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Today, and (based on actualism) during the TJB interval, much terrestrial diversity is accounted for by monerans and arthropods. Yet, the monerans have virtually no fossil record, and the record of arthropods across the TJB is essentially nonexistent for many groups. Arthropod groups that have relatively good TJB fossil records, such as ostracods and conchostracans, show no significant extinction at the TJB (e.g., Kozur and Weems, 2010). Insects also have a fossil record that shows no evidence of a diversity crash across the TJB (Grimaldi and Engel, 2005; Labandeira and Sepkoski, 1993). Indeed, Grimaldi and Engel (2005, p. 73) concluded, “there seems to have been little differentiation between insect faunas of the Late Triassic and Early Jurassic.” Plant diversity across the TJB is based on a much better fossil record, both in the form of megafossil plants and their microfossil “proxies,” the palynomorphs (sporomorphs). The record of terrestrial fossil vertebrates across the TJB is comparable in quality to the plant record, and it shows no evident extinction of freshwater fishes (McCune and Schaeffer, 1986; Milner et al., 2006). Supposed TJB tetrapod extinctions focus on three principal groups: temnospondyl amphibians, some archosaur taxa and some synapsid taxa. These records have been evaluated using both body fossils (bones and teeth) and trace fossils (footprints). MANUSCRIPT

4 Land plants

4.1 Overview

An extensive literature does not identify a major extinction of land plants at the TJB (e.g., Ash, 1986; Brugman, 1983; Burgoyne et al., 2005; Cascales-Miñana and Cleal, 2012; Cleal, 1993a, 1993b; Edwards, 1993; Fisher and Dunay, 1981; Galli et al., 2005; Hallam, 2002; Kelber, 1998; Knoll, 1984; Kuerschner et al., 2007; Lucas and Tanner, 2004, 2007b, 2008; McElwain and Punyasena, 2007; Niklas et al., 1983; Orbell, 1973; Pedersen and Lund, 1980; Ruckwied et al., 2008; Schuurman, 1979; Tanner et al., 2004; Traverse, 1988).ACCEPTED Most reviews identify only the extinction of peltasperms, a clade of seed ferns, at the TJB. Global compilations at the species and family levels show no substantial plant extinction at the TJB (Cleal, 1993a, 1993b; Edwards, 1993; Knoll, 1984; Niklas et al., 1983). A recent analysis by Cascales-Miñana and Cleal (2012: 76-77)

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concluded that “the changes observed in the plant fossil record in the Late Triassic Series are mainly reflecting an ecological reorganization of the terrestrial habitats weeding-out some of the families of less adaptable plants that had filled the newly available niches during Triassic times, rather than a global ecological crisis on the scale of that seen at the end of Permian times.”

Some data do reveal local turnover of paleofloras across the TJB. A good example is a study of Swedish benettitaleans that documented restriction of two species to the Rhaetian followed by five species restricted to the Hettangian. However, this is not considered by its authors, Pott and McLoughlin (2009: 117), as anything more than a “moderate taxonomic turnover,” and it is a palaeogeographically local event.

Contrary to prevailing thought, McElwain and collaborators (Bacon et al., 2013; Belcher et al., 2010; Mander et al., 2010, 2012; McElwain and Punyasena, 2007; McElwain et al., 1999, 2007, 2009) claim significant changes in the megaflora at the TJB in East Greenland (Figure 3). According to these workers, these encompass a sudden change from high diversity Late Triassic plant communities to lower diversity and less taxonomically even Early Jurassic communities.MANUSCRIPT This is the only location where a case has been made for a major turnover in the megaflora at the TJB, but we question whether the data support recognition of a megafloral crisis in East Greenland of more than local palaeogeographic significance.

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Figure 3 Measured secion of Triassic-Jurassic boundary interval of Kap Stewart Group in East Greenland showing distribution of megafossil plants and published carbon-isotope curve. The lithologic column is modified from McElwain et al. (2007) and shows megafossil plant beds using their scheme (1, 1.5, 2, etc.) followed by the scheme used by Harris (1937) in parentheses (Equisetites, A, B, etc.). The carbon isotope curve is from Hesselbo et al. (2002).

4.2 Plant extinctions in east Greenland

The Astartekløft section of the Primulaev Formation of the Kap Stewart Group in Jameson Land, East Greenland (Figure 3) apparently encompasses the TJB and records the transition from the Lepidopteris floral zone to the Thaumatopteris floral zone, with few species shared by both zones (Harris, 1937). The former is characterized by the presence of palynomorphs, including Rhaetipollis, while the latter contains Heliosporites (Pedersen and Lund, 1980), and although extinction of some species across the transition between the two zones is evident, many species occur in both zones. Thus, Harris (1937: 76) emphasized that “real mixing” of the two floral zones occurs over a 10 m interval (Figure 3), and “this is real mixing….the two sets of plants will be seen on the same bedding plane and they continue to be found together from top to bottom, of one of these beds….” Therefore, the data and analyses of HarrisMANUSCRIPT (1937) and Pedersen and Lund (1980) did not identify an abrupt change in the land plants across the TJB in Jameson Land. Furthermore, what species turnover looks abrupt in this section was attributed by Harris (1937) and Pedersen and Lund (1980) to species range truncations at a depositional hiatus, an unconformity also recognized in the Astartekløft section by Dam and Surlyk (1993) and Hesselbo et al. (2002) (Figure 3).

In contrast, in this section McElwain and collaborators claim: (1) a sudden, 85% drop in species diversity at the TJB (based on megafossil plants but not reflected in the palynomorph record); (2) a decrease in the relative abundance of common plant species at the TJB; (3) a change in leaf physiognomy to larger and rounder leaves; (4) an increase in charcoal indicativeACCEPTED of wildfire at the TJB; and (5) an increase in chemical damage to sporomorphs at the TJB. They see all but possibly the last of these as indicative of a “super greenhouse” caused by CAMP eruptions.

We question, though, the validity of the placement of the TJB in the Astartekløft section. McElwain and collaborators place it at about the 47 m level of this section,

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basing that placement on the carbon isotope record published by Hesselbo et al. (2002) o (Figure 3). This record shows an apparent, but modest (~2 /oo), negative excursion beginning at about the 45 m level. We note that this “excursion” coincides with an unconformity of unknown duration. Hence, the relationship of the isotopic trend above this hiatus to the missing, underlying strata is undetermined. Moreover, the general isotopic trend for this section bears little similarity to the published isotope stratigraphy for sections of putative identical age.

Nevertheless, Hesselbo et al. (2002) assumed that the base of the excursion represents the “initial isotope excursion” and that the remainder records the “main isotope excursion” seen in marine sections that cross the TJB (e.g., Ruhl et al., 2010). Therefore, the intervening section with a more positive isotopic trend (spanning 4 m at St. Audrie’s Bay in England) is conveniently missing, so we regard Hesselbo et al.’s (2002) correlation as tenuous at best. Furthermore, if the initial negative excursion at the ~ 45 m level in the Astartekløft section is the well documented (in marine sections) negative excursion in carbon then it is not the TJB, but instead a point in the Rhaetian (e.g., Hillebrandt et al., 2013; Lucas et al., 2007b; Mander et al., 2013; Ruhl et al., 2010;). Thus, all the events McElwain and collaborators MANUSCRIPT associate with the TJB actually preceded it.

The chemostratigraphic correlation proposed by Hesselbo et al. (2002) relies on the presence of an unconformity at 47 m in the Astartekløft section. Questions should be raised about the nature of this unconformity and the temporal magnitude of the hiatus it represents, as well as the associated substantial change in lithofacies (Figure 3). Indeed, we note that most of the megafossil plant assemblages below that level are from mudrock-dominated intervals, whereas almost all of those above that level are from sandstone (Figure 3). According to McElwain et al. (2007, p. 551), the mudrock likely represents floodplain deposits of mainly autochthonous plants, whereas the sandstones represent channelACCEPTED and splay deposits that also include allochthonous plants. However, in evident contradiction to parts of their text and measured stratigraphic section, McElwain et al. (2007, table 1) identify all the plant localities up through their bed 5 as coming from “sheet splay” deposits, the plants from bed 6 as from a coal swamp (though no coal is present in the section at Astartekløft) and their plant beds 7 and 8 as coming from

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abandoned channels. In the absence of more data (e.g., detailed lithologic descriptions of the plant-bearing strata) and an actual sedimentological analysis of the plant-bearing beds, we are not able to resolve these evident contradictions in McElwain et al. (2007).

Instead, it seems evident that the section at Astartekløft embodies a major lithofacies change at an unconformity, from a mudstone- and sheet-sandstone-dominated depositional system to a thick, channel-sandstone dominated system (Figure 3). On face value, it preserves two taphofloras in different lithofacies, and this raises the possibility that at least some of the apparent floral change inferred by McElwain and collaborators is due to the change in the depositional system (lithofacies). Assuming the TJB is present in this section near the 47 m level, the megafossil plant assemblages across the TJB are clearly not “isotaphonomic” (as claimed by McElwain et al., 2007), so they are not strictly comparable to each other in terms of composition, diversity and relative abundance.

According to McElwain and collaborators, a substantial perturbation of plant ecology and diversity is preserved at the TJB in East Greenland. We suggest that the data they present are indicative of a palaeogeographicallyMANUSCRIPT local change in the paleoflora largely driven by lithofacies changes resulting in changing taphonomic filters. No catastrophic land plant extinction is documented and, at most, the floral turnover in East Greenland is nothing more than a palaeogeographically local event, as no similar, coeval event is documented elsewhere (Hallam and Wignall, 1997; Lucas and Tanner, 2008; Tanner et al., 2004;). Furthermore, whatever happened to the megaflora in East Greenland, it happened very late in the Triassic, not at the TJB.

