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The end-Jurassic extinction
Consideration of the end-Jurassic extinction should start with a brief introduction to the Jurassic–Cretaceous (J–K) boundary problem. The single-system J–K boundary is still not defined by a global boundary stratotype section and point (GSSP). As of 2012, the section and key events were under discussion.
In the middle of the nineteenth century, scientists placed the J–K boundary at the boundary between the marine Portlandian and the non-marine Purbeckian stages (or the marine Neocomian in the Alps; see Wimbledon 2008). Later, after the introduction of the Valanginian and Berriasian stages in the lowermost Cretaceous, the J–K boundary was set at the base of the Berriasian or Valanginian stages. In the higher latitudes this boundary was traditionally placed between the Volgian and Ryazanian (the Boreal Berriasian) stages. Over the course of the late twentieth and early twenty-first centuries, the correlation of the Upper Volgian and Lower Berriasian, albeit based on indirect evidence, became accepted widely (Zeiss 1983; Sey and Kalacheva 1999; among others). For example, this correlation was used in databases, such as
the Compendium of Fossil Marine Animal Genera (2002) by
J. John Sepkoski Jr.,and in numerous publications referencing the Paleobiology Database. Nevertheless, paleomagnetic data (Housa et al. 2007) along with new ammonite records from the Ryazanian of the Russian Platform (Mitta 2007; Mitta and Sha 2009) suggest that the Volgian more nearly corresponds to the Tithonian and that only the uppermost zone of the Volgian should be correlated with the lowermost Berriasian. It should be noted that the correlation of the Upper Volgian and Lower Berriasian superimposed Late Tithonian extinction rate likely resulted from a strong turnover in boreal molluscan faunas near to the Middle to Late Volgian transition and a decrease in Lower Berriasian origination rates.
Mass extinction at the J–K boundary was first recognized in a 1984 study by David M. Raup and Sepkoski on the basis of an analysis of ranges of marine invertebrate families. This conclusion was later confirmed at the genus level (Raup and Sepkoski 1986). The nature and significance of this extinction event have been controversial ever since.
When analyzing bivalve diversity through the Jurassic, Anthony Hallam concluded in a 1976 study that increase of the generic extinction rate at the end of the period correlated
with a regional marine regression. In studies in 1986 and 1989, Hallam contended that the end-Jurassic extinction in marine invertebrates had occurred on a regional, but not a global, scale. Only bivalves in Western Europe showed a high rate of species turnover within the Middle Volgian, whereas the brachiopods, foraminifera, and coccoliths showed no particularly marked change across the J–K boundary. Also, this extinction was observed only in those regions that showed a shallowing trend, whereas in areas characterized by end-Jurassic transgression the bivalve fauna showed no change upward in the sequence (Hallam 1986). The end-Jurassic extinction was later recognized in non-marine tetrapods (Benton 1995; Barrett and Upchurch 2005; Butler et al. 2011), marine vertebrates (Kriwet and Klug 2008; Benson et al. 2010 and references therein; Young et al. 2010), marine benthic organisms (Kiessling and Aberhan 2007a, 2007b), and radiolarians (Vishnevskaya and Basov 2007; Vishnevskaya and Kozlova 2012). Among boreal ammonites, a so-called Late Volgian crisis has been shown to have occurred (Mitta and Bogomolov 2007; Mitta and Sha 2009; Rogov et al. 2010), but in this case the J–K boundary does not coincide with any significant changes in ammonite faunas.
Some previously suggested Tithonian extinction events (e.g., the ichthyosaur extinction) now should be reappraised, because Tithonian ichthyosaur genera have been found in the Lower Cretaceous (Fischer et al. 2012). Other groups of marine reptiles (e.g., metriorhynchid crocodiles) show strong drops in diversity into the Early Tithonian (Young et al. 2010).
Hallam and Paul B. Wignall, in their 1997 book Mass
Extinctions and Their Aftermath, along with results published in
Biases in the data
There are different sources of bias inherent in J–K boundary paleodiversity studies. The end-Jurassic extinction exhibits a clear relation between the quantity of preserved sedimentary rock and taxonomic diversity (Smith and McGowan 2007). The strong influence of the European fossil record on global biodiversity curves should also be recognized from the good level of correspondence of the Mesozoic extinction events with fossil ranges derived from the French naturalist Alcide d’Orbigny’s publications of the mid-nineteenth century (see Ruban 2005). Additional problems with this extinction are related to the possible influence of the aforementioned Lagerstätten effect and commonly encoun-tered regressive facies in one of the most studied regions in Europe. Bias of database sources and problems with correla-tion (especially the boreal–Tethyan correlation) also affect the estimates of this extinction’s magnitude and scope. Nevertheless, generic richness curves, based on Sepkoski’s compendium of fossil marine genera and the Paleobiology
Database, compiled by Alexander V. Markov (2009) show a clear drop in diversity in the Early Berriasian for both the genera of mollusks and of all marine animals (see Figure 1). As is also indicated by the analysis of taxic first and last appearance datums, the Late Tithonian is characterized by peaks in appearance of new taxa and especially in extinction intensity (see Figure 2). In ammonites such high levels in both extinction and the origination rate reflect the existence of many short-lived taxa and a high rate of diversification.
