End-Triassic Nonmarine Biotic Events

journal of palaeogeography 4 (2015) 331e348

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End-Triassic nonmarine biotic events

Spencer G. Lucas a,*, Lawrence H. Tanner b a New Mexico Museum of Natural History, 1801 Mountain Road NW, Albuquerque, NM 87104-1375, USA b Department of Biological Sciences, Le Moyne College, 1419 Salt Springs Road, Syracuse, NY 13214, USA article info abstract

Article history: The Late Triassic was a prolonged interval of elevated extinction rates and low origination Received 1 July 2015 rates that manifested themselves in a series of extinctions during Carnian, Norian and Accepted 15 August 2015 Rhaetian time. Most of these extinctions took place in the marine realm, particularly Available online 21 September 2015 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 Keywords: focused on tetrapod vertebrates (amphibians and reptiles), though some workers advocate TriassiceJurassic boundary a sudden end-Triassic (TJB) extinction of land plants. Nevertheless, an extensive literature Mass extinction does not identify a major extinction of land plants at the TJB, and a comprehensive review Land plants of palynological records concluded that TJB vegetation changes were non-uniform East Greenland (different changes in different places), not synchronous and not indicative of a mass Tetrapods extinction of land plants. Claims of a substantial perturbation of plant ecology and di- Newark Supergroup versity at the TJB in East Greenland are indicative of a local change in the paleoflora largely CAMP volcanism 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 events are relatively low on the global scale. Biotic turnover at the end of the Triassic was likely driven by the CAMP (Central Atlantic Magmatic Province) 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. © 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of China University of Petroleum (Beijing). This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

* Corresponding author. E-mail address: [email protected] (S.G. Lucas). Peer review under responsibility of China University of Petroleum (Beijing). http://dx.doi.org/10.1016/j.jop.2015.08.010 2095-3836/© 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of China University of Petroleum (Beijing). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 332 journal of palaeogeography 4 (2015) 331e348

1. Introduction

The biodiversity crisis at the end of the Triassic (Tri- assiceJurassic 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 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 Triassic¡Early Jurassic timescale

We use the standard global chronostratigraphic timescale for the Late TriassiceEarly 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)(Fig. 1). The base of one of the three Late Triassic stages (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., Fig. 1 e Correlation of the Late Triassic¡earliest Jurassic 2010; Krystyn et al., 2007; Lucas, 2010a, 2013b; Orchard, 2010, standard global chronostratigraphic scale (sgcs) to tetrapod 2013, 2014). biochronology based on land-vertebrate faunachrons (lvfs). The favored definition of the Rhaetian base has as its pri- See text for sources. mary signal the LO (lowest occurrence) of the conodont Mis- ikella 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, 2012) and Lucas and Tanner (2007b) (Fig. 1). Many Late Giordano et al. (2010) concluded that the LO of Misikella post- Triassic megafossil plant localities can be directly related to hernsteini is actually younger at Steinbergkogel than it is in the this tetrapod-based biochronology (e.g., Lucas, 2013a). Paly- section they studied in the Lagronegro basin in southern Italy, nostratigraphic correlations in much of this interval are dis- so the Italian section may become the GSSP location. The GSSP cussed in a comprehensive way by Cirilli (2010) and Ku¨ rschner defined for the TJB (base of Jurassic System ¼ base of Het- and Herngreen (2010). Conchostracan biostratigraphy for the tangian Stage) is correlated by the lowest occurrence of the Late TriassicEarly Jurassic also can be tied directly to the ammonoid Psiloceras spelae (Hillebrandt et al., 2013). The best tetrapod biostratigraphy and biochronology (Kozur and numerical calibration places this boundary close to 201.4 Ma Weems, 2005, 2007, 2010; Lucas et al., 2011, 2012; Weems (Schoene et al., 2010, Fig. 1). and Lucas, 2015). Correlation of nonmarine and marine biochronology in the An extremely important point is that correlation of Late Late TriassicEarly Jurassic remains imprecise. Here, we pri- Triassic nonmarine biochronology to the standard global marily rely on the correlations based on tetrapod biostratig- chronostratigraphic scale is achieved primarily by correlation raphy and biochronology (land-vertebrate faunachrons) to the Germanic basin section, where marine intercalations advocated by Lucas (1998, 2008, 2010b), Lucas et al. (2007a, and other data provide a reasonably precise cross-correlation journal of palaeogeography 4 (2015) 331e348 333

to the marine Upper Triassic sections in Austria and Italy an obviously Late Triassic tetrapod assemblage (with phyto- (Kozur and Bachman, 2005, 2008; Kozur and Weems, 2010; saurs, aetosaurs, etc) of likely Norian age in the lower Dhar- Lucas, 2010a, 2010b). For the Lower Jurassic, non- maram Formation, overlain hundreds of meters higher by the marineemarine correlation tiepoints exist (e. g., Lucas, 2008), clearly Jurassic (likely Sinemurian), dinosaur-dominated but are constrained in much less detail than is the Upper tetrapod assemblage of the Kota Formation. All that in- Triassic record. tervenes are two undescribed tetrapod taxada spheno- Magnetostratigraphy also provides some service to corre- dontian and a plateosaurid dinosaurdfrom the upper lation of nonmarine and marine strata across the TJB, but not Dharmaram Formation. Lucas and Huber (2003) suggested the precision always needed. The Rhaetian-early Hettangian these fossils are likely Late Triassic in age, but Bandyopadhyay interval is a time of dominantly normal polarity, and each and Sengupta (2006) assigned them a Hettangian age. They section studied reveals from two to four short intervals of then claimed the Gondwana basin record shows a substantial reversed polarity in the dominantly normal Rhaetian- turnover in tetrapods at the TJB, even though the two as- Hettangian multichron (e.g., Hounslow and Muttoni, 2010; semblages in India that are comparable across that boundary Hounslow et al., 2004; Lucas and Tanner, 2007b; Lucas et al., are likely Norian and Sinemurian in age, and thus separated 2011; Marzoli et al., 2004). Correlation of these short re- by at least 6 million years, invalidating their conclusion. versals to each other is not straightforward and forces a reli- Another example comes from the work of Pienkowski et al. ance on biostratigraphic or chemostratigraphic inferences to (2011, 2014) in Poland, where late Norian tetrapod body fossils provide precise correlations within the Rhaetian-Hettangian are compared to Hettangian(?) footprint assemblages and multichron (for example, see Lucas and Tanner, 2007b, show a change from diverse, dicynodont- and archosaur- Figure 7). dominated faunas to dinosaur-dominated footprint faunas. Incorrect placement of the TJB boundary in the Newark Dinosaur-dominated footprint faunas, however, are also Supergroup long confounded nonmarineemarine correlations known from the Late Triassic (e.g., Lucas, 2007), so the com- and gave the impression of a significant extinction of plants parison of the Polish Norian bone and Hettangian(?) footprint and tetrapods at the TJB (see discussion below). However, well records does not necessarily reflect biotic turnover across the supported and now well accepted correlation of the TJB in the TJB. 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 strati- 3. TJB terrestrial record graphically to a level well removed from any evidence of a sudden biotic turnover. It is fair to say that only seven places on Earth have a record of Correlation of nonmarine strata to the now defined TJB in non-marine TJB fossil plants and tetrapods of sufficient marine strata is achieved by some workers using either extent, diversity and stratigraphic density to be relevant to palynostratigraphy or carbon isotope stratigraphy. However, evaluating a TJB extinction: (1) Chinle-Glen Canyon Group palynostratigraphy does not unambiguously identify the succession of the American Southwest; (2) Newark Super- boundary in many sections (Bonis and Ku¨ rschner, 2012; Bonis group strata of the eastern seaboard of North America from et al., 2009; Pienkowski et al., 2011). And, many nonmarine Nova Scotia to the Carolinas, and including rift basin deposits carbon isotope records rely on too few data points to of Morocco in North Africa; (3) Jameson Land in eastern convincingly identify the carbon-isotope excursions recog- Greenland; (4) European records inside and outside of the nized in marine sections across the TJB or produce records Germanic basin, particularly in Germany, the United Kingdom with such high noise levels as to defy correlation (e.g., and Italy; (6) northwestern Argentina; and (7) the Karoo basin McElwain et al., 1999). Recent examples of such problematic of South Africa (Fig. 2). carbon-isotope-based correlations of the TJB in nonmarine Today, and (based on actualism) during the TJB interval, strata include Gomez et al. (2007) in Spain, Whiteside et al. much terrestrial diversity is accounted for by monerans and (2010) in the USA, Pienkowski et al. (2011, 2014) in Poland arthropods. Yet, the monerans have virtually no fossil record, and Hesselbo et al.'s (2002) carbon-isotope curve in East and the record of arthropods across the TJB is essentially Greenland, discussed below. nonexistent for many groups. Arthropod groups that have Nevertheless, such considerations do not deter some relatively good TJB fossil records, such as ostracods and con- workers from precise placement of the TJB in nonmarine chostracans, show no significant extinction at the TJB (e.g., sections where few if any data exist to support precise Kozur and Weems, 2010). Insects also have a fossil record that placement. Thus, for example, Sha et al. (2011, 2015) recently shows no evidence of a diversity crash across the TJB placed the TJB in nonmarine strata of the Junggur Basin in (Grimaldi and Engel, 2005; Labandeira and Sepkoski, 1993). northwestern China using palynomorphs and nonmarine bi- Indeed, Grimaldi and Engel (2005, p. 73) concluded, “there valves that cannot be unambiguously correlated with preci- seems to have been little differentiation between insect sion to any other TJB section. faunas of the Late Triassic and Early Jurassic.” More problematic are nonmarine sections where the TJB Plant diversity across the TJB is based on a much better can only be approximated, and that approximation separates fossil record, both in the form of megafossil plants and their very different nonmarine fossil assemblages that differ in age microfossil “proxies,” the palynomorphs (sporomorphs). The by many millions of years. A good example of this is provided record of terrestrial fossil vertebrates across the TJB is com- by the study of the tetrapod record in the Gondwana basins of parable in quality to the plant record, and it shows no evident India by Bandyopadhyay and Sengupta (2006). This record has extinction of freshwater fishes (McCune and Schaeffer, 1986; 334 journal of palaeogeography 4 (2015) 331e348

Fig. 2 e Principal localities that are referred to in the text where the nonmarine Triassic¡Jurassic boundary interval has a dense fossil record: A ¼ Argentina, C ¼ Chinle basin, American Southwest, G ¼ Germanic basin, J ¼ Jameson Land, East Greenland, K ¼ Karoo basin, South Africa and N ¼ Newark Supergroup basins.