4.3 Plant microfossils

Like the megafossil plant record, the palynological record provides no evidence for a mass extinction of land plants at the TJB (Bonis and Kürschner, 2012). Decades ago, Fisher ACCEPTED and Dunay (1981) demonstrated that a significant proportion of the Rhaetipollis germanicus assemblage that defines the Rhaetian in Europe (e. g., Orbell, 1973; Schuurman, 1979) persists in lowermost Jurassic strata, and this remains the case (e.g., Bonis and Kürschner, 2012; Bonis et al., 2009; Cirilli, 2010; Kürschner and Herngreen, 2010). Brugman (1983) and Traverse (1988) thus concluded that floral

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turnover across the TJB was gradual, not abrupt. Kelber (1998) described the megaflora and palynoflora for Central Europe in a single unit he termed “Rhaeto-Liassic,” and concluded there was no serious disruption or decline in plant diversity across the TJB. More recently, Kuerschner et al. (2007) and Bonis et al. (2009) documented the transitional nature of the change in palynomorphs across the TJB in the Northern Calcareous Alps of Austria (also see Hillebrandt et al., 2013), and the palynomorph record in East Greenland also does not document an abrupt TJB extinction (Mander et al., 2010, 2013). Nevertheless, profound palynomorph extinction at the TJB was long identified in the Newark Supergroup record in eastern North America by Olsen and collaborators (Cornet, 1977; Cornet and Olsen, 1985; Fowell and Olsen, 1993; Olsen and Sues, 1986; Olsen et al., 1990, 2002a, 2002b). Their work identified the TJB in the Newark section by a decrease in diversity of the plant microfossil assemblage, defined by the loss of palynomorphs considered typical of the Late Triassic, followed by dominance of the palynoflora by several species of the genus “Corollina” (= Classopollis), especially C. meyeriana (Cornet and Olsen, 1985; Fowell and Olsen, 1993; Fowell and Traverse, 1995; Fowell et al., 1994; Olsen et al., 1990). They thusMANUSCRIPT placed the TJB in the Newark section at the base of the Classopollis meyeriana palynofloral zone (Figure 4). These workers attached considerable importance to a peak abundance of trilete spores at this level, which they termed a “fern spike” (Cornet and Olsen, 1985; Fowell and Olsen, 1993; Fowell et al., 1994; Whiteside et al., 2007). Although not present in all of the Newark basins (e.g., Cirilli et al., 2009), an increase in trilete spores has been noted in some European sections, where the acme zone is referred to as the Triletes Beds (Kuerschner et

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al., 2007; Ruhl et al., 2009; Schootbrugge et al., 2009). As noted by Schootbrugge et al.

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Figure 4 Biostratigraphic correlation of the Newark Supergroup section from the Late Triassic through theTriassic−Jurassic boundary. Note unconformities indicated by missing conchostracan zones. Modified from Kozur and Weems (2010), Lucas et al. (2012) and Weems and Lucas (2015). (2009), however, occurrences of a fern-dominated flora at the level of this apparent palynological turnover are limited strictly to the Northern Hemisphere. This palynofloral change has been referred to as the “T-J palynofloral turnover” (Whiteside et al., 2007) or the “Passaic palynofloral event” (Lucas and Tanner, 2007b). But, as KozurACCEPTED and Weems (2005: 33) well observed, “there are no age-diagnostic sporomorphs or other fossils to prove that this extinction event occurred at the Triassic−Jurassic boundary.” Indeed, Kuerschner et al. (2007) concluded that the Newark palynological event most likely represents an older, potentially early Rhaetian event, a

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conclusion shared by Kozur and Weems (2005, 2007, 2010) and by Lucas and Tanner (2007b). Thus, the palynological turnover in the Newark preceded the TJB (Figure 4) and was a palaeogeographically regional event, not a global mass extinction. Bonis and Kürschner (2012) provided a comprehensive review of TJB palynological records to conclude that they indicate vegetation changes that are non- uniform (different changes in different places), not synchronous and not indicative of a mass extinction of land plants. They attributed these changes to climate change driven by CAMP volcanism that produced a warmer climate and stronger monsoonal flow across Pangea, which developed drier interiors and wetter coastal regions. As they well put it, “…instead of a major and globally consistent palynofloral extinction event, the Tr/J boundary is characterized by climate-induced quantitative changes in the sporomorph assemblages that vary regionally in magnitude and composition” (Bonis and Kürschner, 2012: 256). In sum, there is no evidence of a global mass extinction of land plants at the TJB.

5 Tetrapods MANUSCRIPT 5.1 Overview

The idea of a substantial nonmarine tetrapod extinction at the TJB began with Colbert (1949, 1958), and has been more recently advocated by Olsen et al. (1987, 1990, 2002a, 2002b). Nevertheless, Weems (1992), Benton (1994), Lucas (1994), Tanner et al. (2004) and Lucas and Tanner (2004, 2007b, 2008) rejected this conclusion. Colbert (1958) concluded that the temnospondyl amphibians, a significant component of many late Paleozoic and Early−Middle Triassic tetrapod assemblages, underwent complete extinction at the TJB. However, these temnospondyls are only a minor component of Late Triassic tetrapod assemblages, being of low diversity and relatively smallACCEPTED numbers in most stratigraphic units (e.g., Hunt 1993; Long and Murry, 1995). Moreover, current data demonstrate the disappearance of most of the temnospondyls--capitosaurids, metoposaurids and latiscopids--at or just before the Norian-Rhaetian boundary, and only one family extinct at the end of the Triassic

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(plagiosaurids) (Milner, 1993, 1994; Schoch and Milner, 2000). Late Triassic temnospondyl extinctions thus largely preceded the TJB. To Colbert (1958), the bulk of the TJB tetrapod extinction was in the disappearance of the “thecodonts.” These “thecodonts” were more recently referred to as the crurotarsans (phytosaurs, aetosaurs and rauisuchians), though that name is no longer advocated by the latest cladistic analysis (Nesbitt, 2011). Phytosaurs, aetosaurs and rauisuchians are the only members of Colbert’s “thecodonts” to have a substantial Norian or younger fossil record based on current data. Other groups of thecodonts that have been portrayed by some as going extinct at the TJB either lack Rhaetian records (for example, the Ornithosuchidae: Baczko and Ezcurra, 2013) or have so-called Rhaetian records of problematic age, such as records from British fissure-fill deposits (e.g., Fraser, 1994). A non-“thecodont” group that did go extinct during the Rhaetian is the Procolophonidae (Figure 5). However, procolophonids were a group of low diversity by Norian time, and many of their so-called Rhaetian records are from British fissure fills (e.g., Fraser, 1994). The tetrapod taxa from these fissure fills are mostly endemic taxa of no biochronological significance or cosmopolitan taxa with long stratigraphic ranges. As Lucas and Hunt (1994: 340) noted, “a single age MANUSCRIPT should not necessarily be assigned to the fossils from one fissure and....individual fossils from the fissures may range in age from middle Carnian to Sinemurian.” We thus regard as problematic the precise age of many of the Triassic tetrapod fossils from the British fissure fills.

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Figure 5 Stratigraphic ranges of tetrapod footprint ichnogenera and body fossil taxa across the Late Triassic (Rhaetian) Passaic palynofloral event in the Newark section. Modified and updated after Olsen et al. (2002a).

Phytosaur fossils are known from Rhaetian-age strata in the Newark section, the Glen Canyon Group and the Germanic basin (e.gMANUSCRIPT., Lucas and Tanner, 2007a; Olsen et al., 2002a, 2002b; Stocker and Butler, 2013). A Lower Jurassic phytosaur record has been documented by Maisch and Kapitzke (2010). This is an unabraded snout fragment found in the lowermost Jurassic pre-planorbis beds (Neophyllites zone) at Watchet in England. Stocker and Butler (2013) expressed skepticism about the stratigraphic provenance of this record, and it may be a reworked fossil, a possibility difficult to test. We accept that it documents phytosaur persistence into the earliest Jurassic, contradicting the longstanding assumption of their extinction at the TJB. There are no demonstrable aetosaur or rauisuchian body fossils in Rhaetian strata (Desojo et al., 2013; Lucas, 2010b; Nesbitt et al., 2013), though Nesbitt et al. (2013) mentioned a possible Early Jurassic rauisuchian from southern Africa, based on a single snout fragmentACCEPTED that they also stated may be of a large crocodylomorph. Aetosaur and rauisuchian body fossil records thus suggest their extinction before Rhaetian time. Nevertheless, the footprint ichnogenus Brachychirotherium is known from Rhaetian strata, and Lucas and Heckert (2011) argued that an aetosaur was the trackmaker. Note that Smith et al. (2009) reported what they identified as chirothere

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tracks from the Lower Jurassic Elliot Formation of Lesotho in southern Africa, but as Klein and Lucas (2010) noted, these tracks differ from chirothere footprints in significant ways and are more likely large crocodylomorph tracks. The available stratigraphic data thus suggest a three step extinction of the “crurotarsans”—first, rauisuchians by the end of the Norian, second, aetosaurs (based on the footprint ichnogenus Brachychirotherium) by the end of the Rhaetian and third, phytosaurs in the early Hettangian (Figure 6).

MANUSCRIPT

Figure 6 Some biotic events across theTriassic−Jurassic boundary.

Synapsids of the Late Triassic are dicynodonts and cynodonts (e. g., Abdala and Ribeiro, 2010;ACCEPTED Lucas and Hunt, 1994; Lucas and Wild, 1995). Most Late Triassic dicynodont records are Carnian, with a couple of post-Carnian records as young as late Norian (Dzik et al. 2008; Lucas, 2015; Lucas and Wild, 1995; Szulc et al., 2015). The Late Triassic cynodont record is more extensive, especially in Gondwana. Traversodontids have a relatively diverse record in the Carnian-Norian and a single

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Rhaetian record (note that the Gondwana cynodont-bearing strata assigned a Rhaetian age by Abdala and Ribeiro, 2010 are actually Norian: Lucas, 2010b). Trithelodontids cross the TJB, and a problematic group of tooth-based taxa, the “dromatheriids,” disappears in the Rhaetian (Lucas and Hunt, 1994). Note, though, that the origin and diversification of mammaliaforms, which likely include the “dromatheriids,” began in the Late Triassic (e.g., Newham et al., 2014). On present evidence, a TJB synapsid extinction is thus of a handful of taxa, with most taxa extinct by Rhaetian time, but others crossing the TJB.