Geological settings around the world
The Jurassic–Cretaceous boundary is characterized by a complex set of global and regional events that could be at least partially responsible for the observed biotic changes. There are three bolide impact events dated as occurring near to the Jurassic-Cretaceous transition. These are the Mjølnir impact, which occurred on the Barents Sea shelf (Dypvik et al. 2010); the Morokweng impact in South Africa (Reimold et al. 2002); and the Gosses Bluff impact in Australia (Haines 2005). The Mjølnir event is well dated by buchiid bivalves and ammonites and occurs very close to the Volgian–Ryazanian boundary. This event could be responsible for the rarity of occurrences of the Volgian–Ryazanian transitional beds in the Barents Sea shelf and Svalbard (Wierzbowski et al. 2011), but it is not
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Figure 1. Generic diversity. Reproduced by permission of Gale, a part of Cengage Learning.
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Figure 2. FAD and LAD of all marine genera (a) and molluscan genera (b) throughthe MiddleJurassic to latest Early Cretaceous, based onMarkov’s (2009) compilation of Sepkoski’s compendium and the Paleobiology Database.LateTithonian ismarkedbygreystripe. Reproducedbypermission of Gale, a part of Cengage Learning.
associated with any significant faunal changes except a distinct but short-term bloom of the prasinophycean alga Leiosphaer-idia, which has been recognized in post impact deposits (Dypvik et al. 2010).
Zircons recovered from the quartz norite of the Morokweng structure have yielded U–Pb ages of 1450.8 million years ago (MYA), and biotites have provided Ar–Ar ages of 1444 million years ago (Hart et al. 1997). These dates correspond approxi-mately to the base of the Cretaceous (Mahoney et al. 2005). The Australian Gosses Bluff crater has not been dated precisely. Soon after its identification it was dated as Early Cretaceous (1333 MYA; see Milton et al. 1972), but its age was later redetermined as earliest Cretaceous but close to the J–K boundary (142.50.8 MYA; see Haines 2005). The diameters of all these impact structures are relatively small: less than 50 miles (80 km) for the Morokweng structure, about 15 miles (24 km) for the Gosses Bluff crater, and 25 miles (40 km) for Mjølnir.
There are no unusually large global sea-level oscillations near the J–K boundary (Snedden and Liu 2010). The so-called Portland–Purbeck regression of northwestern Europe had a strong impact on the European fossil record (including the Russian Platform), but has been recognized as having been of limited regional extent. In addition to Europe, J–K boundary sea-level fall is recognized in the Kutch region of India (Bardhan et al. 2007). By contrast, there are many regions that show sea-level rises as having occurred during the J–K
transition (e.g., western Siberia, northern Siberia, Barents Sea, northeastern Asia, Far East, Gulf of Mexico, Himalayas).
Late Jurassic and earliest Cretaceous climates have been characterized as warm and equable. The Middle to Late Jurassic transition was marked by regional cooling in Europe (Wierzbowski and Rogov 2011), while the Late Jurassic showed gradual warming (Dera et al. 2011). Tithonian cooling, indicated by changes in bivalveδ18O values, is not recognized in isotope data derived from belemnite rostra (Dera et al. 2011). In boreal areas the whole Late Jurassic is characterized by a gradual increase in temperatures (Price and Rogov 2009; Žák et al. 2011), accompanied by aridization (Abbink et al. 2001). The beginning of high-latitude cooling at this time— recog-nized by the shift in δ18O values (Price et al. 2000), the appearance of tillites (Alley and Frakes 2003), and glendonite occurrences—might be correlated with the latest Berriasian/ latest Ryazanian to earliest Valanginian. Nevertheless, the significance of the oscillations inδ18O andδ13C values around the J–K boundary remains obscure (Föllmi 2012). In high-latitude sites, including many boreal areas, from the Norwegian Sea in the west to the Lena River Basin in the east, as well as in austral regions such as Antarctica and the Argentine Neuquén Basin, laminated organic-rich facies are very typical in the J–K transition (Föllmi 2012).
Paleoceanographic changes in the Tethys occurred in the Late Tithonian. During this time Ammonitico Rosso facies
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ckhardticeras”
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Ranges of ammonite genera
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Lemencia
Total amount of genera
FAD of genera LAD of genera
began to disappear, and the onset of pelagic white nannoconid-rich limestones with calpionellids have been dated to the same period (Cecca 1997). These changes coincided with a turnover in nannofossil assemblages: The “Conusphaera world” of the
Middle Tithonian changed to the“Nannoconusworld,” which
began in the Berriasian (Tremolada et al. 2006).
Ammonites case study
Ammonites are among the most intensively studied fossils from the J–K transition. Because this group is characterized by rapid evolution and occurrence in a wide spectrum of environments, it provides the most accurate biostratigraphic dating in comparison with other fossil groups. Even for Middle to Late Volgian transition beds, which show strong faunal provincialism, accurate zonal and infrazonal Panboreal correlations can be made by focusing on ammonites (Rogov and Zakharov 2009).