Milner et al., 2006). Supposed TJB tetrapod extinctions focus (2009: 117), as anything more than a “moderate taxonomic on three principal groups: temnospondyl amphibians, some turnover,” and it is a palaeogeographically local event. archosaur taxa and some synapsid taxa. These records have Contrary to prevailing thought, McElwain and collabora- been evaluated using both body fossils (bones and teeth) and tors (Bacon et al., 2013; Belcher et al., 2010; Mander et al., 2010, trace fossils (footprints). 2012; McElwain and Punyasena, 2007; McElwain et al., 1999, 2007, 2009) claim significant changes in the megaflora at the TJB in East Greenland (Fig. 3). According to these workers, these encompass a sudden change from high diversity Late 4. Land plants Triassic plant communities to lower diversity and less taxo- nomically even Early Jurassic communities. This is the only 4.1. Overview location where a case has been made for a major turnover in the megaflora at the TJB, but we question whether the data An extensive literature does not identify a major extinction of support recognition of a megafloral crisis in East Greenland of land plants at the TJB (e.g., Ash, 1986; Brugman, 1983; Burgoyne more than local palaeogeographic significance. et al., 2005; Cascales-Minana~ and Cleal, 2011; Cleal, 1993a, 1993b; Edwards, 1993; Fisher and Dunay, 1981; Galli et al., 4.2. Plant extinctions in east Greenland 2005; Hallam, 2002; Kelber, 1998; Knoll, 1984; Kuerschner et al., 2007; Lucas and Tanner, 2004, 2007b, 2008; McElwain The Astartekløft section of the Primulaev Formation of the and Punyasena, 2007; Niklas et al., 1983; Orbell, 1973; Kap Stewart Group in Jameson Land, East Greenland (Fig. 3) Pedersen and Lund, 1980; Ruckwied et al., 2008; Schuurman, apparently encompasses the TJB and records the transition 1979; Tanner et al., 2004; Traverse, 1988). Most reviews iden- from the Lepidopteris floral zone to the Thaumatopteris floral tify only the extinction of peltasperms, a clade of seed ferns, at zone, with few species shared by both zones (Harris, 1937). the TJB. Global compilations at the species and family levels The former is characterized by the presence of paly- show no substantial plant extinction at the TJB (Cleal, 1993a, nomorphs, including Rhaetipollis, while the latter contains 1993b; Edwards, 1993; Knoll, 1984; Niklas et al., 1983). A Heliosporites (Pedersen and Lund, 1980), and although extinc- recent analysis by Cascales-Minana~ and Cleal (2011:76e77) tion of some species across the transition between the two concluded that “the changes observed in the plant fossil record zones is evident, many species occur in both zones. Thus, in the Late Triassic Series are mainly reflecting an ecological Harris (1937: 76) emphasized that “real mixing” of the two reorganization of the terrestrial habitats weeding-out some of floral zones occurs over a 10 m interval (Fig. 3), and “this is the families of less adaptable plants that had filled the newly real mixing … .the two sets of plants will be seen on the same available niches during Triassic times, rather than a global bedding plane and they continue to be found together from ecological crisis on the scale of that seen at the end of Permian top to bottom, of one of these beds … .” Therefore, the data times.” and analyses of Harris (1937) and Pedersen and Lund (1980) Some data do reveal local turnover of paleofloras across the did not identify an abrupt change in the land plants across TJB. A good example is a study of Swedish benettitaleans that the TJB in Jameson Land. Furthermore, what species turnover documented restriction of two species to the Rhaetian fol- looks abrupt in this section was attributed by Harris (1937) lowed by five species restricted to the Hettangian. However, and Pedersen and Lund (1980) to species range truncations this is not considered by its authors, Pott and McLoughlin at a depositional hiatus, an unconformity also recognized in journal of palaeogeography 4 (2015) 331e348 335

Fig. 3 e Measured section of TriassiceJurassic 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).

the Astartekløft section by Dam and Surlyk (1993) and (based on megafossil plants but not reﬂected in the paly- Hesselbo et al. (2002) (Fig. 3). nomorph record); (2) a decrease in the relative abundance of In contrast, in this section McElwain and collaborators common plant species at the TJB; (3) a change in leaf physi- claim: (1) a sudden, 85% drop in species diversity at the TJB ognomy to larger and rounder leaves; (4) an increase in 336 journal of palaeogeography 4 (2015) 331e348

charcoal indicative of wildfire at the TJB; and (5) an increase in lithofacies, and this raises the possibility that at least some of chemical damage to sporomorphs at the TJB. They see all but the apparent floral change inferred by McElwain and collab- possibly the last of these as indicative of a “super greenhouse” orators is due to the change in the depositional system (lith- caused by CAMP eruptions. ofacies). Assuming the TJB is present in this section near the We question, though, the validity of the placement of the 47 m level, the megafossil plant assemblages across the TJB TJB in the Astartekløft section. McElwain and collaborators are clearly not “isotaphonomic” (as claimed by McElwain place it at about the 47 m level of this section, basing that et al., 2007), so they are not strictly comparable to each other placement on the carbon isotope record published by in terms of composition, diversity and relative abundance. Hesselbo et al. (2002) (Fig. 3). This record shows an apparent, According to McElwain and collaborators, a substantial but modest (~2%o), negative excursion beginning at about the perturbation of plant ecology and diversity is preserved at the 45 m level. We note that this “excursion” coincides with an TJB in East Greenland. We suggest that the data they present unconformity of unknown duration. Hence, the relationship are indicative of a palaeogeographically local change in the of the isotopic trend above this hiatus to the missing, under- paleoflora largely driven by lithofacies changes resulting in lying strata is undetermined. Moreover, the general isotopic changing taphonomic filters. No catastrophic land plant trend for this section bears little similarity to the published extinction is documented and, at most, the floral turnover in isotope stratigraphy for sections of putative identical age. East Greenland is nothing more than a palaeogeographically Nevertheless, Hesselbo et al. (2002) assumed that the base local event, as no similar, coeval event is documented else- of the excursion represents the “initial isotope excursion” and where (Hallam and Wignall, 1997; Lucas and Tanner, 2008; that the remainder records the “main isotope excursion” seen Tanner et al., 2004). Furthermore, whatever happened to the in marine sections that cross the TJB (e.g., Ruhl et al., 2010). megaflora in East Greenland, it happened very late in the Therefore, the intervening section with a more positive iso- Triassic, not at the TJB. topic trend (spanning 4 m at St. Audrie's Bay in England) is conveniently missing, so we regard Hesselbo et al.'s (2002) 4.3. Plant microfossils correlation as tenuous at best. Furthermore, if the initial negative excursion at the ~45 m level in the Astartekløft sec- Like the megafossil plant record, the palynological record tion is the well documented (in marine sections) negative provides no evidence for a mass extinction of land plants at excursion in carbon then it is not the TJB, but instead a point in the TJB (Bonis and Ku¨ rschner, 2012). Decades ago, Fisher and the Rhaetian (e.g., Hillebrandt et al., 2013; Lucas et al., 2007b; Dunay (1981) demonstrated that a significant proportion of Mander et al., 2013; Ruhl et al., 2010). Thus, all the events the Rhaetipollis germanicus assemblage that defines the Rhae- McElwain and collaborators associate with the TJB actually tian in Europe (e. g., Orbell, 1973; Schuurman, 1979) persists in preceded it. lowermost Jurassic strata, and this remains the case (e.g., The chemostratigraphic correlation proposed by Hesselbo Bonis and Ku¨ rschner, 2012; Bonis et al., 2009; Cirilli, 2010; et al. (2002) relies on the presence of an unconformity at Ku¨ rschner and Herngreen, 2010). Brugman (1983) and 47 m in the Astartekløft section. Questions should be raised Traverse (1988) thus concluded that floral turnover across the about the nature of this unconformity and the temporal TJB was gradual, not abrupt. Kelber (1998) described the magnitude of the hiatus it represents, as well as the associated megaflora and palynoflora for Central Europe in a single unit substantial change in lithofacies (Fig. 3). Indeed, we note that he termed “Rhaeto-Liassic”, and concluded there was no most of the megafossil plant assemblages below that level are serious disruption or decline in plant diversity across the TJB. from mudrock-dominated intervals, whereas almost all of More recently, Kuerschner et al. (2007) and Bonis et al. (2009) those above that level are from sandstone (Fig. 3). According to documented the transitional nature of the change in paly- McElwain et al. (2007, p. 551), the mudrock likely represents nomorphs across the TJB in the Northern Calcareous Alps of floodplain deposits of mainly autochthonous plants, whereas Austria (also see Hillebrandt et al., 2013), and the paly- the sandstones represent channel and splay deposits that also nomorph record in East Greenland also does not document an include allochthonous plants. However, in evident contra- abrupt TJB extinction (Mander et al., 2010, 2013). diction to parts of their text and measured stratigraphic sec- Nevertheless, profound palynomorph extinction at the TJB tion, McElwain et al. (2007, table 1) identify all the plant was long identified in the Newark Supergroup record in localities up through their bed 5 as coming from “sheet splay” eastern North America by Olsen and collaborators (Cornet, deposits, the plants from bed 6 as from a coal swamp (though 1977; Cornet and Olsen, 1985; Fowell and Olsen, 1993; Olsen no coal is present in the section at Astartekløft) and their plant and Sues, 1986; Olsen et al., 1990, 2002a, 2002b). Their work beds 7 and 8 as coming from abandoned channels. In the identified the TJB in the Newark section by a decrease in di- absence of more data (e.g., detailed lithologic descriptions of versity of the plant microfossil assemblage, defined by the loss the plant-bearing strata) and an actual sedimentological of palynomorphs considered typical of the Late Triassic, fol- analysis of the plant-bearing beds, we are not able to resolve lowed by dominance of the palynoflora by several species of these evident contradictions in the study of McElwain et al. the genus “Corollina” (¼ Classopollis), especially C. meyeriana (2007). (Cornet and Olsen, 1985; Fowell and Olsen, 1993; Fowell and Instead, it seems evident that the section at Astartekløft Traverse, 1995; Fowell et al., 1994; Olsen et al., 1990). They embodies a major lithofacies change at an unconformity, from thus placed the TJB in the Newark section at the base of the a mudstone- and sheet-sandstone-dominated depositional Classopollis meyeriana palynofloral zone (Fig. 4). These workers system to a thick, channel-sandstone-dominated system attached considerable importance to a peak abundance of (Fig. 3). On face value, it preserves two taphofloras in different trilete spores at this level, which they termed a “fern spike” journal of palaeogeography 4 (2015) 331e348 337

Fig. 4 e Biostratigraphic correlation of the Newark Supergroup section from the Late Triassic through the Triassic¡Jurassic boundary. Note unconformities indicated by missing conchostracan zones. Modiﬁed from Kozur and Weems (2010), Lucas et al. (2012) and Weems and Lucas (2015).

(Cornet and Olsen, 1985; Fowell and Olsen, 1993; Fowell et al., Bonis and Ku¨ rschner (2012) provided a comprehensive re- 1994; Whiteside et al., 2007). Although not present in all of the view of TJB palynological records to conclude that they indi- Newark basins (e.g., Cirilli et al., 2009), an increase in trilete cate vegetation changes that are non-uniform (different spores has been noted in some European sections, where the changes in different places), not synchronous and not indic- acme zone is referred to as the Triletes Beds (Kuerschner et al., ative of a mass extinction of land plants. They attributed these 2007; Ruhl et al., 2010; van de Schootbrugge et al., 2009). As changes to climate change driven by CAMP volcanism that noted by van de Schootbrugge et al. (2009), however, occur- produced a warmer climate and stronger monsoonal flow rences of a fern-dominated flora at the level of this apparent across Pangea, which developed drier interiors and wetter palynological turnover are limited strictly to the Northern coastal regions. As they well put it, “… instead of a major and Hemisphere. globally consistent palynofloral extinction event, the Tr/J This palynofloral change has been referred to as the “T-J boundary is characterized by climate-induced quantitative palynofloral turnover” (Whiteside et al., 2007) or the “Passaic changes in the sporomorph assemblages that vary regionally palynofloral event” (Lucas and Tanner, 2007b). But, as Kozur in magnitude and composition” (Bonis and Ku¨ rschner, 2012: and Weems (2005: 33) well observed, “there are no age- 256). In summary, there is no evidence of a global mass diagnostic sporomorphs or other fossils to prove that this extinction of land plants at the TJB. extinction event occurred at the TriassicJurassic boundary.” Indeed, Kuerschner et al. (2007) concluded that the Newark palynological event most likely represents an older, poten- 5. Tetrapods tially early Rhaetian event, a conclusion shared by Kozur and Weems (2005, 2007, 2010) and by Lucas and Tanner (2007b). 5.1. Overview Thus, the palynological turnover in the Newark preceded the TJB (Fig. 4) and was a palaeogeographically regional event, not The idea of a substantial nonmarine tetrapod extinction at the a global mass extinction. TJB began with Colbert (1949, 1958), and has been more 338 journal of palaeogeography 4 (2015) 331e348