5.2 Newark tetrapod record

The recent case for a mass extinction of tetrapods at the TJB has relied heavily on the Newark Supergroup record of tetrapod fossils (e.g., Olsen and Sues 1986; Olsen et al., 1987, 1990, 2002a, 2002b; Szajna and Silvestri 1996; Silvestri and Szajna, 1993) (Figure 5). However, a close examination of all Triassic tetrapod taxa known from the Newark Supergroup identifies only three body-fossil taxa (indeterminate phytosaurs, the procolophonid Hypsognathus and sphenodontians) in the youngest Triassic strata, which are strata of Rhaetian age (Huber et al., 1993; MANUSCRIPT Kozur and Weems, 2010; Lucas and Huber, 2003). Recent collecting has not changed that, and only a few fragmentary tetrapod fossils are known from the Newark extrusive zone and are not age diagnostic (Lucas and Huber, 2003; Lucas and Tanner, 2007b). The McCoy Brook Formation, which overlies the only CAMP basalt of the Fundy basin in Nova Scotia, yields a tetrapod assemblage generally considered Early Jurassic in age by vertebrate paleontologists (Fedak et al., 2015; Lucas, 1998; Lucas and Huber, 2003; Lucas and Tanner, 2007a, 2007b; Olsen et al., 1987; Shubin et al., 1994). However, this assemblage could straddle the marine-defined TJB given that Cirilli et al. (2009) demonstrated that at least the lowermost McCoy Brook strata (lower part of Scots Bay Member)ACCEPTED are Rhaetian. Indeed, very recently, Sues and Olsen (2015) and Fedak et al. (2015) have assigned a latest Triassic (Rhaetian) age to an assemblage of vertebrate fossils from the “fish bed” in the Scots Bay Member of the McCoy Brook Formation that includes the crocodylomorph Protosuchus and the tritylodont Oligokyphus. These two taxa are known

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only from Jurassic strata elsewhere (e.g., Lucas and Tanner, 2007a), and their assignment to the Rhaetian is based on inferred cyclostratigraphic correlations (Sues and Olsen, 2015), not on direct association with Triassic fossils. Therefore, we question the age assignment of the “fish bed” to the Triassic, though we also note that if correctly assigned a Rhaetian age, it pushes the temporal record of Protosuchus and of Oligokyphus back into the Triassic, thus diminishing the apparent turnover in tetrapod taxa across the TJB. Because the Newark body fossil record of tetrapods is sparse across the TJB and inadequate to evaluate a possible tetrapod extinction, the tetrapod footprint record in the Newark Supergroup has been used as a proxy (e.g., Olsen and Sues, 1986; Olsen et al., 2002a,2002b; Szajna and Silvestri, 1996). However, detailed stratigraphic study of the Newark footprint record indicates nothing more than moderate turnover in the footprint assemblage at a within-Rhaetian stratigraphic level below the lowest CAMP basalt sheet (Figure 5). Similar changes in tetrapod footprint assemblages are also known from the Chinle Group-Glen Canyon Group section of the American Southwest and from the Germanic Basin (e. g., Lucas et al., 2006a; Lucas, 2007). The footprint turnover in the Newark section (Figure 5) is supposedly the disappearance of four ichnogenera in the uppermostMANUSCRIPT Passaic Formation, and the appearance of three ichnogenera at that datum (Olsen et al., 2002a, 2002b). The ichnogenera that disappear represents phytosaurs (Apatopus: Klein and Lucas, 2013), aetosaurs (Brachychirotherium: Lucas and Heckert, 2011) and tanystropheids (Gwynnedichnium: Lucas et al., 2014). There are single Newark records of Procolophonichnium (procolophonid: Baird, 1986) just below the turnover level and a single record of Ameghinichnus (mammaliaform: Valais, 2009) above the level. According to Olsen et al. (2002a, 2002b), the ornithischian dinosaur footprint ichnogenus Anomoepus first appears at this level, but a later detailed review of the ichnogenus by Olsen and Rainforth (2003) indicated that the lowest stratigraphic record of AnomoepusACCEPTED is stratigraphically higher, in the Newark extrusive zone (Figure 5). The crocodylomorph footprint ichnogenus Batrachopus appears at the turnover level, but there are older Triassic body fossil records of crocodylomorphs (Klein and Lucas, 2010; Nesbitt, 2013). Olsen et al. (2002a, 2002b) showed the prosauropod-dinosaur-footprint ichnogenus Otozoum appearing in the upper Passaic Formation, but a later revision of the

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ichnogenus by Rainforth (2003) established its stratigraphically lowest record as Jurassic, in the Newark extrusive zone (Figure 5). The lacertoid footprint ichnogenus Rhynchosauroides has its last Newark record in the upper Passaic Formation, but this ichnogenus has Jurassic records elsewhere (Avanzini et al., 2010). Thus, what the Newark tetrapod footprint and body-fossil record shows is the local extinction of phytosaurs (they have a younger record elsewhere), aetosaurs, tanystropheids and procolophonids (this may be the level of their global extinction). That is the extent of the turnover in tetrapod taxa it documents, and the turnover level in the Newark is at a Rhaetian horizon, not at the TJB (Figure 5). Part of the footprint turnover in the Newark section is the local lowest occurrence of the theropod footprint ichnogenus Eubrontes (as defined by Olsen et al., 1998, i.e., tridactyl theropod pes tracks longer than 28 cm). For decades, much was made of this record of Eubrontes. Thus, Olsen and Galton (1984) concluded that the lowest occurrence of Eubrontes marks the base of the Jurassic, and Olsen et al. (2002a, 2002b) later argued that the sudden appearance of Eubrontes in the “earliest Jurassic” strata of the Newark Supergroup indicates a dramatic size increase in theropod dinosaurs at the TJB. They interpreted this as the result of a rapid (thousands MANUSCRIPT of years) evolutionary response by the theropod survivors of a mass extinction and referred to it as “ecological release” (Olsen et al., 2002a: 1307). They admitted that this can be invalidated by the description of Dilophosaurus-sized theropods or diagnostic Eubrontes tracks in verifiably Triassic-age strata. Indeed, tracks of large theropod dinosaurs assigned to Eubrontes (or its possible synonym Kayentapus) are known from the Triassic of Australia, Africa (Lesotho), Europe (Great Britain, France, Italy, Germany, Poland-Slovakia, Scania) and eastern Greenland, invalidating the “ecological release” hypothesis (Bernardi et al. 2013; Lucas et al., 2006b; Niedźwiedzki, 2011;). A detailed review of these records indicates Carnian, Norian and ACCEPTED Rhaetian occurrences of tracks that meet the definition of Eubrontes established by Olsen et al. (1998). Also, theropods large enough to have made at least some Eubrontes-size tracks have long been known from the Late Triassic body-fossil record (e.g., Langer et al., 2009). Thus, the sudden abundance of these tracks in the Newark Supergroup cannot be explained simply by the rapid evolution of small

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theropods to large size following a mass extinction. The concept of a sudden appearance of Eubrontes tracks due to “ecological release” at the TJB thus proposed by Olsen et al. (2002a, 2002b) can be abandoned.

5.3 Conclusions

With new and more detailed stratigraphic data, the long perceived TJB tetrapod extinction looks mostly like an artifact of coarse temporal resolution, the compiled correlation effect of Lucas (1994). Thus, Colbert (1958) knew, and we still know, that Late Triassic tetrapod assemblages in Laurussian locales are dominated by phytosaurs, with lesser numbers of aetosaurs, rauisuchians and dinosaurs. Some Gondwanan Late Triassic assemblages are cynodont (mostly traversodontid) and rhynchosaur dominated. In contrast, well known Early Jurassic tetrapod assemblages are dinosaur dominated, with lesser numbers of crocodylomorphs and cynodonts (tritylodontids), and no phytosaurs, aetosaurs or rauisuchians. But, the former are Norian, and the latter are Sinemurian age assemblages, separated in time by at least 6 million years. Given the lack of evidence for TJB plant and arthropod extinctions, what could have caused a TJB tetrapod extinction? Aetosaurs, MANUSCRIPT some of the cynodonts and all of the dicynodonts perceived of as suffering extinction are inferred herbivores, whereas the phytosaurs and rauisuchians are inferred predators. Given that many herbivores—notably the prosauropod dinosaurs—continue through the TJB, a sudden trophic collapse of vertebrate communities on land cannot be supported. Instead, the extinctions of tetrapods during the Late Triassic appear to be a prolonged series of events that began in the Norian and extended into the Hettangian (Figure 6).

6 Ecological severity McGheeACCEPTED et al. (2004, 2013) argued that mass extinctions need to be evaluated not just as biodiversity crises (crashes), but also in terms of their ecological severity. In their scheme of ecological severity, they considered the TJB nonmarine extinction to be in their category I or IIa. Category I means that ecosystems before the extinction were replaced by new ecosystems post-extinction, whereas category IIa means that the

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extinctions caused permanent loss of major ecosystem components. Clearly, as we have pointed out earlier (Lucas and Tanner, 2008), this is a gross overestimate of the ecological significance of whatever extinctions took place on land across the TJB. McGhee et al. (2004) concluded that the TJB involved a rapid ecological replacement of Triassic mammal-like reptiles and rhynchosaurs by dinosaurs. However, the stratigraphically highest rhynchosaurs are Revueltian (early-middle Norian), and the group was largely gone by the end of the Carnian (Hunt and Lucas, 1991; Lucas et al., 2002; Spielmann et al., 2013). Late Norian dicynodonts are now known (Dzik et al., 2008; Szulc et al., 2015) and document a small presence in the post Carnian, unless a putative Cretaceous record (with problematic provenance) from Australia is verified (Thulborn and Turner, 2003). The other principal group of Late Triassic mammal-like reptiles, the cynodonts, were of low diversity after the Carnian-Norian (Abdala and Ribeiro, 2010; Lucas and Hunt, 1994). Dinosaurs appeared as body fossils in the Carnian and began to diversify substantially in some parts of Pangea by the late Norian (e.g., Langer, 2014; Langer et al., 2009). Thus, the ecological severity of the end-Triassic tetrapod extinction is relatively low (Category IIb on the McGhee et al., 2004 classification),MANUSCRIPT and the plant extinctions do not look like they were ecologically severe either (see above). Clearly, there was no substantial disruption of the terrestrial ecosystem (excluding some local perturbations) across the TJB.