recently advocated by Olsen et al. (1987, 1990, 2002a, 2002b). significance or cosmopolitan taxa with long stratigraphic Nevertheless, Weems (1992), Benton (1994), Lucas (1994), ranges. As Lucas and Hunt (1994: 340) noted, “a single age Tanner et al. (2004) and Lucas and Tanner (2004, 2007b, 2008) should not necessarily be assigned to the fossils from one rejected this conclusion. fissure and....individual fossils from the fissures may range in Colbert (1958) concluded that the temnospondyl amphib- age from middle Carnian to Sinemurian.” We thus regard as ians, a significant component of many late Paleozoic and Ear- problematic the precise age of many of the Triassic tetrapod lyMiddle Triassic tetrapod assemblages, underwent fossils from the British fissure fills. complete extinction at the TJB. However, these temnospondyls Phytosaur fossils are known from Rhaetian-age strata in are only a minor component of Late Triassic tetrapod assem- the Newark section, the Glen Canyon Group and the Germanic blages, being of low diversity and relatively small numbers in basin (e.g., Lucas and Tanner, 2007a; Olsen et al., 2002a, 2002b; most stratigraphic units (e.g., Hunt, 1993; Long and Murry, Stocker and Butler, 2013). A Lower Jurassic phytosaur record 1995). Moreover, current data demonstrate the disappearance has been documented by Maisch and Kapitzke (2010). This is of most of the temnospondylsecapitosaurids, metoposaurids an unabraded snout fragment found in the lowermost Jurassic and latiscopidseat or just before the NorianeRhaetian pre-planorbis beds (Neophyllites zone) at Watchet in England. boundary, and only one family extinct at the end of the Triassic Stocker and Butler (2013) expressed skepticism about the (plagiosaurids) (Milner, 1993, 1994; Schoch and Milner, 2000). stratigraphic provenance of this record, and it may be a Late Triassic temnospondyl extinctions thus largely preceded reworked fossil, a possibility difficult to test. We accept that it the TJB. documents phytosaur persistence into the earliest Jurassic, To Colbert (1958), the bulk of the TJB tetrapod extinction contradicting the longstanding assumption of their extinction was in the disappearance of the “thecodonts.” These “theco- at the TJB. donts” were more recently referred to as the crurotarsans There are no demonstrable aetosaur or rauisuchian body (phytosaurs, aetosaurs and rauisuchians), though that name fossils in Rhaetian strata (Desojo et al., 2013; Lucas, 2010b; is no longer advocated by the latest cladistic analysis (Nesbitt, Nesbitt et al., 2013), though Nesbitt et al. (2013) mentioned a 2011). Phytosaurs, aetosaurs and rauisuchians are the only possible Early Jurassic rauisuchian from southern Africa, members of Colbert's “thecodonts” to have a substantial based on a single snout fragment that they also stated may be Norian or younger fossil record based on current data. Other of a large crocodylomorph. Aetosaur and rauisuchian body groups of thecodonts that have been portrayed by some as fossil records thus suggest their extinction before Rhaetian going extinct at the TJB either lack Rhaetian records (for time. example, the Ornithosuchidae: von Baczko and Ezcurra, 2013) Nevertheless, the footprint ichnogenus Brachychirotherium or have so-called Rhaetian records of problematic age, such as is known from Rhaetian strata, and Lucas and Heckert (2011) records from British fissure-fill deposits (e.g., Fraser, 1994). argued that an aetosaur was the trackmaker. Note that A non-“thecodont” group that did go extinct during the Smith et al. (2009) reported what they identified as chirothere Rhaetian is the Procolophonidae (Fig. 5). However, procolo- tracks from the Lower Jurassic Elliot Formation of Lesotho in phonids were a group of low diversity by Norian time, and southern Africa, but as Klein and Lucas (2010) noted, these many of their so-called Rhaetian records are from British tracks differ from chirothere footprints in significant ways fissure fills (e.g., Fraser, 1994). The tetrapod taxa from these and are more likely large crocodylomorph tracks. The avail- fissure fills are mostly endemic taxa of no biochronological able stratigraphic data thus suggest a three-step extinction of

Fig. 5 e 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). journal of palaeogeography 4 (2015) 331e348 339

Fig. 6 e Some biotic events across the Triassic¡Jurassic boundary.

the “crurotarsans”dﬁrst, rauisuchians by the end of the taxa, the “dromatheriids,” disappears in the Rhaetian (Lucas Norian, second, aetosaurs (based on the footprint ichnogenus and Hunt, 1994). Note, though, that the origin and diversiﬁ- Brachychirotherium) by the end of the Rhaetian and third, cation of mammaliaforms, which likely include the “droma- phytosaurs in the early Hettangian (Fig. 6). theriids,” began in the Late Triassic (e.g., Newham et al., 2014). Synapsids of the Late Triassic are dicynodonts and cyn- On present evidence, a TJB synapsid extinction is thus of a odonts (e. g., Abdala and Ribeiro, 2010; Lucas and Hunt, 1994; handful of taxa, with most taxa extinct by Rhaetian time, but Lucas and Wild, 1995). Most Late Triassic dicynodont records others crossing the TJB. are Carnian, with a couple of post-Carnian records as young as late Norian (Dzik et al., 2008; Lucas, 2015; Lucas and Wild, 5.2. Newark tetrapod record 1995; Szulc et al., 2015). The Late Triassic cynodont record is more extensive, especially in Gondwana. Traversodontids The recent case for a mass extinction of tetrapods at the TJB have a relatively diverse record in the Carnian-Norian and a has relied heavily on the Newark Supergroup record of single Rhaetian record (note that the Gondwana cynodont- tetrapod fossils (e.g., Olsen and Sues, 1986; Olsen et al., 1987, bearing strata assigned a Rhaetian age by Abdala and 1990, 2002a, 2002b; Szajna and Silvestri, 1996; Silvestri and Ribeiro, 2010 are actually Norian: Lucas, 2010b). Trithelo- Szajna, 1993)(Fig. 5). However, a close examination of all dontids cross the TJB, and a problematic group of tooth-based Triassic tetrapod taxa known from the Newark Supergroup 340 journal of palaeogeography 4 (2015) 331e348

identifies only three body-fossil taxa (indeterminate phyto- record of Anomoepus is stratigraphically higher, in the Newark saurs, the procolophonid Hypsognathus and sphenodontians) extrusive zone (Fig. 5). The crocodylomorph footprint ichno- in the youngest Triassic strata, which are strata of Rhaetian genus Batrachopus appears at the turnover level, but there are age (Huber et al., 1993; Kozur and Weems, 2010; Lucas and older Triassic body fossil records of crocodylomorphs (Klein Huber, 2003). Recent collecting has not changed that, and and Lucas, 2010; Nesbitt et al., 2013). Olsen et al. (2002a, only a few fragmentary tetrapod fossils are known from the 2002b) showed the prosauropod-dinosaur-footprint ichnoge- Newark extrusive zone and are not age diagnostic (Lucas and nus Otozoum appearing in the upper Passaic Formation, but a Huber, 2003; Lucas and Tanner, 2007b). later revision of the ichnogenus by Rainforth (2003) estab- The McCoy Brook Formation, which overlies the only CAMP lished its stratigraphically lowest record as Jurassic, in the basalt of the Fundy basin in Nova Scotia, yields a tetrapod Newark extrusive zone (Fig. 5). The lacertoid footprint ichno- assemblage generally considered Early Jurassic in age by genus Rhynchosauroides has its last Newark record in the upper vertebrate paleontologists (Fedak et al., 2015; Lucas, 1998; Passaic Formation, but this ichnogenus has Jurassic records Lucas and Huber, 2003; Lucas and Tanner, 2007a, 2007b; elsewhere (Avanzini et al., 2010). Olsen et al., 1987; Shubin et al., 1994). However, this assem- Thus, what the Newark tetrapod footprint and body-fossil blage could straddle the marine-defined TJB given that Cirilli record show is the local extinction of phytosaurs (they have et al. (2009) demonstrated that at least the lowermost McCoy a younger record elsewhere), aetosaurs, tanystropheids and Brook strata (lower part of Scots Bay Member) are Rhaetian. procolophonids (this may be the level of their global extinc- Indeed, very recently, Sues and Olsen (2015) and Fedak tion). That is the extent of the turnover in tetrapod taxa it et al. (2015) have assigned a latest Triassic (Rhaetian) age to documents, and the turnover level in the Newark is at a an assemblage of vertebrate fossils from the “fish bed” in the Rhaetian horizon, not at the TJB (Fig. 5). Scots Bay Member of the McCoy Brook Formation that in- Part of the footprint turnover in the Newark section is the cludes the crocodylomorph Protosuchus and the tritylodont local lowest occurrence of the theropod footprint ichnogenus Oligokyphus. These two taxa are known only from Jurassic Eubrontes (as defined by Olsen et al., 1998, i.e., tridactyl strata elsewhere (e.g., Lucas and Tanner, 2007a), and their theropod pes tracks longer than 28 cm). For decades, much assignment to the Rhaetian is based on inferred cyclostrati- was made of this record of Eubrontes. Thus, Olsen and Galton graphic correlations (Sues and Olsen, 2015), not on direct as- (1984) concluded that the lowest occurrence of Eubrontes sociation with Triassic fossils. Therefore, we question the age marks the base of the Jurassic, and Olsen et al. (2002a, 2002b) assignment of the “fish bed” to the Triassic, though we also later argued that the sudden appearance of Eubrontes in the note that if correctly assigned a Rhaetian age, it pushes the “earliest Jurassic” strata of the Newark Supergroup indicates a temporal record of Protosuchus and of Oligokyphus back into the dramatic size increase in theropod dinosaurs at the TJB. They Triassic, thus diminishing the apparent turnover in tetrapod interpreted this as the result of a rapid (thousands of years) taxa across the TJB. evolutionary response by the theropod survivors of a mass Because the Newark body fossil record of tetrapods is extinction and referred to it as “ecological release” (Olsen sparse across the TJB and inadequate to evaluate a possible et al., 2002a: 1307). They admitted that this can be invali- tetrapod extinction, the tetrapod footprint record in the dated by the description of Dilophosaurus-sized theropods or Newark Supergroup has been used as a proxy (e.g., Olsen and diagnostic Eubrontes tracks in verifiably Triassic-age strata. Sues, 1986; Olsen et al., 2002a, 2002b; Szajna and Silvestri, Indeed, tracks of large theropod dinosaurs assigned to 1996). However, detailed stratigraphic study of the Newark Eubrontes (or its possible synonym Kayentapus) are known from footprint record indicates nothing more than moderate turn- the Triassic of Australia, Africa (Lesotho), Europe (Great Britain, over in the footprint assemblage at a within-Rhaetian strati- France, Italy, Germany, PolandeSlovakia, Scania) and eastern graphic level below the lowest CAMP basalt sheet (Fig. 5). Greenland, invalidating the “ecological release” hypothesis Similar changes in tetrapod footprint assemblages are also (Bernardi et al. 2013; Lucas et al., 2006b; Niedzwiedzki, 2011). A known from the Chinle Group-Glen Canyon Group section of detailed review of these records indicates Carnian, Norian and the American Southwest and from the Germanic Basin (e. g., Rhaetian occurrences of tracks that meet the definition of Lucas et al., 2006a; Lucas, 2007). Eubrontes established by Olsen et al. (1998). Also, theropods The footprint turnover in the Newark section (Fig. 5)is large enough to have made at least some Eubrontes-size tracks supposedly the disappearance of four ichnogenera in the up- have long been known from the Late Triassic body-fossil re- permost Passaic Formation, and the appearance of three ich- cord (e.g., Langer et al., 2009). Thus, the sudden abundance of nogenera at that datum (Olsen et al., 2002a, 2002b). The these tracks in the Newark Supergroup cannot be explained ichnogenera that disappear represent phytosaurs (Apatopus: simply by the rapid evolution of small theropods to large size Klein and Lucas, 2013), aetosaurs (Brachychirotherium: Lucas following a mass extinction. The concept of a sudden appear- and Heckert, 2011) and tanystropheids (Gwynnedichnium: ance of Eubrontes tracks due to “ecological release” at the TJB Lucas et al., 2014). There are single Newark records of Proco- thus proposed by Olsen et al. (2002a, 2002b) can be abandoned. lophonichnium (procolophonid: Baird, 1986) just below the turnover level and a single record of Ameghinichnus (mam- 5.3. Conclusions maliaform: de Valais, 2009) above the level. According to Olsen et al. (2002a, 2002b), the ornithischian With new and more detailed stratigraphic data, the long dinosaur footprint ichnogenus Anomoepus first appears at this perceived TJB tetrapod extinction looks mostly like an artifact level, but a later detailed review of the ichnogenus by Olsen of coarse temporal resolution, the compiled correlation effect and Rainforth (2003) indicated that the lowest stratigraphic of Lucas (1994). Thus, Colbert (1958) knew, and we still know, journal of palaeogeography 4 (2015) 331e348 341

that Late Triassic tetrapod assemblages in Laurussian locales was no substantial disruption of the terrestrial ecosystem are dominated by phytosaurs, with lesser numbers of aeto- (excluding some local perturbations) across the TJB. saurs, rauisuchians and dinosaurs. Some Gondwanan Late Triassic assemblages are cynodont (mostly traversodontid) and rhynchosaur dominated. In contrast, well known Early 7. The role of CAMP volcanism Jurassic tetrapod assemblages are dinosaur dominated, with lesser numbers of crocodylomorphs and cynodonts (tritylo- In the marine realm, the end-Triassic drop in diversity was dontids), and no phytosaurs, aetosaurs or rauisuchians. But, selective but notable for the rapid loss of specific taxa, such as the former are Norian, and the latter are Sinemurian age as- conodonts, radiolarians, infaunal bivalves and ammonoids, semblages, separated in time by at least 6 million years. suggesting physical processes that strongly affected ocean Given the lack of evidence for TJB plant and arthropod bioproductivity (Tanner et al., 2004). For many years, the hy- extinctions, what could have caused a TJB tetrapod extinc- pothesis was advanced that the extinctions were associated tion? Aetosaurs, some of the cynodonts and all of the di- with a single catastrophic cause, specifically, the Man- cynodonts perceived of as suffering extinction are inferred icouagan bolide impact, the remnant crater of which spans herbivores, whereas the phytosaurs and rauisuchians are ~70 km in southern Quebec, Canada (Olsen et al., 1987, 2002a, inferred predators. Given that many herbivoresdnotably the 2002b). However, this hypothesis was firmly disproved by prosauropod dinosaursdcontinue through the TJB, a sudden radioisotopic dating of the Manicouagan structure, which trophic collapse of vertebrate communities on land cannot showed that the impact occurred ~14 Ma prior to the TJB be supported. Instead, the extinctions of tetrapods during (Hodych and Dunning, 1992; Onoue et al., 2012; Ramezani the Late Triassic appear to be a prolonged series of events et al., 2005). that began in the Norian and extended into the Hettangian Subsequently, attention on the TJB “extinctions” has (Fig. 6). 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., 6. Ecological severity 2007), but it is now well-established that these eruptions span the boundary (Cirilli et al., 2009; Kozur and Weems, 2005, McGhee et al. (2004, 2013) argued that mass extinctions need 2007, 2010; Lucas and Tanner, 2007b). Within the basins of the to be evaluated not just as biodiversity crises (crashes), but Newark Supergroup, the eruptions proceeded in three main also in terms of their ecological severity. In their scheme of episodes, separated by eruptive hiatuses during which sedi- ecological severity, they considered the TJB nonmarine ments accumulated, with the majority of the total volume extinction to be in their category I or IIa. Category I means that ejected during the initial eruptive episode (Marzoli et al., 2011). ecosystems before the extinction were replaced by new eco- The total duration of the CAMP eruptions has been esti- systems post-extinction, whereas category IIa means that the mated at ~600 ky by cyclostratigraphy (Olsen et al., 1996). The extinctions caused permanent loss of major ecosystem com- initial estimate of the size of the province, by McHone and ponents. Clearly, as we have pointed out earlier (Lucas and Puffer (1996), was ~2.3 106 km2, but Deckart et al. (1997) Tanner, 2008), this is a gross overestimate of the ecological and Marzoli et al. (1999) extended the boundaries of the significance of whatever extinctions took place on land across province to include all areas near the rift margin containing the TJB. mafic intrusions of approximately correlative age, ultimately McGhee et al. (2004) concluded that the TJB involved a outlining an area of 11 106 km2. Defining the vast potential rapid ecological replacement of Triassic mammal-like rep- aerial extent of CAMP led to an erupted lava volume calcula- tiles and rhynchosaurs by dinosaurs. However, the strati- tion of ~2 106 km3, similar to the volume calculated for the graphically highest rhynchosaurs are Revueltian (early- Deccan Traps. As noted by Tanner et al. (2004), however, this middle Norian), and the group was largely gone by the end of calculation entails the assumption that the entire area was the Carnian (Hunt and Lucas, 1991; Lucas et al., 2002; covered by lava to an average depth of hundreds of meters. Spielmann et al., 2013). Late Norian dicynodonts are now Even in the Newark basin, however, where the entire erupted known (Dzik et al., 2008; Szulc et al., 2015) and document a thickness is preserved, the total thickness varies widely, from small presence in the post Carnian, unless a putative Creta- >1 km to as little as tens of meters. Therefore, we regard this ceous record (with problematic provenance) from Australia is assumption as untenable. verified (Thulborn and Turner, 2003). The other principal It is widely acknowledged that floral and faunal turnover at group of Late Triassic mammal-like reptiles, the cynodonts, the end of the Triassic was likely driven by the CAMP erup- were of low diversity after the Carnian-Norian (Abdala and tions, which caused a significant environmental perturbation Ribeiro, 2010; Lucas and Hunt, 1994). Dinosaurs appeared as through outgassing (e. g., Belcher et al., 2010; Blackburn et al., body fossils in the Carnian and began to diversify substan- 2013; Bonis et al., 2009; Haworth and Raschi, 2014; Ruhl et al., tially in some parts of Pangea by the late Norian (e.g., Langer, 2010; Schoene et al., 2010; van de Schootbrugge et al., 2009; 2014; Langer et al., 2009). Tanner et al., 2004). Attention has focused largely on the po- Thus, the ecological severity of the end-Triassic tetrapod tential for greenhouse warming produced by the outgassed extinction is relatively low (Category IIb on the McGhee et al., CO2 (Berner and Beerling, 2007; McElwain et al., 1999; 2004 classification), and the plant extinctions do not look like Steinthorsdottir et al., 2011), but many of these studies they were ecologically severe either (see above). Clearly, there ignore the constraints of the likely volume of erupted lava and 342 journal of palaeogeography 4 (2015) 331e348

gas content. Yapp and Poths (1996), for example, estimated a of radiolarians, conodonts, bivalves, ammonoids and reef- catastrophic 18-fold increase in atmospheric CO2 across the building organisms. In the marine realm, these events are: TJB, whereas Tanner et al. (2001) calculated a much more (1) early-middle Carnian boundary (the “Carnian crisis”), modest increase (of several hundred ppm), and more recently, which included major extinctions of crinoids (especially the

Steinthorsdottir et al. (2011) calculated a CO2 doubling (by Encrinidae), echinoids, some bivalves (scallops), bryozoans, 2000e2500 ppm). The tremendous divergence in the published ammonoids, conodonts and a major change in the reef estimates of atmospheric CO2 loading from CAMP outgassing ecosystem; (2) a substantial extinction of conodonts, ammo- stems from the different approaches used to generate the noids and some bivalves (especially pectinids) at the Carnian- calculations. McElwain and collaborators (e.g., McElwain et al., Norian boundary; (3) within and at the end of the Norian, 1999; Steinthorsdottir et al., 2011) rely primarily on the sto- when there are several extinction events that had a particu- matal response of plants to elevated CO2 levels, while others larly profound effect on conodonts, marine bivalves and am- (Cleveland et al., 2008; Schaller et al., 2012; Tanner et al., 2001) monoids; and (4) a ﬁnal set of stepwise extinctions, utilize the isotopic composition of pedogenic carbonates. particularly of ammonoids and conodonts, within and at the These approaches also yield diverging estimates for the pre- end of the Rhaetian. (e.g., Flu¨ gel, 2002; Hallam, 1995; Hornung eruption atmospheric composition, knowledge of which is et al., 2007; Johnson and Simms, 1989; Lucas and Tanner, 2008; essential to determining the warming effects of CAMP out- Schafer€ and Fois, 1987; Tanner et al., 2004). gassing. Thus, there is as yet no agreement on the mass of CO2 On land, plant and tetrapod extinctions were much less released by the CAMP eruptions, much less agreement on the dramatic. Within the Carnian most workers envision a humid climatic consequences. phase (or “pluvial”) as a possible cause of some turnover of Tanner et al. (2004, 2007) drew attention to the lack of terrestrial taxa, at least in Europe (e.g., Hornung et al., 2007; consideration of the effects of SO2 outgassing by the CAMP Rigo et al., 2007; Simms and Ruffell, 1989, 1990), though this eruptions, and further demonstrated that high atmospheric has been disputed (e.g., Visscher et al., 1994). There is an end-

SO2 loading also can force changes in plant stomatal fre- Carnian event in the terrestrial tetrapod record, with some quency, an effect eventually noticed by other workers (Bacon evolutionary turnover across the CarnianeNorian boundary et al., 2013). The environmental effects of large sulfur emis- (Benton, 1986, 1991, 1993; Lucas, 1994). Extinctions on land sions during prolonged flood basalt eruptions are not clear, closer to the TJB look even less significant. The amphibian, but the formation of H2SO4 aerosols, which in addition to archosaur and synapsid extinctions of the Late Triassic are causing acidic precipitation, are known to increase atmo- not concentrated at the TJB, but instead occur stepwise, spheric opacity and result in reduced short-wave radiant beginning in the Norian and extending into the Jurassic heating, causing global cooling (Sigurdsson, 1990). Fluorine (Fig. 6). Changes in the land plants are complex, diachronous and chlorine volatile emissions during the CAMP eruptions and likely climate driven evolutionary changes over back- also would have contributed to the acidification of surface ground extinction rates, not a serious extinction or set of waters and terrestrial environments (Guex et al., 2004; Lucas extinctions. and Tanner, 2008; van de Schootbrugge et al., 2009). We conclude that no significant extinction took place on Thus, a temporary loss of phytoplankton productivity in land at the TJB. Indeed, the idea of a single mass extinction on marine surface waters is an entirely reasonable consequence land at the TJB has led to a search for the cause of the “mass of the CAMP eruptions. The subsequent “trickle-down” effects extinction” and drawn attention away from what were actu- through the marine trophic system are clear, even without ally a series of biotic events that took place throughout the climate change. Primary producers would have been most Late Triassic (Fig. 6). Research should now focus on these profoundly affected by the changes in water chemistry, but multiple extinctions and their causes, not on a single extinc- higher level consumers would also have felt ecological pres- tion event. Perhaps the most interesting question not yet sure, although perhaps less strongly. The compounding ef- addressed by most researchers is why a prolonged (at least 30 fects of climate change e rapid, short-term cooling forced by million years) interval of elevated extinction rates occurred