7 The role of CAMP volcanism

In the marine realm, the end-Triassic drop in diversity was selective but notable for the rapid loss of specific taxa, such as conodonts, radiolarians, infaunal bivalves and ammonoids, suggesting physical processes that strongly affected ocean bioproductivity (Tanner et al., 2004). For many years, the hypothesis was advanced that the extinctions were associatedACCEPTED with a single catastrophic cause, specifically, the Manicouagan bolide impact, the remnant crater of which spans ~ 70 km in southern Quebec, Canada (Olsen et al., 1987, 2002a, 2002b). However, this hypothesis was firmly disproved by radioisotopic

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dating of the Manicouagan structure, which showed that the impact occurred ~ 14 Ma prior to the TJB (Hodych and Dunning, 1992; Onoue et al., 2012; Ramezani et al., 2005). Subsequently, attention on the TJB “extinctions” has focused primarily on the environmental effects of the eruption of the flood basalts of the Central Atlantic Magmatic Province (CAMP). Formerly, the onset of CAMP eruptive activity was assumed to post-date the TJB (Whiteside et al., 2007), but it is now well-established that these eruptions span the boundary (Cirilli et al., 2009; Kozur and Weems, 2005, 2007, 2010; Lucas and Tanner, 2007b). Within the basins of the Newark Supergroup, the eruptions proceeded in three main episodes, separated by eruptive hiatuses during which sediments accumulated, with the majority of the total volume ejected during the initial eruptive episode (Marzoli et al., 2011). The total duration of the CAMP eruptions has been estimated at ~600 ky by cyclostratigraphy (Olsen et al., 1996). The initial estimate of the size of the province, by McHone and Puffer (1996), was ~2.3 x 106 km2, but Deckart et al. (1997) and Marzoli et al. (1999) extended the boundaries of the province to include all areas near the rift margin containing mafic intrusions of approximately correlative age, ultimately outlining an area of 11 x 106 km2. Defining the vast potential aerial MANUSCRIPT extent of CAMP led to an erupted lava volume calculation of ~2 x 106 km3, similar to the volume calculated for the Deccan Traps. As noted by Tanner et al. (2004), however, this calculation entails the assumption that the entire area was covered by lava to an average depth of hundreds of meters. Even in the Newark basin, however, where the entire erupted thickness is preserved, the total thickness varies widely, from > 1 km to as little as tens of meters. Therefore, we regard this assumption as untenable. It is widely acknowledged that floral and faunal turnover at the end of the Triassic was likely driven by the CAMP eruptions, which caused a significant environmental perturbation through outgassing (e. g., Belcher et al., 2010; Blackburne et al., 2013; Bonis et al., ACCEPTED2009; Haworth and Raschi, 2014; Ruhl et al., 2010; Schoene et al., 2010; Schootbrugge et al., 2008; Tanner et al., 2004). Attention has focused largely on the potential for greenhouse warming produced by the outgassed CO2 (Berner and Beering, 2002; McElwain et al., 1999; Steinthorsdottir et al., 2011), but many of these studies ignore the constraints of the likely volume of erupted lava and gas content. Yapp and

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Poths (1996), for example, estimated a catastrophic 18-fold increase in atmospheric CO2 across the TJB, whereas Tanner et al. (2001) calculated a much more modest increase (of several hundred ppm), and more recently, Steinthorsdottir et al. (2011) calculated a CO2 doubling (by 2000 to 2500 ppm). The tremendous divergence in the published estimates of atmospheric CO2 loading from CAMP outgassing stems from the different approaches used to generate the calculations. McElwain and collaborators (e.g., McElwain et al., 1999; Steinthorsdottir et al., 2011) rely primarily on the stomatal response of plants to elevated CO2 levels, while others (Cleveland et al., 2008; Schaller et al., 2012; Tanner et al., 2001) utilize the isotopic composition of pedogenic carbonates. These approaches also yield diverging estimates for the pre-eruption atmospheric composition, knowledge of which is essential to determining the warming effects of CAMP outgassing. Thus, there is as yet no agreement on the mass of CO2 released by the CAMP eruptions, much less agreement on the climatic consequences. Tanner et al. (2004, 2007) drew attention to the lack of consideration of the effects of SO2 outgassing by the CAMP eruptions, and further demonstrated that high atmospheric SO2 loading also can force changes in plant stomatal frequency, an effect eventually noticed by other workers (Bacon et MANUSCRIPT al., 2013). The environmental effects of large sulfur emissions during prolonged flood basalt eruptions are not clear, but the formation of H2SO4 aerosols, which in addition to causing acidic precipitation, are known to increase atmospheric opacity and result in reduced short-wave radiant heating, causing global cooling (Sigurdsson, 1990). Fluorine and chlorine volatile emissions during the CAMP eruptions also would have contributed to the acidification of surface waters and terrestrial environments (Guex et al., 2004; Lucas and Tanner, 2008; Schootbrugge et al., 2009). Thus, a temporary loss of phytoplankton productivity in marine surface waters is an entirely reasonable consequence of the CAMP eruptions. The subsequent “trickle- down” effectsACCEPTED through the marine trophic system are clear, even without climate change. Primary producers would have been most profoundly affected by the changes in water chemistry, but higher level consumers would also have felt ecological pressure, although perhaps less strongly. The compounding effects of climate change – rapid, short-term cooling forced by H2SO4 aerosols and slower, longer-term warming driven by CO2 –

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would have exacerbated the environmental stresses on the ecosystems. Thus, floral and faunal turnover at the end of the Triassic was likely driven by the CAMP eruptions, which caused significant environmental perturbations (cooling, warming, acidification) through outgassing, but the effects on the nonmarine biota appear to have been palaeogeographically localized, transient and not catastrophic.

8 End Triassic nonmarine biotic events

The Late Triassic was a time of elevated extinction rates and low origination rates in many biotic groups (e.g., Bambach et al., 2004; Kiessling et al., 2007; Lucas and Tanner, 2008). Most of the evidence for this comes from the marine biota, with multiple Late Triassic, and often substantial extinctions of radiolarians, conodonts, bivalves, ammonoids and reef-building organisms. In the marine realm, these events are: (1) early- middle Carnian boundary (the “Carnian crisis”), which included major extinctions of crinoids (especially the Encrinidae), echinoids, some bivalves (scallops), bryozoans, ammonoids, conodonts and a major change in the reef ecosystem; (2) a substantial extinction of conodonts, ammonoids and someMANUSCRIPT bivalves (especially pectinids) at the Carnian-Norian boundary; (3) within and at the end of the Norian, when there are several extinction events that had a particularly profound effect on conodonts, marine bivalves and ammonoids; and (4) a final set of stepwise extinctions, particularly of ammonoids and conodonts, within and at the end of the Rhaetian. (e.g., Flügel, 2002; Hallam, 1995; Hornung et al., 2007; Johnson and Simms, 1989; Lucas and Tanner, 2008; Schäfer and Fois, 1987; Tanner et al., 2004) On land, plant and tetrapod extinctions were much less dramatic. Within the Carnian most workers envision a humid phase (or “pluvial”) as a possible cause of some turnover of terrestrial taxa, at least in Europe (e.g., Hornung et al., 2007; Rigo et al., 2007; Simms and Ruffell, 1989, 1990), though this has been disputed (e.g., Visscher et al., 1994). ThereACCEPTED is an end-Carnian event in the terrestrial tetrapod record, with some evolutionary turnover across the Carnian-Norian boundary (Benton, 1986, 1991, 1993; Lucas, 1994). Extinctions on land closer to the TJB look even less significant. The amphibian, archosaur and synapsid extinctions of the Late Triassic are not concentrated

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at the TJB, but instead occur stepwise, beginning in the Norian and extending into the Jurassic (Figure 6). Changes in the land plants are complex, diachronous and likely climate driven evolutionary changes over background extinction rates, not a serious extinction or set of extinctions. We conclude that no significant extinction took place on land at the TJB. Indeed, the idea of a single mass extinction on land at the TJB has led to a search for the cause of the “mass extinction” and drawn attention away from what were actually a series of biotic events that took place throughout the Late Triassic (Figure 6). Research should now focus on these multiple extinctions and their causes, not on a single extinction event. Perhaps the most interesting question not yet addressed by most researchers is why a prolonged (at least 30 million years) interval of elevated extinction rates occurred during the Late Triassic.

Acknowledgments

We are grateful to Baas van de Schootbrugge for encouraging us to publish this article. We also thank Professor Li, Jin-Geng Sha,MANUSCRIPT Shu-Zhong Shen and two anonymous reviewers for their helpful reviews of this article.

References

Abdala, F., Ribeiro, A. M., 2010. Distribution and diversity patterns of Triassic cynodonts (Therapsida, Cynodontia) in Gondwana. Palaeogeography, Palaeoclimatology, Palaeoecology, 286, 202-217. Ash, S., 1986. Fossil plants and the Triassic-Jurassic boundary. In: Padian, K. (Ed.), The beginning of the age of dinosaurs. Cambridge University Press, Cambridge, pp. 21-30. Avanzini, M., Pinuela, L., Garcia-Ramos, J. C., 2010. First report of a Late Jurassic lizard-like footprint (Asturias, Spain). Journal of Iberian Geology, 36, 175-180.

Bacon, K. L., Belcher,ACCEPTED C. M., Haworth, M., McElwain, J. C., 2013. Increased atmospheric SO2 detected from changes in leaf physiognomy across the Triassic-Jurassic boundary interval of East Greenland. PLOS One, 8(4), e60614. Baczko, M. B. von, Ezcurra, M. D., 2013. Ornithosuchidae: A group of Triassic archosaurs with a unique ankle joint. In: Nesbitt, S. J. Desojo, J. B., Irmis, R. B., (Eds.). Anatomy, phylogeny

29 ACCEPTED MANUSCRIPT

and palaeobiology of Early Archosaurs and their kin. Geological Society, London, Special Publications, 379, 187-202. Baird, D., 1986. Some Upper Triassic reptiles, footprints, and an amphibian from New Jersey. The Mosasaur, 3, 125-153. Balini, M., Lucas, S. G., Jenks, J. M., Spielmann, J. A., 2010. Triassic ammonoid biostratigraphy: An overview. In: Lucas, S. G. (Ed.), The Triassic timescale. Geological Society, London, Special Publication, 334, 221-262. Bambach, R. K., Knoll, A. H., Wang, S. C., 2004. Origination, extinction, and mass depletion of marine diversity. Paleobiology, 20, 522-542. Bandyopadhyay, S., Sengupta, D. P., 2006. Vertebrate faunal turnover during the Triassic-Jurassic transition: An Indian scenario. New Mexico Museum of Natural History and Science Bulletin, 37, 77-85. Belcher, C. M., Mander, L., Rein, G., Jervis, F. X., Haworth, M., Hesselbo, S. P., Glasspool, I. J., McElwain, J. C., 2010. Increased fire activity at the Triassic/Jurassic boundary in Greenland due to climate-driven floral change. Nature Geoscience, 3, 426-429. Benton, M. J., 1986. More than one event in the Late Triassic mass extinction. Nature, 321, 857-861. Benton, M. J., 1991. What really happened in the Late Triassic? Historical Biology, 5, 263-278. Benton, M. J., 1993. Reptilia. In: Benton, M. J., (Ed.), The fossil record 2. Chapman and Hall, London, 681-715. MANUSCRIPT Benton, M. J., 1994. Late Triassic to Middle Jurassic extinctions among continental tetrapods: Testing the pattern. In: Fraser, N. C., Sues, H-D., (Eds.), In the shadow of the dinosaurs. Cambridge University Press, Cambridge, 366-397.

Berner, R. A., Beerling, D. J., 2007. Volcanic degassing necessary to produce CaCO3 undersaturated ocean at the Triassic–Jurassic boundary. Palaeogeography, Palaeoclimatology, Palaeoecology, 244, 368-373. Bernardi, M., Petti, F. M., Porchetti, S.D., Avanzini, M., 2013. Large tridactyl footprints associated with a diverse ichnofauna from the Carnian of the Southern Alps. New Mexico Museum of Natural History and Science Bulletin, 61, 48-54. Blackburn, T J., Olsen, P. E., Bowring, S. A., McLean, N. M., Kent, D. V., Puffer, J., McHone, G., Rasbury, E. T., Et-Touhami, M., 2013. Zircon U-Pb geochronology links theACCEPTED end-Triassic extinction with the Central Atlantic Magmatic Province. Science, 340, 941-945. Bonis, N. R., Kürschner, W. M., 2012. Vegetation history, diversity patterns, and climate change across the Triassic/Jurassic boundary. Paleobiology, 38, 240-264.

30 ACCEPTED MANUSCRIPT

Bonis, N. R., Kürschner, W., Krystyn, L., 2009. A detailed palynological study of the Triassic-Jurassic transition in key sections of the Eiberg basin (Northern calcareous Alps, Austria). Review of Palaeobotany and Palynology, 156, 376-400. Brugman, W. A., 1983. Permian-Triassic Palynology. State University Utrecht, Utrecht, 1-121. Burgoyne, P. M., van Wyk, A. E., Anderson, J. M., Schrire, B. D., 2005. Phanerozoic evolution of plants on the African plate. Journal of African Earth Sciences, 43, 13-52. Cascales-Miñana, B., Cleal, C. J., 2011. Plant fossil record and survival analysis. Lethaia, 45, 71-82. Cirilli, S., 2010. Uppermost Triassic-lowermost Jurassic palynology and palynostratigraphy: A review. In: Lucas, S. G., (Ed.), The Triassic timescale. Geological Society, London, Special Publication, 334, 285-314. Cirilli, S., Marzoli, A., Tanner, L. H., Bertrand, H., Buratti, N., Jourdan, F., Bellieni, G., Kontak, D., Renne, P. R., 2009. Late Triassic onset of the Central Atlantic Magmatic Province (CAMP) volcanism in the Fundy Basin (Nova Scotia): New stratigraphic constraints. Earth and Planetary Science Letters, 286, 514-525. Cleal, C. J., 1993a. Pteridophyta. In: Benton, M. J., (Ed.), The fossil record 2. Chapman and Hall, London, 779-794. Cleal, C. J., 1993b. Gymnospermophyta; In: Benton, M. J., (Ed.), The fossil record 2. Chapman and Hall, London, 795-808. Cleveland, D.M., Nordt, L.C., Dworkin, S.I., Atchley, MANUSCRIPTS.C., 2008. Pedogenic carbonate isotopes as evidence for extreme climatic events preceding the Triassic-Jurassic boundary: Implications for the biotic crisis? GSA Bulletin, 120, 1408-1415. Colbert, E.H., 1949. Progressive adaptations as seen in the fossil record. In: Jepsen, G. L., Mayr, E., Simpson, G. G., (Eds.), Genetics, paleontology and evolution. Princeton University Press, Princeton, pp. 390-402. Colbert, E.H., 1958. Triassic tetrapod extinction at the end of the Triassic Period. Proceedings National Academy of Science USA, 44, 973-977. Cornet, B., 1977. The Palynostratigraphy and Age of the Newark Supergroup. Ph.D. Thesis. Pennsylvania State University, University Park, PA, 1-505. Cornet, B., Olsen, P.E., 1985. A summary of the biostratigraphy of the Newark Supergroup of eastern North America with comments on provinciality. In: Weber, R., (Ed.), III Congreso LatinoamericanoACCEPTED de Paleontologia Mexico, Simposio Sobre Floras del Triasico Tardio, su Fitogeografia y Paleoecologia, UNAM Instituto de Geologia, Mexico City, pp. 67-81. Dam, G., Surlyk, F., 1993. Cyclic sedimentation in a large wave- and storm-dominated anoxic lake, Kap Stewart Formation (Rhaetian-Sinemurian), Jameson Land, East Greenland. International Association of Sedimentologists Special Publication, 18, 419-448.

31 ACCEPTED MANUSCRIPT

Deckart, K., Fèraud, G., Bertrand, H., 1997. Age of Jurassic continental tholeiites of French Guyana, Surinam and Guinea: Implications for the initial opening of the Central Atlantic Ocean. Earth and Planetary Science Letters, 150, 205-220. Desojo, J. B., Heckert, A. B., Martz, J. W., Parker, W. G., Schoch, R. R., Small, B. J., Sulej, T., 2013. Aetosauria: A clade of armoured pseudosuchians from the Upper Triassic continental beds. In: Nesbitt, S. J. Desojo, J. B., Irmis, R. B., (Eds.), Anatomy, phylogeny and palaeobiology of early archosaurs and their Kin. Geological Society, London, Special Publications, 379, 203- 240. Dzik, J., Sulej, T., Niedzwiedzki, G., 2008. A dicynodont-theropod association in the latest Triassic of Poland. Acta Palaeontologica Polonica, 53, 733–738. Edwards, D., 1993. Bryophyta. In: Benton, M. J., (Ed.), The fossil record 2. Chapman and Hall, London, 775-778. Fedak, T. J., Sues, H.-D., Olsen, P. E., 2015. First record of the tritylodontid cynodont Oligokyphus and cynodont postcranial bones from the McCoy Brook Formation of Nova Scotia, Canada. Canadian Journal of Earth Sciences, 52, 244-249. Fisher, M. J., Dunay, R.E., 1981. Palynology and the Triassic/Jurassic boundary. Review of Palaeobotany and Palynology, 34, 129-135. Flügel, E., 2002. Triassic reef patterns. In: Kiessling, W., Flügel, E., Golonka, J., (Eds.), Phanerozoic reef patterns, SEPM Special Publication, 72, 391-463.MANUSCRIPT Fowell, S.J., Olsen, P.E., 1993. Time calibration of Triassic-Jurassic microfloral turnover, eastern North America. Tectonophysics, 222, 361-369. Fowell, S. J., Traverse, A., 1995. Palynology and age of the upper Blomidon Formation, Fundy basin, Nova Scotia. Review of Palaeobotany and Palynology, 86, 211-233. Fowell, S. J., Cornet, B., Olsen, P.E., 1994. Geologically rapid Late Triassic extinctions: palynological evidence from the Newark Supergroup. Geological Society of America Special Paper, 288, 197-206. Fraser, N. C., 1994. Assemblages of small tetrapods from British Late Triassic fissure deposits. In: Fraser, N. C., Sues, H-D., (Eds.), In the shadow of the dinosaurs. Cambridge University Press, Cambridge, pp. 214-226. Galli, M. T., Jadoul, F., Bernasconi, S. M., Weissert, H., 2005. Anomalies in global carbon cycling and extinctionACCEPTED at the Triassic/Jurassic boundary: Evidence from a marine C-isotope record. Palaeogeography, Palaeoclimatology, Palaeoecology, 16, 203-214. Giordano, N., Rigo, M., Ciarapica, G., Bertinelli, A., 2010. New biostratigraphical constraints for the Norian/Rhaetian boundary: Data from Lagonegro basin, Southern Appenines, Italy. Lethaia, 43, 573-586.

32 ACCEPTED MANUSCRIPT

Gómez, J. J., Goy, A., Barrón, E., 2007. Events around the Triassic-Jurassic boundary in northern and eastern Spain: A review. Palaeogeography, Palaeoclimatology, Palaeoecology, 244, 89-110. Grimaldi, D., Engel, M. S., 2005. Evolution of the Insects. Cambridge University Press, Cambridge, pp. 1-755. Guex, J., Bartolin, A., Atudorei, V., Taylor, D., 2004. High-resolution ammonite and carbon isotope stratigraphy across the Triassic-Jurassic boundary at New York Canyon (Nevada). Earth and Planetary Science Letters, 225, 29-41. Hallam, A., 1995. Major bio-events in the Triassic and Jurassic. In: Walliser, O., (Ed.), Global events and event stratigraphy. Springer, Berlin, pp. 265-283. Hallam, A., 2002. How catastrophic was the end-Triassic mass extinction? Lethaia, 35, 147-157. Hallam, A., Wignall, P.B., 1997. Mass Extinctions and Their Aftermath. Oxford University Press, Oxford, pp.1-320. Harris, T. M., 1937. The fossil flora of Scoresby Sound East Greenland, Part 5: Stratigraphic relations of the plant beds. Meddelelser om Grønland, 112, 1-112. Haworth, M., Raschi, A., 2014. An assessment of the use of epidermal micro-morphological features to estimate leaf economics of Late Triassic-Early Jurassic fossil Ginkgoales. Review of Palaeobotany and Palynology, 205, 1-8. Hesselbo, S.P., Robinson, S.A., Surlyk, F., Piasecki, S., 2002. Terrestrial and marine extinction at the Triassic-Jurassic boundaryMANUSCRIPT synchronized with major carbon-cycle perturbation: A link to initiation of massive volcanism? Geology, 30, 251-254. Hillebrandt, A. v., Krystyn, L., Kürschner, W. M., Bonis, N. R., Ruhl, M., Richoz, S., Schobben, M. A. N., Ulrichs, M., Bown, P. R., Kment, K., McRoberts, C. A., Simms, M., Tomãsovych, A., 2013. The global stratotype section and point (GSSP) for the base of the Jurassic System at Kuhjoch (Karwendel Mountains, Northern Calcareous Alps, Tyrol, Austria). Episodes, 36, 162-198. Hodych, J. P., Dunning, G. R., 1992. Did the Manicouaga impact trigger end-of-Triassic mass extinction? Geology, 20, 51-54. Hornung, T., Brandner, R., Krystyn, L., Jaochimski, M. M., Keim, L., 2007. Multistratigraphic constrainst on the NW Tethyan “Carnian crisis”. New Mexico Museum of Natural History and ScienceACCEPTED Bulletin, 41: 59-67 Hounslow, M. W., Muttoni, G., 2010. The geomagnetic polarity timescale for the Triassic: Linkage to stage boundary definitions. In: Lucas, S. G., (Ed.), The Triassic Timescale. Geological Society, London, Special Publication, 334, 61-102.