H2SO4 aerosols and slower, longer-term warming driven by during the Late Triassic. e CO2 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 Acknowledgments caused significant environmental perturbations (cooling, warming, acidification) through outgassing, but the effects on We are grateful to Baas van de Schootbrugge for encouraging the nonmarine biota appear to have been palaeogeo- us to publish this article. We also thank Professor Li, Jin-Geng graphically localized, transient and not catastrophic. Sha, Shu-Zhong Shen and two anonymous reviewers for their helpful reviews of this article. 8. End Triassic nonmarine biotic events references 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). Abdala, F., Ribeiro, A.M., 2010. Distribution and diversity patterns Most of the evidence for this comes from the marine biota, of Triassic cynodonts (Therapsida, Cynodontia) in Gondwana. with multiple Late Triassic, and often substantial extinctions Palaeogeogr. Palaeoclimatol. Palaeoecol. 286, 202e217. journal of palaeogeography 4 (2015) 331e348 343

Ash, S., 1986. Fossil plants and the Triassic-Jurassic boundary. In: Cascales-Minana,~ B., Cleal, C.J., 2011. Plant fossil record and Padian, K. (Ed.), The Beginning of the Age of Dinosaurs. survival analysis. Lethaia 45, 71e82. Cambridge University Press, Cambridge, pp. 21e30. Cirilli, S., 2010. Uppermost Triassic-lowermost Jurassic Avanzini, M., Pinuela, L., Garcia-Ramos, J.C., 2010. First report of a palynology and palynostratigraphy: a review. In: Lucas, S.G. Late Jurassic lizard-like footprint (Asturias, Spain). J. Iber. Geol. (Ed.), The Triassic Timescale, Special Publication, 334. 36, 175e180. Geological Society, London, pp. 285e314. Bacon, K.L., Belcher, C.M., Haworth, M., McElwain, J.C., 2013. Cirilli, S., Marzoli, A., Tanner, L.H., Bertrand, H., Buratti, N.,

Increased atmospheric SO2 detected from changes in leaf Jourdan, F., Bellieni, G., Kontak, D., Renne, P.R., 2009. Late physiognomy across the Triassic-Jurassic boundary interval of Triassic onset of the Central Atlantic magmatic province East Greenland. PLOS One 8 (4), e60614. (CAMP) volcanism in the Fundy Basin (Nova Scotia): new von Baczko, M.B., Ezcurra, M.D., 2013. Ornithosuchidae: a group of stratigraphic constraints. Earth Planet. Sci. Lett. 286, 514e525. Triassic archosaurs with a unique ankle joint. In: Nesbitt, S.J., Cleal, C.J., 1993a. Pteridophyta. In: Benton, M.J. (Ed.), The Fossil Desojo, J.B., Irmis, R.B. (Eds.), Anatomy, Phylogeny and Record 2. Chapman and Hall, London, pp. 779e794. Palaeobiology of Early Archosaurs and their Kin, Special Cleal, C.J., 1993b. Gymnospermophyta. In: Benton, M.J. (Ed.), The Publications, 379. Geological Society, London, pp. 187e202. Fossil Record 2. Chapman and Hall, London, pp. 795e808. Baird, D., 1986. Some Upper Triassic reptiles, footprints, and an Cleveland, D.M., Nordt, L.C., Dworkin, S.I., Atchley, S.C., 2008. amphibian from New Jersey. Mosasaur 3, 125e153. Pedogenic carbonate isotopes as evidence for extreme climatic Balini, M., Lucas, S.G., Jenks, J.M., Spielmann, J.A., 2010. Triassic events preceding the Triassic-Jurassic boundary: implications ammonoid biostratigraphy: an overview. In: Lucas, S.G. (Ed.), for the biotic crisis? GSA Bull. 120, 1408e1415. The Triassic Timescale, Special Publication, 334. Geological Colbert, E.H., 1949. Progressive adaptations as seen in the fossil Society, London, pp. 221e262. record. In: Jepsen, G.L., Mayr, E., Simpson, G.G. (Eds.), Genetics, Bambach, R.K., Knoll, A.H., Wang, S.C., 2004. Origination, Paleontology and Evolution. Princeton University Press, extinction, and mass depletion of marine diversity. Princeton, pp. 390e402. Paleobiology 20, 522e542. Colbert, E.H., 1958. Triassic tetrapod extinction at the end of the Bandyopadhyay, S., Sengupta, D.P., 2006. Vertebrate faunal Triassic Period. Proc. Natl. Acad. Sci. U. S. A. 44, 973e977. turnover during the Triassic-Jurassic transition: an Indian Cornet, B., 1977. The Palynostratigraphy and Age of the Newark scenario. N. M. Mus. Nat. Hist. Sci. Bull. 37, 77e85. Supergroup (Ph.D. thesis). University Park, PA, Pennsylvania Belcher, C.M., Mander, L., Rein, G., Jervis, F.X., Haworth, M., State University, pp. 1e505. Hesselbo, S.P., Glasspool, I.J., McElwain, J.C., 2010. Increased Cornet, B., Olsen, P.E., 1985. A summary of the biostratigraphy of fire activity at the Triassic/Jurassic boundary in Greenland due the Newark Supergroup of eastern North America with to climate-driven floral change. Nat. Geosci. 3, 426e429. comments on provinciality. In: Weber, R. (Ed.), III Congreso Benton, M.J., 1986. More than one event in the Late Triassic mass Latinoamericano de Paleontologia Mexico, Simposio Sobre extinction. Nature 321, 857e861. Floras del Triasico Tardio, su Fitogeografia y Paleoecologia, Benton, M.J., 1991. What really happened in the Late Triassic? UNAM Instituto de Geologia, Mexico City, pp. 67e81. Hist. Biol. 5, 263e278. Dam, G., Surlyk, F., 1993. Cyclic sedimentation in a large wave- Benton, M.J., 1993. Reptilia. In: Benton, M.J. (Ed.), The Fossil Record and storm-dominated anoxic lake, Kap Stewart Formation 2. Chapman and Hall, London, pp. 681e715. (Rhaetian-Sinemurian), Jameson Land, East Greenland. Int. Benton, M.J., 1994. Late Triassic to Middle Jurassic extinctions Assoc. Sedimentol. Spec. Publ. 18, 419e448. among continental tetrapods: testing the pattern. In: Deckart, K., Feraud, G., Bertrand, H., 1997. Age of Jurassic Fraser, N.C., Sues, H.-D. (Eds.), In the Shadow of the Dinosaurs. continental tholeiites of French Guyana, Surinam and Guinea: Cambridge University Press, Cambridge, pp. 366e397. Implications for the initial opening of the Central Atlantic Bernardi, M., Petti, F.M., Porchetti, S.D., Avanzini, M., 2013. Large Ocean. Earth Planet. Sci. Lett. 150, 205e220. tridactyl footprints associated with a diverse ichnofauna from Desojo, J.B., Heckert, A.B., Martz, J.W., Parker, W.G., Schoch, R.R., the Carnian of the Southern Alps. N. M. Mus. Nat. Hist. Sci. Small, B.J., Sulej, T., 2013. Aetosauria: a clade of armoured Bull. 61, 48e54. pseudosuchians from the Upper Triassic continental beds. In: Berner, R.A., Beerling, D.J., 2007. Volcanic degassing necessary to Nesbitt, S.J., Desojo, J.B., Irmis, R.B. (Eds.), Anatomy, e produce CaCO3 undersaturated ocean at the Triassic Jurassic Phylogeny and Palaeobiology of Early Archosaurs and their boundary. Palaeogeogr. Palaeoclimatol. Palaeoecol. 244, Kin, Special Publications, 379. Geological Society, London, 368e373. pp. 203e240. Blackburn, T.J., Olsen, P.E., Bowring, S.A., McLean, N.M., Dzik, J., Sulej, T., Niedzwiedzki, G., 2008. A dicynodont-theropod Kent, D.V., Puffer, J., McHone, G., Rasbury, E.T., Et- association in the latest Triassic of Poland. Acta Palaeontol. Touhami, M., 2013. Zircon U-Pb geochronology links the end- Pol. 53, 733e738. Triassic extinction with the Central Atlantic Magmatic Edwards, D., 1993. Bryophyta. In: Benton, M.J. (Ed.), The Fossil Province. Science 340, 941e945. Record 2. Chapman and Hall, London, pp. 775e778. Bonis, N.R., Ku¨ rschner, W.M., 2012. Vegetation history, diversity Fedak, T.J., Sues, H.-D., Olsen, P.E., 2015. First record of the patterns, and climate change across the Triassic/Jurassic tritylodontid cynodont Oligokyphus and cynodont postcranial boundary. Paleobiology 38, 240e264. bones from the McCoy Brook Formation of Nova Scotia, Bonis, N.R., Ku¨ rschner, W., Krystyn, L., 2009. A detailed Canada. Can. J. Earth Sci. 52, 244e249. palynological study of the Triassic-Jurassic transition in key Fisher, M.J., Dunay, R.E., 1981. Palynology and the Triassic/ sections of the Eiberg basin (Northern calcareous Alps, Jurassic boundary. Rev. Palaeobot. Palynol. 34, 129e135. Austria). Rev. Palaeobot. Palynol. 156, 376e400. Flu¨ gel, E., 2002. Triassic reef patterns. In: Kiessling, W., Flu¨ gel, E., Brugman, W.A., 1983. Permian-Triassic Palynology. State Golonka, J. (Eds.), Phanerozoic Reef Patterns, SEPM Special University Utrecht, Utrecht, pp. 1e121. Publication, 72, pp. 391e463. Burgoyne, P.M., van Wyk, A.E., Anderson, J.M., Schrire, B.D., 2005. Fowell, S.J., Olsen, P.E., 1993. Time calibration of Triassic-Jurassic Phanerozoic evolution of plants on the African plate. J. Afr. microfloral turnover, eastern North America. Tectonophysics Earth Sci. 43, 13e52. 222, 361e369. 344 journal of palaeogeography 4 (2015) 331e348