33 ACCEPTED MANUSCRIPT

Hounslow, M. W., Posen, P. E., Warrington, G., 2004. Magnetostratigraphy and biostratigraphy of the Upper Triassic and lowermost Jurassic succession, St. Audrie’s Bay, UK. Palaeogeography, Palaeoclimatology, Palaeoecology, 213, 331-358. Huber, P., Lucas, S. G., Hunt, A. P., 1993. Vertebrate biochronology of the Newark Supergroup Triassic, eastern North America. New Mexico Museum of Natural History and Science Bulletin, 3, 179-186. Hunt, A.P., 1993. A revision of the Metoposauridae (Amphibia: Temnospondyli) of the Late Triassic with description of a new genus from the western United States. Museum of Northern Arizona Bulletin, 59, 67-97. Hunt, A. P., Lucas, S. G., 1991. A new rhynchosaur from West Texas (USA) and the biochronology of Late Triassic rhynchosaurs. Palaeontology, 34, 191-198. Johnson, L.A., Simms, M. J., 1989. The timing and cause of Late Triassic marine invertebrate extinctions: Evidence from scallops and crinoids. In: Donovan, K., (Ed.). Mass extinctions: Processes and evidence, Columbia University Press, New York, pp. 174-194. Kelber, K.-P., 1998. Phytostratigraphische aspekte der makrofloren des süddeutschen Keupers. Documenta Naturae, 117, 89-115. Kiessling, W., Aberhan, M., Brenneis, B., Wagner, P. J., 2007. Extinction trajectories of benthic organisms across the Triassic-Jurassic boundary. Palaeogeography, Palaeoclimatology, Palaeoecology, 244, 201-222. MANUSCRIPT Klein, H., Lucas, S. G., 2010. The Triassic footprint record of crocodylomorphs—A critical re- evaluation. New Mexico Museum of Natural History and Science Bulletin, 51, 55-60. Klein, H., Lucas, S. G., 2013. The Late Triassic tetrapod ichnotaxon Apatopus lineatus (Bock 1952) and its distribution. New Mexico Museum of Natural History and Science Bulletin, 61, 313- 324. Knoll, A. H., 1984. Patterns of extinction in the fossil record of vascular plants. In: Nitecki, M., (Ed.), Extinction. University of Chicago Press, Chicago, pp. 21-68. Kozur, H. W., Bachmann, G. H., 2005. Correlation of the Germanic Triassic with the international scale. Albertiana, 32, 21-35. Kozur, H.W., Bachmann, G.H., 2008. Updated correlation of the Germanic Triassic with the Tethyan scale and assigned numeric ages. Berichte Geologische Bundesanstalt, 76, 53-58. Kozur, H. W., ACCEPTEDWeems, R. E., 2005. Conchostracan evidence for a late Rhaetian to early Hettangian age for the CAMP volcanic event in the Newark Supergroup, and a Sevatian (late Norian) age for the immediately underlying beds. Hallesches Jahrbuch Geowissenschaft, B27, 21-51. Kozur, H. W., Weems, R. E., 2007. Upper Triassic conchostracan biostratigraphy of the continental rift basins of eastern North America: Its importance for correlating Newark Supergroup

34 ACCEPTED MANUSCRIPT

events with the Germanic Basin and the international geologic time scale. New Mexico Museum of Natural History and Science Bulletin, 41, 137-188. Kozur, H. W., Weems, R. E., 2010. The biostratigraphic importance of conchostracans in the continental Triassic of the northern hemisphere. In: Lucas, S. G., (Ed.), The Triassic timescale. Geological Society, London, Special Publication, 334, 315-417. Krystyn, L., Boquerel, H., Kuerschner, W., Richoz, S., Gallet, Y., 2007. Proposal for a candidate GSSP for the base of the Rhaetian Stage. New Mexico Museum of Natural History and Science Bulletin, 41, 189-199. Kürschner, W. M., Herngreen, G. F. W., 2010. Triassic palynology of central and northwestern Europe: A review of palynofloral diversity patterns and biostratigraphic subdivisions. In: Lucas, S. G., (Ed.), The Triassic timescale. Geological Society, London, Special Publication, 334, 263-283. Kuerschner, W. M., Bonis, N. R., Krystyn, L., 2007. Carbon-isotope stratigraphy and palynostratigraphy of the Triassic-Jurassic transition in the Tiefengraben section—Northern Calcareous Alps (Austria). Palaeogeography, Palaeoclimatology, Palaeoecology, 244, 257- 280. Labandeira, C. C., Sepkoski, J. J., Jr., 1993. Insect diversity in the fossil record. Science, 261, 310- 315. Langer, M. C., 2014. The origins of Dinosauria: Much MANUSCRIPTado about nothing. Palaeontology, 2014, 1-10. Langer, M. C., Ezcurra, M. D., Bittencourt, J. S., Novas, F. E., 2009. The origin and early evolution of dinosaurs. Biological Reviews, 84, 1-56. Long, R. A., Murry, P. A., 1995, Late Triassic (Carnian and Norian) tetrapods from the southwestern United States. New Mexico Museum of Natural History and Science Bulletin, 4, 1-254. Lucas, S. G., 1994. Triassic tetrapod extinctions and the compiled correlation effect. Canadian Society of Petroleum Geologists Memoir, 17, 869-875. Lucas, S. G., 1998. Global Triassic tetrapod biostratigraphy and biochronology. Palaeogeography, Palaeoclimatology, Palaeoecology, 143, 347-384. Lucas, S.G., 2007. Tetrapod footprint biostratigraphy and biochronology. Ichnos, 14, 5-38. Lucas, S. G., 2008. Global Jurassic tetrapod biochronology. Volumina Jurassica, 6, 99-108. Lucas, S. G., 2010a. The Triassic timescale: An introduction. In: Lucas, S. G., (Ed.), The Triassic timescale.ACCEPTED Geological Society, London, Special Publication, 334, 1-16. Lucas, S. G., 2010b. The Triassic timescale based on nonmarine tetrapod biostratigraphy and biochronology. In: Lucas, S. G., (Ed.), The Triassic Timescale. Geological Society, London, Special Publication, 334, 447-500. Lucas, S. G., 2013a. Plant megafossil biostratigraphy and biochronology, Upper Triassic Chinle Group, western USA. New Mexico Museum of Natural History and Science Bulletin, 61, 354-365.

35 ACCEPTED MANUSCRIPT

Lucas, S. G., 2013b. A new Triassic timescale. New Mexico Museum of Natural History and Science Bulletin, 61, 366-374. Lucas, S. G., 2015. Age and correlation of Late Triassic tetrapods from southern Poland. Annales Societatis Geologorum Poloniae, in press. Lucas, S. G., Heckert, A. B., 2011. Late Triassic aetosaurs as the trackmaker of the tetrapod footprint ichnotaxon Brachychirotherium. Ichnos, 18, 197-208. Lucas, S. G., Huber, P., 2003. Vertebrate biostratigraphy and biochronology of the nonmarine Late Triassic. In: LeTourneau, P. M., Olsen, P. E., (Eds.), The great rift valleys of Pangea in eastern North America. Volume 2. Sedimentology, Stratigraphy, and Paleontology. Columbia University Press, New York, pp. 143-191. Lucas, S. G., Hunt, A. P., 1994. The chronology and paleobiogeography of mammalian origins. In: Fraser, N. C., Sues, H-D.,(Eds.), In the shadow of the dinosaurs. Cambridge University Press, Cambridge, pp. 335-351. Lucas, S. G., Tanner, L. H., 2004. Late Triassic extinction events. Albertiana, 31, 31-40. Lucas, S. G., Tanner, L. H., 2007a. Tetrapod biostratigraphy and biochronology of the Triassic- Jurassic transition on the southern Colorado Plateau, USA. Palaeogeography, Palaeoclimatology, Palaeoecology, 244, 242-256. Lucas, S. G., Tanner, L. H., 2007b. The nonmarine Triassic-Jurassic boundary in the Newark Supergroup of eastern North America. Earth ScienceMANUSCRIPT Reviews, 84, 1-20. Lucas, S. G., Tanner, L. H., 2008. Reexamination of the end-Triassic mass extinction. In; Elewa, A. M. T., (Ed.), Mass extinction. Springer Verlag, New York, pp. 66-103. Lucas, S. G., Wild, R., 1995. A Middle Triassic dicynodont from Germany and the biochronology of Triassic dicynodonts. Stuttgarter Beiträge zur Naturkunde, 220, 1-16. Lucas, S. G., Heckert, A. B., Hotton, N. III., 2002. The rhynchosaur Hyperodapedon from the Upper Triassic of Wyoming and its global biochronological significance. New Mexico Museum of Natural History and Science Bulletin, 21, 149-156. Lucas, S. G., Hunt, A. P., Heckert, A. B., Spielmann, J. A., 2007a. Global Triassic tetrapod biostratigraphy and biochronology: 2007 status. New Mexico Museum of Natural History and Science Bulletin, 41, 229-240. Lucas, S. G., Lockley, M. G., Hunt, A. P., Milner, A. R. C., Tanner, L. H., 2006a. Tetrapod footprint biostratigraphyACCEPTED of the Triassic-Jurassic transition in the American Southwest. New Mexico Museum of Natural History and Science Bulletin, 37, 105-108. Lucas, S. G., Taylor, D. G., Guex, J., Tanner, L. H., Krainer, K., 2007b. The proposed global stratotype section and point for the base of the Jurassic System in the New York Canyon area, Nevada, USA. New Mexico Museum of Natural History and Science Bulletin, 40, 139-68. Lucas, S.G., Tanner, L.H., Donohoo-Hurley, L.L., Geissman, J.W., Kozur, H.W., Heckert, A.B., Weems,