Fowell, S.J., Traverse, A., 1995. Palynology and age of the upper Huber, P., Lucas, S.G., Hunt, A.P., 1993. Vertebrate biochronology Blomidon Formation, Fundy basin, Nova Scotia. Rev. of the Newark supergroup Triassic, eastern North America. N. Palaeobot. Palynol. 86, 211e233. M. Mus. Nat. Hist. Sci. Bull. 3, 179e186. Fowell, S.J., Cornet, B., Olsen, P.E., 1994. Geologically rapid Late Hunt, A.P., 1993. A revision of the Metoposauridae (Amphibia: Triassic extinctions: palynological evidence from the Newark Temnospondyli) of the Late Triassic with description of a new supergroup. Geol. Soc. Am. Spec. Pap. 288, 197e206. genus from the western United States. Mus. North. Ariz. Bull. Fraser, N.C., 1994. Assemblages of small tetrapods from British 59, 67e97. Late Triassic fissure deposits. In: Fraser, N.C., Sues, H.-D. Hunt, A.P., Lucas, S.G., 1991. A new rhynchosaur from West Texas (Eds.), In the Shadow of the Dinosaurs. Cambridge University (USA) and the biochronology of Late Triassic rhynchosaurs. Press, Cambridge, pp. 214e226. Palaeontology 34, 191e198. Galli, M.T., Jadoul, F., Bernasconi, S.M., Weissert, H., 2005. Johnson, L.A., Simms, M.J., 1989. The timing and cause of Late Anomalies in global carbon cycling and extinction at the Triassic marine invertebrate extinctions: evidence from Triassic/Jurassic boundary: evidence from a marine C- scallops and crinoids. In: Donovan, K. (Ed.), Mass Extinctions: isotope record. Palaeogeogr. Palaeoclimatol. Palaeoecol. 16, Processes and Evidence. Columbia University Press, New York, 203e214. pp. 174e194. Giordano, N., Rigo, M., Ciarapica, G., Bertinelli, A., 2010. New Kelber, K.-P., 1998. Phytostratigraphische aspekte der biostratigraphical constraints for the Norian/Rhaetian makrofloren des su¨ ddeutschen Keupers. Doc. Naturae 117, boundary: data from Lagonegro basin, Southern Appenines, 89e115. Italy. Lethaia 43, 573e586. Kiessling, W., Aberhan, M., Brenneis, B., Wagner, P.J., 2007. Gomez, J.J., Goy, A., Barron, E., 2007. Events around the Triassic- Extinction trajectories of benthic organisms across the Jurassic boundary in northern and eastern Spain: a review. Triassic-Jurassic boundary. Palaeogeogr. Palaeoclimatol. Palaeogeogr. Palaeoclimatol. Palaeoecol. 244, 89e110. Palaeoecol. 244, 201e222. Grimaldi, D., Engel, M.S., 2005. Evolution of the Insects. Klein, H., Lucas, S.G., 2010. The Triassic footprint record of Cambridge University Press, Cambridge, pp. 1e755. crocodylomorphsda critical re-evaluation. N. M. Mus. Nat. Guex, J., Bartolin, A., Atudorei, V., Taylor, D., 2004. High- Hist. Sci. Bull. 51, 55e60. resolution ammonite and carbon isotope stratigraphy across Klein, H., Lucas, S.G., 2013. The Late Triassic tetrapod ichnotaxon the Triassic-Jurassic boundary at New York Canyon (Nevada). Apatopus lineatus (Bock 1952) and its distribution. N. M. Mus. Earth Planet. Sci. Lett. 225, 29e41. Nat. Hist. Sci. Bull. 61, 313e324. Hallam, A., 1995. Major bio-events in the Triassic and Jurassic. In: Knoll, A.H., 1984. Patterns of extinction in the fossil record of Walliser, O. (Ed.), Global Events and Event Stratigraphy. vascular plants. In: Nitecki, M. (Ed.), Extinction. University of Springer, Berlin, pp. 265e283. Chicago Press, Chicago, pp. 21e68. Hallam, A., 2002. How catastrophic was the end-Triassic mass Kozur, H.W., Bachmann, G.H., 2005. Correlation of the Germanic extinction? Lethaia 35, 147e157. Triassic with the international scale. Albertiana 32, 21e35. Hallam, A., Wignall, P.B., 1997. Mass Extinctions and Their Kozur, H.W., Bachmann, G.H., 2008. Updated correlation of the Aftermath. Oxford University Press, Oxford, pp. 1e320. Germanic Triassic with the Tethyan scale and assigned Harris, T.M., 1937. The fossil flora of Scoresby Sound East numeric ages. Berichte Geol. Bundesanst. 76, 53e58. Greenland, Part 5: stratigraphic relations of the plant beds. Kozur, H.W., Weems, R.E., 2005. Conchostracan evidence for a Meddelelser Om. Grønl. 112, 1e112. late Rhaetian to early Hettangian age for the CAMP volcanic Haworth, M., Raschi, A., 2014. An assessment of the use of event in the Newark Supergroup, and a Sevatian (late Norian) epidermal micro-morphological features to estimate leaf age for the immediately underlying beds. Hallesches Jahrb. economics of Late Triassic-Early Jurassic fossil Ginkgoales. Geowiss. B27, 21e51. Rev. Palaeobot. Palynol. 205, 1e8. Kozur, H.W., Weems, R.E., 2007. Upper Triassic conchostracan Hesselbo, S.P., Robinson, S.A., Surlyk, F., Piasecki, S., 2002. biostratigraphy of the continental rift basins of eastern North Terrestrial and marine extinction at the Triassic-Jurassic America: Its importance for correlating Newark Supergroup boundary synchronized with major carbon-cycle events with the Germanic Basin and the international geologic perturbation: a link to initiation of massive volcanism? time scale. N. M. Mus. Nat. Hist. Sci. Bull. 41, 137e188. Geology 30, 251e254. Kozur, H.W., Weems, R.E., 2010. The biostratigraphic importance Hillebrandt, A.V., Krystyn, L., Ku¨ rschner, W.M., Bonis, N.R., of conchostracans in the continental Triassic of the northern Ruhl, M., Richoz, S., Schobben, M.A.N., Ulrichs, M., Bown, P.R., hemisphere. In: Lucas, S.G. (Ed.), The Triassic Timescale, Kment, K., McRoberts, C.A., Simms, M., Tomasovych,~ A., 2013. Special Publication, 334. Geological Society, London, The global stratotype section and point (GSSP) for the base of pp. 315e417. the Jurassic System at Kuhjoch (Karwendel Mountains, Krystyn, L., Boquerel, H., Kuerschner, W., Richoz, S., Gallet, Y., Northern Calcareous Alps, Tyrol, Austria). Episodes 36, 2007. Proposal for a candidate GSSP for the base of the 162e198. Rhaetian Stage. N. M. Mus. Nat. Hist. Sci. Bull. 41, 189e199. Hodych, J.P., Dunning, G.R., 1992. Did the Manicouaga impact Kuerschner, W.M., Bonis, N.R., Krystyn, L., 2007. Carbon-isotope trigger end-of-Triassic mass extinction? Geology 20, 51e54. stratigraphy and palynostratigraphy of the Triassic-Jurassic Hornung, T., Brandner, R., Krystyn, L., Jaochimski, M.M., Keim, L., transition in the Tiefengraben sectiondNorthern Calcareous 2007. Multistratigraphic constrainst on the NW Tethyan Alps (Austria). Palaeogeogr. Palaeoclimatol. Palaeoecol. 244, “Carnian crisis”. N. M. Mus. Nat. Hist. Sci. Bull. 41, 59e67. 257e280. Hounslow, M.W., Muttoni, G., 2010. The geomagnetic polarity Ku¨ rschner, W.M., Herngreen, G.F.W., 2010. Triassic palynology of timescale for the Triassic: Linkage to stage boundary central and northwestern Europe: a review of palynofloral definitions. In: Lucas, S.G. (Ed.), The Triassic Timescale, diversity patterns and biostratigraphic subdivisions. In: Special Publication, 334. Geological Society, London, Lucas, S.G. (Ed.), The Triassic Timescale, Special Publication, pp. 61e102. 334. Geological Society, London, pp. 263e283. Hounslow, M.W., Posen, P.E., Warrington, G., 2004. Labandeira, C.C., Sepkoski Jr., J.J., 1993. Insect diversity in the Magnetostratigraphy and biostratigraphy of the Upper fossil record. Science 261, 310e315. Triassic and lowermost Jurassic succession, St. Audrie's Bay, Langer, M.C., 2014. The origins of Dinosauria: much ado about UK. Palaeogeogr. Palaeoclimatol. Palaeoecol. 213, 331e358. nothing. Palaeontology 2014, 1e10. journal of palaeogeography 4 (2015) 331e348 345