36 ACCEPTED MANUSCRIPT

R.E., 2011. Position of the Triassic-Jurassic boundary and timing of the end- Triassic extinctions on land: Data from the Moenave Formation on the southern Colorado Plateau, USA. Palaeogeography, Palaeoecology, Palaeoclimatology, 302, 194-205. Lucas, S. G., Tanner, L. H., Kozur, H. W., Weems, R. E., Heckert, A. B., 2012. The late Triassic timescale: Age and correlation of the Carnian-Norian boundary. Earth Science Reviews, 114, 1-8. Lucas, S. G., Klein, H., Lockley, M. G., Spielmann, J. A., Gierlinski, G., Hunt, A. P., Tanner, L. H., 2006b. Triassic-Jurassic stratigraphic distribution of the theropod footprint ichnogenus Eubrontes. New Mexico Museum of Natural History and Science Bulletin, 37, 86-93. Lucas, S. G., Szajna, M. J., Lockley, M. G., Fillmore, D. L., Simpson, E. L., Klein, H. Boyland, J., Hartline, B. W., 2014. The Middle-Late Triassic tetrapod footprint ichnogenus Gwynnedichnium. New Mexico Museum of Natural History and Science Bulletin, 62, 135- 156. Maisch, M. W., Kapitzke, M., 2010. A presumably marine phytosaur (Reptilia: Archosauria) from the pre-planorbis beds (Hettangian) of England. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 257, 373-379. Mander, L., Kürschner, W. M., McElwain, J. C., 2010. An explanation for conflicting records of Triassic-Jurassic plant diversity. Proceedings of the National Academy of Science USA, 107, 15351-15356. MANUSCRIPT Mander, L., Kürschner, W. M., McElwain, J. C., 2013. Palynostratigraphy and vegetation history of the Triassic-Jurassic transition in East Greenland. Journal of the Geological Society London, 170, 37-46. Mander, L., Wesseln, C. J., McElwain, J. C., Punyasena, S. W., 2012. Tracking taphonomic regimes using chemical and mechanical damage of pollen and spores: An example from the Triassic- Jurassic mass extinction. PLos ONE, 7(11), e49153. Marzoli, A., Bertrand, H., Knight, K. B., Cirilli, S., Buratti, N., Verati, C., Nomade, S., Renne, P. R., Youbi, N., Martini, R., Allenbach, N., Neuwerth, R., Rapaille, C., Zaninetti, L., Zaninetti, L., Bellieni, G., 2004. Synchrony of the Central Atlantic magmatic province and the Triassic- Jurassic boundary climate and biotic crisis. GSA Bulletin, 32, 973-976. Marzoli, A., Renne, P.R., Piccirillo, E.M., Ernesto, M., Bellieni, G., DeMin, A., 1999. Extensive 200- million-year-oldACCEPTED continental flood basalts of the central Atlantic Magmatic province. Science, 284, 616-618. Marzoli, A., Jourdan, F. Puffer, J.H., Cuppone, T., Tanner, L.H., Weems, R.E., Bertrand, H., Cirilli, S., Bellieni, G., De Min, A., 2011. Timing and duration of the Central Atlantic magmatic province in the Newark and Culpeper basins, eastern U.S.A. Lithos, 122, 175-188.

37 ACCEPTED MANUSCRIPT

McCune, A. R., Schaeffer, B., 1986. Triassic and Jurassic fishes: Patterns of diversity. In; Padian, K., (Ed.), The beginning of the age of dinosaurs. Cambridge University Press, Cambridge, pp. 171-181. McElwain, J. C., Punyasena, S. W., 2007. Mass extinction events and the plant fossil record. Trends in Ecology and Evolution, 22, 548-557. McElwain, J.C., Beerling, D.J., Woodward, F. I., 1999. Fossil plants and global warming at the Triassic-Jurassic boundary. Science, 285, 1386-1390. McElwain , J. C., Wagner, P. J., Hesselbo, S. P., 2009. Fossil plant relative abundances indicate sudden loss of late Triassic biodiversity in East Greenland. Science, 324, 1554-1556. McElwain, J. C., Popa, M. E., Hesselbo, S. P., Haworth, M., Surlyk, F., 2007. Macroecological responses of terrestrial vegetation to climatic and atmospheric change across the Triassic/Jurassic boundary in East Greenland. Paleobiology, 33, 547-573. McGhee, G. R., Jr., Sheehan, P. M., Bottjer, D. J., Droser, M. L., 2004. Ecological ranking of Phanerozoic biodiversity crises: Ecological and taxonomic severities are decoupled. Palaeogeography, Palaeoclimatology, Palaeoecology, 211, 289-297. McGhee, G. R., Jr., Clapham, M. E., Sheehan, P. M., Bottjer, D. J., Droser, M. L., 2013. A new ecological-severity ranking of major Phanerozoic biodiversity crises. Palaeogeography, Palaeoclimatology, Palaeoecology, 370, 260-270. McHone, J. G., Puffer, J. H., 1996. Hettangian flood basalts across the Pangaean rift. Connecticut State Geological and Natural History Survey NaturalMANUSCRIPT Resources Center Miscellaneous Report, 1, 29. Milner, A. R., 1993. Amphibian-grade Tetrapoda. In: Benton, M. J., (Ed.), The fossil record 2. Chapman and Hall, London, pp. 665-679. Milner, A. R., 1994. Late Triassic and Jurassic amphibians: Fossil record and phylogeny. In: Fraser, N. C., Sues, H-D., (Eds.), In the Shadow of the Dinosaurs. Cambridge University Press, Cambridge, pp. 5-22. Milner, A. R. C., Kirkland, J. I., Birthisel, T. A., 2006. The geographic distribution and biostratigraphy of Late Triassic-Early Jurassic freshwater fish faunas of the western United States. New Mexico Museum of Natural History and Science Bulletin, 37, 522-529. Nesbitt, S. J., 2011. The early evolution of archosaurs: Relationships and the origin of major clades. Bulletin of the American Museum of Natural History, 352, 1-292. Nesbitt, S. J., Brusatte,ACCEPTED S. L., Desojo, J. B., Liparini, A., De Franca, M. A. G., Weinbaum, J. C., Gower, D. J., 2013. Rauisuchia. In: Nesbitt, S. J. Desojo, J. B., Irmis, R. B., (Eds.), Anatomy, phylogeny and palaeobiology of early archosaurs and their kin. Geological Society, London, Special Publications, 379, 241-274.

38 ACCEPTED MANUSCRIPT

Newham, E., Benson, R., Upchurch, P., Goswani, A., 2014. Mesozoic mammaliaform diversity: The effect of sampling corrections on reconstructions of evolutionary dynamics. Palaeogeography, Palaeoclimatology, Palaeoecology, 412, 32-44. Niedźwiedzki, G., 2011. A Late Triassic dinosaur-dominated ichnofauna from the Tomanová Formation of the Tatra Mountains, central Europe. Acta Palaeontologica Polonica, 56, 291- 300. Niklas, K.J., Tiffney, B.H., Knoll, A.H., 1983. Patterns in vascular land plant diversification: A statistical analysis at the species level. Nature, 303, 614-616. Ogg, J. G., 2012a. Triassic. In: Gradstein, F. M., Ogg, J. G., Schmitz, M. D., Ogg, G. M., (Eds) The geologic timescale 2012. volume 2. Elsevier, Amsterdam, pp. 681-730. Ogg, J. G., 2012b. Jurassic. In: Gradstein, F. M., Ogg, J. G., Schmitz, M. D., Ogg, G. M., (Eds.), The geologic timescale 2012. volume 2. Elsevier, Amsterdam, pp. 731-791. Ogg, J. G., Huang, C., Hinnov, L., 2014. Triassic timescale status: A brief overview. Albertiana, 41, 3-30. Olsen, P. E., Galton, P. M., 1984. A review of the reptile and amphibian assemblages from the Stormberg of South Africa, with special emphasis on the footprints and the age of the Stormberg. Palaeontologica Africana, 25, 87-110. Olsen, P. E., Rainforth, E. C., 2003. The Early Jurassic ornithischian dinosaur ichnogenus Anomoepus. In: LeTourneau, P. M., Olsen, P. E., (Eds.), The great rift valleys of Pangea in eastern North America. volume 2. Sedimentology, Stratigraphy,MANUSCRIPT and Paleontology. Columbia University Press, New York, pp. 314-368.. Olsen, P.E., Sues, H-D., 1986. Correlation of continental Late Triassic and Early Jurassic sediments, and patterns of the Triassic-Jurassic tetrapod transition. In: Padian, K., (Ed.), The beginning of the age of dinosaurs. Cambridge University Press, Cambridge, pp. 321-351. Olsen, P.E., Fowell, S.J., Cornet, B., 1990. The Triassic/Jurassic boundary in continental rocks of eastern North America; a progress report. Geological Society of America Special Paper, 247, 585-593. Olsen, P. E., Kent, D. V., Whiteside, J. H., 2011. Implications of the Newark Supergroup-based astrochronology and geomagnetic polarity time scale (Newark-APTS) for the tempo and mode of the early diversification of the Dinosauria. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 101, 201-229. Olsen, P. E., Schlische,ACCEPTED R. W., Fedosh, M. S., 1996. 580 ky duration of the Early Jurassic flood basalt event in eastern North America estimated using Milankovitch cyclostratigraphy. Museum of Northern Arizona Bulletin, 60, 11-22. Olsen, P.E., Shubin, N. H., Anders, M. H., 1987. New Early Jurassic tetrapod assemblages constrain Triassic-Jurassic tetrapod extinction event. Science, 237, 1025-1029.

39 ACCEPTED MANUSCRIPT

Olsen, P.E., Smith, J.B., McDonald, N.G., 1998. Type material of the type species of the classic theropod footprint genera Eubrontes, Anchisauripus, and Grallator (Early Jurassic, Hartford and Deerfield basins, Connecticut and Massachusetts, U. S. A.). Journal of Vertebrate Paleontology, 18, 586-601. Olsen, P. E., Reid, J. C., Taylor, K. B., Whiteside, J. H., Kent, D. V., 2015. Revised stratigraphy of Late Triassic age strata of the Dan River basin (Virginia and North Carolina, USA) based on drill core and outcrop data. Southeastern Geology, 51, 1-31. Olsen, P.E., Kent, D.V., Sues, H.D., Koeberl, C., Huber, H., Montanari, A., Rainforth, E.C., Powell, S.J., Szajna, M.J., Hartline, B.W., 2002a. Ascent of dinosaurs linked to an iridium anomaly at the Triassic-Jurassic boundary. Science, 296, 1305-1307. Olsen, P.E., Koeberl, C., Huber, H., Montanari, A., Fowell, S.J., Et-Touhani, M., Kent, D.V., 2002b. The continental Triassic-Jurassic boundary in central Pangea: Recent progress and preliminary report of an Ir anomaly. Geological Society of America Special Paper, 356, 505- 522. Onoue, T., Sato, H., Nakamura, T., Noguchi, T., Hidaka, Y., Shirai, N., Ebihara, M., Osawa, T., Hatsukawa, Y., Toh, Y., Koizumi, M., Harada, H., Orchard, M. J., Nedachi, M., 2012. Deep- sea record of impact apparently unrelated to mass extinction in the Late Triassic. Proceedings of the National Academy of Science, 109, 19134-19139. Orbell, G., 1973. Palynology of the British Rhaeto-Liassic.MANUSCRIPT Bulletin of the Geological Society of Great Britain, 44, 1-44. Orchard, M. J., 2010. Triassic conodonts and their role in stage boundary definition. In: Lucas, S. G., (Ed.), The Triassic timescale. Geological Society, London, Special Publication, 334, 139- 161. Orchard, M. J., 2013. Five new genera of conodonts from the Carnian-Norian boundary beds of Black Bear Ridge, northeast British Columbia, Canada. New Mexico Museum of Natural History and Science Bulletin, 61, 445-457. Orchard, M. J., 2014.Conodonts from the Carnian-Norian boundary (Upper Triassic) of Black Bear Ridge, northeastern British Columbia, Canada. New Mexico Museum of Natural History and Science Bulletin, 64, 1-139. Pedersen, K.R., Lund, J. J., 1980. Palynology of the plant-bearing Rhaetian to Hettangian Kap Stewart Formation,ACCEPTED Scoresby Sund, East Greenland. Review of Palaeobotany and Palynology, 31, 1- 69. Pieńkowski, G., Niedźwiedzki, G., Branski, P., 2014. Climatic reversals related to the Central Atlantic magmatic province caued the end-Triassic biotic crisis—Evidence from continental strata in Poland. Geological Society of America Special Paper, 505, 263-286.