Langer, M.C., Ezcurra, M.D., Bittencourt, J.S., Novas, F.E., 2009. The distribution of the theropod footprint ichnogenus Eubrontes. origin and early evolution of dinosaurs. Biol. Rev. 84, 1e56. N. M. Mus. Nat. Hist. Sci. Bull. 37, 86e93. Long, R.A., Murry, P.A., 1995. Late Triassic (Carnian and Norian) Lucas, S.G., Hunt, A.P., Heckert, A.B., Spielmann, J.A., 2007a. tetrapods from the southwestern United States. N. M. Mus. Global Triassic tetrapod biostratigraphy and biochronology: Nat. Hist. Sci. Bull. 4, 1e254. 2007 status. N. M. Mus. Nat. Hist. Sci. Bull. 41, 229e240. Lucas, S.G., 1994. Triassic tetrapod extinctions and the compiled Lucas, S.G., Taylor, D.G., Guex, J., Tanner, L.H., Krainer, K., 2007b. correlation effect. Can. Soc. Pet. Geol. Mem. 17, 869e875. The proposed global stratotype section and point for the base Lucas, S.G., 1998. Global Triassic tetrapod biostratigraphy and of the Jurassic System in the New York Canyon area, Nevada, biochronology. Palaeogeogr. Palaeoclimatol. Palaeoecol. 143, USA. N. M. Mus. Nat. Hist. Sci. Bull. 40, 139e168. 347e384. Lucas, S.G., Tanner, L.H., Donohoo-Hurley, L.L., Geissman, J.W., Lucas, S.G., 2007. Tetrapod footprint biostratigraphy and Kozur, H.W., Heckert, A.B., Weems, R.E., 2011. Position of the biochronology. Ichnos 14, 5e38. Triassic-Jurassic boundary and timing of the end- Triassic Lucas, S.G., 2008. Global Jurassic tetrapod biochronology. Vol. extinctions on land: data from the moenave formation on the Jurass. 6, 99e108. southern Colorado Plateau, USA. Palaeogeogr. Palaeoecol. Lucas, S.G., 2010a. The Triassic timescale: an introduction. In: Palaeoclimatol. 302, 194e205. Lucas, S.G. (Ed.), The Triassic Timescale, Special Publication, Lucas, S.G., Tanner, L.H., Kozur, H.W., Weems, R.E., Heckert, A.B., 334. Geological Society, London, pp. 1e16. 2012. The late Triassic timescale: age and correlation of the Lucas, S.G., 2010b. The Triassic timescale based on nonmarine Carnian-Norian boundary. Earth Sci. Rev. 114, 1e8. tetrapod biostratigraphy and biochronology. In: Lucas, S.G. Lucas, S.G., Szajna, M.J., Lockley, M.G., Fillmore, D.L., (Ed.), The Triassic Timescale, Special Publication, 334. Simpson, E.L., Klein, H., Boyland, J., Hartline, B.W., 2014. The Geological Society, London, pp. 447e500. middle-late Triassic tetrapod footprint ichnogenus Lucas, S.G., 2013a. Plant megafossil biostratigraphy and Gwynnedichnium. N. M. Mus. Nat. Hist. Sci. Bull. 62, 135e156. biochronology, Upper Triassic Chinle Group, western USA. N. Maisch, M.W., Kapitzke, M., 2010. A presumably marine M. Mus. Nat. Hist. Sci. Bull. 61, 354e365. phytosaur (Reptilia: Archosauria) from the pre-planorbis beds Lucas, S.G., 2013b. A new Triassic timescale. N. M. Mus. Nat. Hist. (Hettangian) of England. Neues Jahrb. fu¨ r Geol. Palaontol.€ Abh. Sci. Bull. 61, 366e374. 257, 373e379. Lucas, S.G., 2015. Age and correlation of Late Triassic tetrapods Mander, L., Ku¨ rschner, W.M., McElwain, J.C., 2010. An explanation from southern Poland. Ann. Soc. Geol. Pol. http://dx.doi.org/ for conflicting records of Triassic-Jurassic plant diversity. Proc. 10.14241/asgp.2015.024 (in press). Natl. Acad. Sci. U. S. A. 107, 15351e15356. Lucas, S.G., Heckert, A.B., 2011. Late Triassic aetosaurs as the Mander, L., Wesseln, C.J., McElwain, J.C., Punyasena, S.W., 2012. trackmaker of the tetrapod footprint ichnotaxon. Tracking taphonomic regimes using chemical and mechanical Brachychirotherium. Ichnos 18, 197e208. damage of pollen and spores: an example from the Triassic- Lucas, S.G., Huber, P., 2003. Vertebrate biostratigraphy and Jurassic mass extinction. PLOS ONE 7 (11), e49153. biochronology of the nonmarine Late Triassic. In: Mander, L., Ku¨ rschner, W.M., McElwain, J.C., 2013. LeTourneau, P.M., Olsen, P.E. (Eds.), The Great Rift Valleys of Palynostratigraphy and vegetation history of the Triassic- Pangea in Eastern North America, Sedimentology, Jurassic transition in East Greenland. J. Geol. Soc. Lond. 170, Stratigraphy, and Paleontology, vol. 2. Columbia University 37e46. Press, New York, pp. 143e191. Marzoli, A., Renne, P.R., Piccirillo, E.M., Ernesto, M., Bellieni, G., Lucas, S.G., Hunt, A.P., 1994. The chronology and DeMin, A., 1999. Extensive 200-million-year-old continental paleobiogeography of mammalian origins. In: Fraser, N.C., flood basalts of the central Atlantic Magmatic province. Sues, H.-D. (Eds.), In the Shadow of the Dinosaurs. Cambridge Science 284, 616e618. University Press, Cambridge, pp. 335e351. Marzoli, A., Bertrand, H., Knight, K.B., Cirilli, S., Buratti, N., Lucas, S.G., Tanner, L.H., 2004. Late Triassic extinction events. Verati, C., Nomade, S., Renne, P.R., Youbi, N., Martini, R., Albertiana 31, 31e40. Allenbach, N., Neuwerth, R., Rapaille, C., Zaninetti, L., Lucas, S.G., Tanner, L.H., 2007a. Tetrapod biostratigraphy and Zaninetti, L., Bellieni, G., 2004. Synchrony of the biochronology of the Triassic-Jurassic transition on the Central Atlantic magmatic province and the southern Colorado Plateau, USA. Palaeogeogr. Palaeoclimatol. Triassic-Jurassic boundary climate and biotic crisis. GSA Bull. Palaeoecol. 244, 242e256. 32, 973e976. Lucas, S.G., Tanner, L.H., 2007b. The nonmarine Triassic-Jurassic Marzoli, A., Jourdan, F., Puffer, J.H., Cuppone, T., Tanner, L.H., boundary in the Newark supergroup of eastern North Weems, R.E., Bertrand, H., Cirilli, S., Bellieni, G., De Min, A., America. Earth Sci. Rev. 84, 1e20. 2011. Timing and duration of the Central Atlantic magmatic Lucas, S.G., Tanner, L.H., 2008. Reexamination of the end-Triassic province in the Newark and Culpeper basins, eastern U.S.A. mass extinction. In: Elewa, A.M.T. (Ed.), Mass Extinction. Lithos 122, 175e188. Springer Verlag, New York, pp. 66e103. McCune, A.R., Schaeffer, B., 1986. Triassic and Jurassic fishes: Lucas, S.G., Wild, R., 1995. A Middle Triassic dicynodont from patterns of diversity. In: Padian, K. (Ed.), The Beginning of the Germany and the biochronology of Triassic dicynodonts. Age of Dinosaurs. Cambridge University Press, Cambridge, Stuttg. Beitrage€ zur Naturkd. 220, 1e16. pp. 171e181. Lucas, S.G., Heckert, A.B., Hotton III, N., 2002. The rhynchosaur McElwain, J.C., Punyasena, S.W., 2007. Mass extinction events and Hyperodapedon from the Upper Triassic of Wyoming and its the plant fossil record. Trends Ecol. Evol. 22, 548e557. global biochronological significance. N. M. Mus. Nat. Hist. Sci. McElwain, J.C., Beerling, D.J., Woodward, F.I., 1999. Fossil plants Bull. 21, 149e156. and global warming at the Triassic-Jurassic boundary. Science Lucas, S.G., Lockley, M.G., Hunt, A.P., Milner, A.R.C., Tanner, L.H., 285, 1386e1390. 2006a. Tetrapod footprint biostratigraphy of the Triassic- McElwain, J.C., Popa, M.E., Hesselbo, S.P., Haworth, M., Jurassic transition in the American Southwest. N. M. Mus. Nat. Surlyk, F., 2007. Macroecological responses of terrestrial Hist. Sci. Bull. 37, 105e108. vegetation to climatic and atmospheric change across the Lucas, S.G., Klein, H., Lockley, M.G., Spielmann, J.A., Gierlinski, G., Triassic/Jurassic boundary in East Greenland. Paleobiology Hunt, A.P., Tanner, L.H., 2006b. Triassic-Jurassic stratigraphic 33, 547e573. 346 journal of palaeogeography 4 (2015) 331e348

McElwain, J.C., Wagner, P.J., Hesselbo, S.P., 2009. Fossil plant Beginning of the Age of Dinosaurs. Cambridge University relative abundances indicate sudden loss of late Triassic Press, Cambridge, pp. 321e351. biodiversity in East Greenland. Science 324, 1554e1556. Olsen, P.E., Shubin, N.H., Anders, M.H., 1987. New Early Jurassic McGhee Jr., G.R., Sheehan, P.M., Bottjer, D.J., Droser, M.L., 2004. tetrapod assemblages constrain Triassic-Jurassic tetrapod Ecological ranking of Phanerozoic biodiversity crises: extinction event. Science 237, 1025e1029. ecological and taxonomic severities are decoupled. Olsen, P.E., Fowell, S.J., Cornet, B., 1990. The Triassic/Jurassic Palaeogeogr. Palaeoclimatol. Palaeoecol. 211, 289e297. boundary in continental rocks of eastern North America; a McGhee Jr., G.R., Clapham, M.E., Sheehan, P.M., Bottjer, D.J., progress report. Geol. Soc. Am. Spec. Pap. 247, 585e593. Droser, M.L., 2013. A new ecological-severity ranking of major Olsen, P.E., Schlische, R.W., Fedosh, M.S., 1996. 580 ky duration of Phanerozoic biodiversity crises. Palaeogeogr. Palaeoclimatol. the Early Jurassic flood basalt event in eastern North America Palaeoecol. 370, 260e270. estimated using Milankovitch cyclostratigraphy. Mus. North. McHone, J.G., Puffer, J.H., 1996. Hettangian Flood Basalts Across Ariz. Bull. 60, 11e22. the Pangaean Rift. In: Connecticut State Geological and Olsen, P.E., Smith, J.B., McDonald, N.G., 1998. Type material of the Natural History Survey Natural Resources Center type species of the classic theropod footprint genera Eubrontes, Miscellaneous Report, vol. 1, p. 29. Anchisauripus, and Grallator (Early Jurassic, Hartford and Milner, A.R., 1993. Amphibian-grade Tetrapoda. In: Benton, M.J. Deerfield basins, Connecticut and Massachusetts, U. S. A. J. (Ed.), The Fossil Record 2. Chapman and Hall, London, Vertebr. Paleontol. 18, 586e601. pp. 665e679. Olsen, P.E., Kent, D.V., Sues, H.D., Koeberl, C., Huber, H., Milner, A.R., 1994. Late Triassic and Jurassic amphibians: fossil Montanari, A., Rainforth, E.C., Powell, S.J., Szajna, M.J., record and phylogeny. In: Fraser, N.C., Sues, H.-D. (Eds.), In the Hartline, B.W., 2002a. Ascent of dinosaurs linked to an iridium Shadow of the Dinosaurs. Cambridge University Press, anomaly at the Triassic-Jurassic boundary. Science 296, Cambridge, pp. 5e22. 1305e1307. Milner, A.R.C., Kirkland, J.I., Birthisel, T.A., 2006. The geographic Olsen, P.E., Koeberl, C., Huber, H., Montanari, A., Fowell, S.J., Et- distribution and biostratigraphy of Late Triassic-Early Jurassic Touhani, M., Kent, D.V., 2002b. The continental Triassic- freshwater fish faunas of the western United States. N. M. Jurassic boundary in central Pangea: recent progress and Mus. Nat. Hist. Sci. Bull. 37, 522e529. preliminary report of an Ir anomaly. Geol. Soc. Am. Spec. Pap. Nesbitt, S.J., 2011. The early evolution of archosaurs: 356, 505e522. relationships and the origin of major clades. Bull. Am. Mus. Olsen, P.E., Kent, D.V., Whiteside, J.H., 2011. Implications of the Nat. Hist. 352, 1e292. Newark Supergroup-based astrochronology and geomagnetic Nesbitt, S.J., Brusatte, S.L., Desojo, J.B., Liparini, A., De polarity time scale (Newark-APTS) for the tempo and mode of Franca, M.A.G., Weinbaum, J.C., Gower, D.J., 2013. Rauisuchia. the early diversification of the Dinosauria. Earth Environ. Sci. In: Nesbitt, S.J., Desojo, J.B., Irmis, R.B. (Eds.), Anatomy, Trans. R. Soc. Edinb. 101, 201e229. Phylogeny and Palaeobiology of Early Archosaurs and their Olsen, P.E., Reid, J.C., Taylor, K.B., Whiteside, J.H., Kent, D.V., 2015. Kin, Special Publications, 379. Geological Society, London, Revised stratigraphy of Late Triassic age strata of the Dan pp. 241e274. River basin (Virginia and North Carolina, USA) based on drill Newham, E., Benson, R., Upchurch, P., Goswani, A., 2014. core and outcrop data. Southeast. Geol. 51, 1e31. Mesozoic mammaliaform diversity: the effect of Onoue, T., Sato, H., Nakamura, T., Noguchi, T., Hidaka, Y., sampling corrections on reconstructions of evolutionary Shirai, N., Ebihara, M., Osawa, T., Hatsukawa, Y., Toh, Y., dynamics. Palaeogeogr. Palaeoclimatol. Palaeoecol. 412, Koizumi, M., Harada, H., Orchard, M.J., Nedachi, M., 2012. 32e44. Deep-sea record of impact apparently unrelated to mass Niedzwiedzki, G., 2011. A Late Triassic dinosaur-dominated extinction in the Late Triassic. Proc. Natl. Acad. Sci. 109, ichnofauna from the Tomanova Formation of the Tatra 19134e19139. Mountains, central Europe. Acta Palaeontol. Pol. 56, Orbell, G., 1973. Palynology of the British Rhaeto-Liassic. Bull. 291e300. Geol. Soc. G. B. 44, 1e44. Niklas, K.J., Tiffney, B.H., Knoll, A.H., 1983. Patterns in vascular Orchard, M.J., 2010. Triassic conodonts and their role in stage land plant diversification: a statistical analysis at the species boundary definition. In: Lucas, S.G. (Ed.), The Triassic level. Nature 303, 614e616. Timescale, Special Publication, 334. Geological Society, Ogg, J.G., 2012a. Triassic. In: Gradstein, F.M., Ogg, J.G., London, pp. 139e161. Schmitz, M.D., Ogg, G.M. (Eds.), The Geologic Timescale 2012, Orchard, M.J., 2013. Five new genera of conodonts from the vol. 2. Elsevier, Amsterdam, pp. 681e730. Carnian-Norian boundary beds of Black Bear Ridge, northeast Ogg, J.G., 2012b. Jurassic. In: Gradstein, F.M., Ogg, J.G., British Columbia, Canada. N. M. Mus. Nat. Hist. Sci. Bull. 61, Schmitz, M.D., Ogg, G.M. (Eds.), The Geologic Timescale 2012, 445e457. vol. 2. Elsevier, Amsterdam, pp. 731e791. Orchard, M.J., 2014. Conodonts from the Carnian-Norian Ogg, J.G., Huang, C., Hinnov, L., 2014. Triassic timescale status: a boundary (Upper triassic) of Black Bear Ridge, northeastern brief overview. Albertiana 41, 3e30. British Columbia, Canada. N. M. Mus. Nat. Hist. Sci. Bull. 64, Olsen, P.E., Galton, P.M., 1984. A review of the reptile and 1e139. amphibian assemblages from the Stormberg of South Africa, Pedersen, K.R., Lund, J.J., 1980. Palynology of the plant-bearing with special emphasis on the footprints and the age of the Rhaetian to Hettangian Kap Stewart formation, Scoresby Stormberg. Palaeontol. Afr. 25, 87e110. Sund, East Greenland. Rev. Palaeobot. Palynol. 31, 1e69. Olsen, P.E., Rainforth, E.C., 2003. The early Jurassic ornithischian Pienkowski, G., Niedzwiedzki, G., Waksmundzka, M., 2011. dinosaur ichnogenus Anomoepus. In: LeTourneau, P.M., Sedimentological, palynological and geochemical studies of Olsen, P.E. (Eds.), The Great Rift Valleys of Pangea in Eastern the terrestrial Triassic-Jurassic boundary in northwestern North America, Sedimentology, Stratigraphy, and Poland. Geol. Mag. 149, 308e332. Paleontology, vol. 2. Columbia University Press, New York, Pienkowski, G., Niedzwiedzki, G., Branski, P., 2014. Climatic pp. 314e368. reversals related to the Central Atlantic magmatic province Olsen, P.E., Sues, H.-D., 1986. Correlation of continental Late caued the end-Triassic biotic crisisdevidence from Triassic and Early Jurassic sediments, and patterns of the continental strata in Poland. Geol. Soc. Am. Spec. Pap. 505, Triassic-Jurassic tetrapod transition. In: Padian, K. (Ed.), The 263e286. journal of palaeogeography 4 (2015) 331e348 347

Pott, C., McLoughlin, S., 2009. Bennettitalean foliage in the Pennsylvania: Reassessment of stratigraphic ranges. N. M. Rhaetian-Bajocian (latest Triassic-middle Jurassic) ﬂoras of Mus. Nat. Hist. Sci. Bull. 3, 439e445. Scania, southern Sweden. Rev. Palaeobot. Palynol. 158, Simms, M.J., Ruffell, A.H., 1989. Synchroneity of climatic change 117e166. and extinctions in the Late Triassic. Geology 17, 265e268. Rainforth, E.C., 2003. Revision and re-evaluation of the Early Simms, M.J., Ruffell, A.H., 1990. Climatic and biotic change in the Jurassic dinosaurian ichnogenus. Otozoum. Palaeontol. 46, Late Triassic. J. Geol. Soc. Lond. 147, 321e327. 803e838. Smith, R.M.H., Marsicano, C.A., Wilson, J.A., 2009. Sedimentology Ramezani, J., Bowring, S.A., Pringle, M., Winslow III, F.D., and paleoecology of a diverse Early Jurassic tetrapod tracksite Rasbury, E.T., 2005. The Manicouagan impact melt rock: a in Lesotho, southern Africa. Palaios 24, 672e684. proposed standard for intercalibration of U-Pb and 40Ar/39/Ar Spielmann, J.A., Lucas, S.G., Hunt, A.P., 2013. The ﬁrst Norian isotopic systems. In: 15th V. M. Goldschmidt Conference (Revueltian) rhynchosaur: bull Canyon formation, New Abstract, vol. A321. Mexico, U. S. A. N. M. Mus. Nat. Hist. Sci. Bull. 61, 562e566. Rigo, M., Preto, N., Roghi, G., Tateo, F., Mietto, P., 2007. A rise in Steinthorsdottir, M., Jeram, A.J., McElwain, J.C., 2011. Extremely

the carbonate compensation depth of western Tethys in the elevated CO2 concentrations at the Triassic/Jurassic boundary. Carnian (Late Triassic): deep-water evidence for the Carnian Palaeogeogr. Palaeoclimatol. Palaeoecol. 308, 418e432. pluvial event. Palaeogeogr. Palaeoclimatol. Palaeoecol. 246, Stocker, M.R., Butler, R.J., 2013. Phytosauria. In: Nesbitt, S.J., 188e205. Desojo, J.B., Irmis, R.B. (Eds.), Anatomy, Phylogeny and Ruckwied, K., Gotz,€ A.E., Palfy, J., Tor€ ok,€ A., 2008. Palynology of a Palaeobiology of Early Archosaurs and their Kin, Special terrestrial coal-bearing series across the Triassic/Jurassic Publications, 379. Geological Society, London, pp. 91e118. boundary (Mecsek Mts, Hungary). Cent. Eur. Geol. 51, 1e15. Sues, H.-D., Olsen, P.E., 2015. Stratigraphic and temporal context Ruhl, M., Veld, H., Kuerschner, W.M., 2010. Sedimentary organic and faunal diversity of Permian-Jurassic continental tetrapod matter characterization of the Triassic-Jurassic boundary assemblages from the Fundy rift basin, eastern Canada. Atl. GSSP at Kuhjoch (Austria). Earth Planet. Sci. Lett. 292, 17e26. Geol. 51, 139e205. Schafer,€ P., Fois, E., 1987. Systematics and evolution of Triassic Szajna, M.J., Silvestri, S.M., 1996. A new occurrence of the Bryozoa. Geol. Palaeontol. 21, 173e225. ichnogenus Brachychirotherium: Implications for the Triassic- Schaller, E.M., Wright, J.D., Kent, D.V., Olsen, P.E., 2012. Rapid Jurassic mass extinction event. Mus. North. Ariz. Bull. 60, emplacement of the Central Atlantic Magmatic Province as 275e283. e e net sink for CO2. Earth Planet. Sci. Lett. 323 324, 27 39. Szulc, J., Racki, G., Srodon, J., Lucas, S.G., 2015. Norian age of the Schoch, R.R., Milner, A.R., 2000. Stereospondyli. Encycl. Lipie Sla˛skie vertebrate fauna explains its alleged oddity. Acta Paleoherpetol. 3B, 1e203. Palaeontol. Pol. (in press). Schoene, B., Guex, J., Bartolini, A., Schaltegger, U., Blackburn, T.J., Tanner, L.H., Hubert, J.F., Coffey, B.P., McInerney, D.P., 2001.

2010. Correlating the end-Triassic mass extinction and flood Stability of atmospheric CO2 levels across the Triassic/Jurassic basalt volcanism at the 100 ka level. Geology 38, 387e390. boundary. Nature 411, 675e677. van de Schootbrugge, B., Quan, T., Lindstrom,€ S., Pu¨ ttmann, W., Tanner, L.H., Lucas, S.G., Chapman, M.G., 2004. Assessing the Heunisch, C., Pross, J., Fiebig, J., Petschick, R., Rohling,€ H.-G., record and causes of Late Triassic extinctions. Earth Sci. Rev. Richoz, S., Rosenthal, Y., Falkowski, P.G., 2009. Floral changes 65, 103e139. across the Triassic/Jurassic boundary linked to flood basalt Tanner, L.H., Smith, D.L., Allan, A., 2007. Stomatal response of e volcanism. Nat. Geosci. 2, 589 594. swordfern to volcanogenic CO2 and SO2 from Kilauea volcano, Schuurman, W.M.L., 1979. Aspects of Late Triassic palynology. 3. Hawaii. Geophys. Res. Lett. 34, L15807. http://dx.doi.org/ Palynology of latest Triassic and earliest Jurassic deposits of 10.1029/2007GL030320. the northern limestone Alps in Austria and southern Thulborn, T., Turner, S., 2003. The last dicynodont: an Australian Germany, with special reference to a palynological Cretaceous relict. Proc. R. Soc. Lond. B 270, 985e993. characterization of the Rhaetian stage in Europe. Rev. Traverse, A., 1988. Plant evolution dances to a different beat. Hist. Palaeobot. Palynol. 27, 53e75. Biol. 1, 277e301. Sepkoski Jr., J.J., 1982. Mass extinctions in the de Valais, S., 2009. Ichnotaxonomic revision of Ameghinichnus,a Phanerozoic oceans: a review. Geol. Soc. Am. Spec. Pap. 190, mammalian ichnogenus from the middle Jurassic La Matilde 283e289. formation, Santa Cruz province, Argentina. Zootaxa 2203, Sha, J., Vajda, V., Pan, Y., Larsson, L., Yao, X., Zhang, X., Wang, Y., 1e21. Cheng, X., Jiang, B., Deng, S., Chen, S., Peng, B., 2011. Visscher, H., Van Houte, M., Brugman, W.A., Poort, R.J., 1994. Stratigraphy of the Triassic-Jurassic boundary successions of Rejection of a Carnian (late Triassic) “pluvial event” in Europe. the southern margin of the Junggar basin, northwestern Rev. Palaeobot. Palynol. 83, 217e226. China. Acta Geol. Sin. 85, 421e436. Weems, R.E., 1992. The “terminal Triassic catastrophic extinction Sha, J., Olsen, P.E., Pan, Y., Xu, D., Wang, Y., Zhang, X., Yao, X., event” in perspective: a review of Carboniferous through Early Vajda, V., 2015. Triassic-Jurassic climate in continental high- Jurassic terrestrial vertebrate extinction patterns. Palaeogeogr. latitude Asia was dominated by obliquity-paced variations Palaeoclimatol. Palaeoecol. 94, 1e29. (Junggar Basin, U¨ ru¨ mqi, China). Proc. Natl. Acad. Sci. 112, Weems, R.E., Lucas, S.G., 2015. A revision of the Norian 3624e3629. conchostracan zonation in North America and its implications Shubin, N.H., Olsen, P.E., Sues, H.-D., 1994. Early Jurassic small for Late Triassic North American tectonic history. N. M. Mus. tetrapods from the McCoy Brook formation of Nova Scotia, Nat. Hist. Sci. Bull. 67, 303e317. Canada. In: Fraser, N.C., Sues, H.-D. (Eds.), In the Shadow of Whiteside, J.H., Olsen, P.E., Kent, D.V., Fowell, S.J., Et- the Dinosaurs. Cambridge University Press, Cambridge, Touhami, M., 2007. Synchrony between the Central Atlantic pp. 242e250. magmatic province and the Triassic-Jurassic mass-extinction Sigurdsson, H., 1990. Assessment of atmospheric impact event? Palaeogeogr. Palaeoclimatol. Palaeoecol. 244, 345e367. of volcanic eruptions. Geol. Soc. Am. Spec. Pap. 247, 99e110. Whiteside, J.H., Olsen, P.E., Eglinton, T., Brookfield, M.E., Silvestri, S.M., Szajna, M.J., 1993. Biostratigraphy of vertebrate Sambrotto, R.N., 2010. Compound-specific carbon isotopes footprints in the Late Triassic section of the Newark Basin, from Earth's largest flood basalt eruptions directly linked to 348 journal of palaeogeography 4 (2015) 331e348

the end-Triassic mass extinction. Proc. Natl. Acad. Sci. U. S. A. high-precision U-Pb geochronology constraints on the 107, 6721e6725. duration of the Rhaetian. Geology 42, 571e574. Wotzlaw, J.-F., Guex, J., Bartolini, A., Gallet, Y., Krystyn, L., Yapp, C.J., Poths, H., 1996. Carbon isotopes in continental McRoberts, C.A., Taylor, D., Schoene, B., Schaltegger, U., 2014. weathering environments and variations in ancient e Towards accurate numerical calibration of the Late Triassic: atmospheric CO2 pressure. Earth Planet. Sci. Lett. 137, 71 82.