40 ACCEPTED MANUSCRIPT

Pieńkowski, G., Niedźwiedzki, G., Waksmundzka, M., 2011. Sedimentological, palynological and geochemical studies of the terrestrial Triassic-Jurassic boundary in northwestern Poland. Geological Magazine, 149, 308-332. Pott, C., McLoughlin, S., 2009. Bennettitalean foliage in the Rhaetian-Bajocian (latest Triassic- Middle Jurassic) floras of Scania, southern Sweden. Review of Palaeobotany and Palynology, 158, 117-166. Rainforth, E. C., 2003. Revision and re-evaluation of the Early Jurassic dinosaurian ichnogenus Otozoum. Palaeontology, 46, 803-838. Ramezani, J., Bowring, S. A., Pringle, M., Winslow III, F. D., Rasbury, E. T., 2005. The Manicouagan impact melt rock: A proposed standard for intercalibration of U-Pb and 40Ar/39/Ar isotopic systems. 15th V. M. Goldschmidt Conference Abstract Volume, A321. Rigo, M., Preto, N., Roghi, G., Tateo, F., Mietto, P., 2007. A rise in the carbonate compensation depth of western Tethys in the Carnian (Late Triassic): Deep-water evidence for the Carnian pluvial event. Palaeogeography, Palaeoclimatology, Palaeoecology, 246, 188-205. Ruckwied, K., Götz, A. E., Pálfy, J., Török, Á., 2008. Palynology of a terrestrial coal-bearing series across the Triassic/Jurassic boundary (Mecsek Mts, Hungary). Central European Geology, 51, 1-15. Ruhl, M., Veld, H., Kuerschner, W. M., 2010. Sedimentary organic matter characterization of the Triassic-Jurassic boundary GSSP at Kuhjoch (Austria).MANUSCRIPT Earth and Planetary Science Letters, 292, 17-26. Schäfer, P., Fois, E., 1987. Systematics and evolution of Triassic Bryozoa. Geologica et Palaeontologica, 21, 173-225. Schaller, E. M., Wright, J. D., Kent, D. V., Olsen, P. E., 2012. Rapid emplacement of the Central

Atlantic Magmatic Province as net sink for CO2. Earth and Planetary Science Letters, 323- 324, 27-39. Schoch, R. R., Milner, A. R., 2000. Stereospondyli. Encyclopedia of Paleoherpetology, 3B, 1-203. Schoene, B., Guex, J., Bartolini, A., Schaltegger, U., Blackburn, T. J., 2010, Correlating the end- Triassic mass extinction and flood basalt volcanism at the 100 ka level. Geology, 38, 387- 390. Schootbrugge, B. van de, Quan, T., Lindström, S., Püttmann, W., Heunisch, C., Pross, J., Fiebig, J., Petschick,ACCEPTED R., Röhling, H-G., Richoz, S., Rosenthal, Y., Falkowski, P. G., 2009. Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism. Nature Geoscience, 2, 589-594. Schuurman, W. M. L., 1979. Aspects of Late Triassic palynology. 3. Palynology of latest Triassic and earliest Jurassic deposits of the northern limestone Alps in Austria and southern Germany,

41 ACCEPTED MANUSCRIPT

with special reference to a palynological characterization of the Rhaetian stage in Europe. Review of Palaeobotany and Palynology, 27, 53-75. Sepkoski, J. J., Jr., 1982. Mass extinctions in the Phanerozoic oceans: A review. Geological Society of America Special Paper, 190, 283-289. Sha, J., Olsen, P. E., Pan, Y., Xu, D., Wang, Y., Zhang, X., Yao, X., Vajda, V., 2015. Triassic-Jurassic climate in continental high-latitude Asia was dominated by obliquity-paced variations (Junggar Basin, Ürümqi, China). Proceedings of the National Academy of Sciences, 112, 3624-3629. Sha, J., Vajda, V., Pan, Y., Larsson, L., Yao, X., Zhang, X., Wang, Y., Cheng, X., Jiang, B., Deng, S., Chen, S., Peng, B., 2011. Stratigraphy of the Triassic-Jurassic boundary successions of the southern margin of the Junggar basin, northwestern China. Acta Geologica Sinica, 85, 421- 436. Shubin, N. H., Olsen, P. E., Sues, H.-D., 1994. Early Jurassic small tetrapods from the McCoy Brook Formation of Nova Scotia, Canada. In: Fraser, N. C., Sues, H-D., (Eds.) In the shadow of the dinosaurs. Cambridge University Press, Cambridge, pp. 242-250. Sigurdsson, H., 1990. Assessment of atmospheric impact of volcanic eruptions. Geological Society of America Special Paper, 247, 99-110. Silvestri, S. M., Szajna, M. J., 1993. Biostratigraphy of vertebrate footprints in the Late Triassic section of the Newark Basin, Pennsylvania: ReassessmentMANUSCRIPT of stratigraphic ranges. New Mexico Museum of Natural History and Science Bulletin, 3, 439-445. Simms, M. J., Ruffell, A. H., 1989. Synchroneity of climatic change and extinctions in the Late Triassic. Geology, 17, 265-268. Simms, M. J., Ruffell, A. H., 1990. Climatic and biotic change in the Late Triassic. Journal Geological Society (London), 147, 321-327. Smith, R. M. H., Marsicano, C. A., Wilson, J. A., 2009. Sedimentology and paleoecology of a diverse Early Jurassic tetrapod tracksite in Lesotho, southern Africa. Palaios, 24, 672-684. Spielmann, J. A., Lucas, S. G., Hunt, A. P., 2013. The first Norian (Revueltian) rhynchosaur: Bull Canyon Formation, New Mexico, U. S. A. New Mexico Museum of Natural History and Science Bulletin, 61, 562-566.

Steinthorsdottir, M., Jeram, A. J., McElwain, J. C., 2011. Extremely elevated Co2 concentrations at the Triassic/JurassicACCEPTED boundary. Palaeogeography, Palaeoclimatology, Palaeoecology, 308, 418- 432. Stocker, M. R., Butler, R. J., 2013. Phytosauria. In: Nesbitt, S. J. Desojo, J. B., Irmis, R. B., (Eds.), Anatomy, phylogeny and palaeobiology of early archosaurs and their kin. Geological Society, London, Special Publications, 379, 91-118.

42 ACCEPTED MANUSCRIPT

Sues, H-D., Olsen, P. E., 2015. Stratigraphic and temporal context and faunal diversity of Permian- Jurassic continental tetrapod assemblages from the Fundy rift basin, eastern Canada. Atlantic Geology, 51, 139-205. Szajna, M. J., Silvestri, S. M., 1996. A new occurrence of the ichnogenus Brachychirotherium: Implications for the Triassic-Jurassic mass extinction event. Museum of Northern Arizona Bulletin, 60, 275-283. Szulc, J., Racki, G., Środoń, J., Lucas, S. G., 2015. Norian age of the Lipie Śląskie vertebrate fauna explains its alleged oddity. Acta Palaeontologica Polonica, in press

Tanner, L. H., Hubert, J. F., Coffey, B. P., McInerney, D. P., 2001. Stability of atmospheric CO2 levels across the Triassic/Jurassic boundary. Nature, 411, 675-677. Tanner, L. H., Lucas, S. G., Chapman, M. G., 2004. Assessing the record and causes of Late Triassic extinctions. Earth-Science Reviews, 65, 103-139.

Tanner, L.H., Smith, D.L., Allan, A., 2007. Stomatal response of swordfern to volcanogenic CO2 and

SO2 from Kilauea volcano, Hawaii. Geophysical Research Letters, 34, L15807, doi:10.1029/2007GL030320. Thulborn, T., Turner, S., 2003. The last dicynodont: An Australian Cretaceous relict. Proceedings Royal Society London B, 270, 985-993. Traverse, A., 1988. Plant evolution dances to a different beat. Historical Biology, 1, 277-301. Valais, S de., 2009. Ichnotaxonomic revision of AmeghinichnusMANUSCRIPT, a mammalian ichnogenus from the Middle Jurassic La Matilde Formation, Santa Cruz Province, Argentina. Zootaxa, 2203, 1-21. Visscher, H., Van Houte, M., Brugman, W. A., Poort, R. J., 1994. Rejection of a Carnian (late Triassic) “pluvial event” in Europe. Review of Palaeobotany and Palynology, 83, 217-226. Weems, R. E., 1992. The “terminal Triassic catastrophic extinction event” in perspective: A review of Carboniferous through Early Jurassic terrestrial vertebrate extinction patterns. Palaeogeography, Palaeoclimatology, Palaeoecology, 94, 1-29. Weems, R. E., Lucas, S. G., 2015. A revision of the Norian conchostracan zonation in North America and its implications for Late Triassic North American tectonic history. New Mexico Museum of Natural History and Science Bulletin, 67, 303-317. Whiteside, J. H., Olsen, P. E., Kent, D. V., Fowell, S. J., Et-Touhami, M., 2007. Synchrony between the Central Atlantic magmatic province and the Triassic-Jurassic mass-extinction event? Palaeogeography,ACCEPTED Palaeoclimatology, Palaeoecology, 244, 345-367. Whiteside, J. H., Olsen, P. E., Eglinton, T., Brookfield, M. E., Sambrotto, R. N., 2010. Compound- specific carbon isotopes from Earth's largest flood basalt eruptions directly linked to the end- Triassic mass extinction. Proceedings National Academy of Science USA, 107, 6721-6725. Wotzlaw, J-F., Guex, J., Bartolini, A., Gallet, Y., Krystyn, L., McRoberts, C. A., Taylor, D., Schoene, B., Schaltegger, U., 2014. Towards accurate numerical calibration of the Late Triassic: High-

43 ACCEPTED MANUSCRIPT

precision U-Pb geochronology constraints on the duration of the Rhaetian. Geology, 42, 571- 574. Yapp, C.J., Poths, H., 1996. Carbon isotopes in continental weathering environments and variations in

ancient atmospheric CO2 pressure. Earth and Planetary Science Letters, 137, 71-82.

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