Latest Jurassic Tethyan ammonites are characterized by relatively high rates of diversification. Nearly half of Late Tithonian ammonite genera in Western Europe exhibit relatively small stratigraphic ranges (one or two zones). Such short-ranged genera were especially diverse within the upper-most two biozones of the Tithonian stage (see Figure 3). Thus,
there are many Late Tithonian ammonite genera (17 or half of the Late Tithonian genera) that never cross the Tithonian– Berriasian boundary; except for three genera, all ammonites disappear before the boundary horizon. Ammonite diversity in southwestern Europe grew constantly during the whole Late Tithonian (see Figure 3). Only one ammonite family disappears during the Late Tithonian. In contrast to the diversity pattern in Mediterranean and sub-Mediterranean ammonites, ammo-nites from the Panboreal Superrealm show a decrease in species richness during the latest Middle Volgian and the whole Late Volgian (see Figure 4). This decrease coincides with abrupt changes in ammonite morphology. In the Russian Platform, this event has been called the“Late Volgian crisis”(Mitta and
Bogomolov 2007; Mitta and Sha 2009) and is believed to have been related to sea-level fall. Sea-level regression has also been invoked as the primary extinction driver for latest Jurassic bivalves (Hallam 1986—but see Zakharov and Yanine 1975, a study showing the proximity of latest Jurassic and earliest Cretaceous bivalves in Siberia and the southern USSR on the generic level), neoselachian fishes (Kriwet and Klug 2008), and radiolarians (Vishnevskaya and Kozlova 2012). Nevertheless, analysis of boreal ammonite assemblages (see below) has revealed that the significant faunal changes encountered in those areas during the J–K transition are also associated with a continuous sea-level rise. Ranges of ammonite genera
Riasanites Total diversity per zone FAD of genera
Russian platform England Northern Siberia Spitsbergen
The uppermost Middle Volgian is characterized by remarkable changes in Boreal ammonite faunas. Large-sized and well-ribbed ammonites abruptly change to small-sized relatively smooth ammonites (see Figure 5) characterized by simplified sutures (see Figure 6). These changes were especially strong in England, where assemblages with
“Portlandian giants” are followed by those that include
small-sized Swinnertonia. Similar but more gradual changes have been recognized in other boreal areas.
In the Russian Platform the uppermost subzone of the
Epivirgatites nikitini zone is characterized by the
co-occur-rence of small-sized dorsoplanitids with early craspeditids belonging to two lineages (SubcraspeditesandKachpurites; see Rogov and Zakharov 2009). Dorsoplanitid ammonites disap-pear here at the end of the Middle Volgian. The same changes in ammonite faunas can be recognized in Svalbard (Rogov 2010; Wierzbowski et al. 2011). The same features, that is, a decrease in shell size, as well as a smoothness of ribbing, can be recognized in J–K ammonite faunas of northern Siberia.
The peak in ammonite richness and extinction in the latest Middle Volgian Epivirgatites nikitini zone (see Figure 4) corresponds partially to a very quick diversification in dorsoplanitid ammonites and partially to the strong paleo-biogeographical segregation. The maximum ammonite rich-ness from the single bed/biohorizon in the latest Middle Volgian does not exceed six genera. During the Middle to Late Volgian transition, ammonite diversity in the whole pan-boreal superrealm decreased significantly. Except for the uncommon records of phylloceratid and lytoceratid ammo-nites in northern Siberia (excluded from this analysis because of their persistent records through the whole Late Jurassic and Neocomian), ammonite diversity through the Late Volgian fluctuated from one to three genera.
Such low generic richness was accompanied by extremely low extinction and origination rates (see Figure 4). Only during the beginning portion of the Ryazanian was there marked diversification in craspeditid ammonites. At the same time ammonite diversity in the Russian Platform increased significantly due to mass immigration of Mediterranean berriasellid and himalayitid ammonites. The maximal size of Boreal ammonites also began to increase during the Early Ryazanian. The dorsoplanitid to craspeditid transition was marked by the independent appearance of ammonites with craspeditid morphologies within at least three semi-isolated basins: northwestern Europe, the Russian Platform, and the Arctic. Moreover, some characteristically craspeditid features (such as small size, smooth ribbing, and specific types of the septal suture) appeared mosaically within different dorsopla-nitid lineages during the Middle Volgian.
The causes of such complex changes in ammonite morphol-ogies remain unclear. These changes were more significant in those areas characterized by a sea-level fall, but have also been well recognized in other Boreal regions. Strong size reduction in Boreal ammonites in the latest Middle Volgian can be considered an example of the Lilliput effect, reflecting a pronounced ecological crisis. On the Russian Platform, new craspeditid taxa exhibit mass occurrences after the first phase of dorsoplanitid size reduction, forming bedding planes covered by hundreds of dwarfKachpuritesshells (1.2–2.0 inches [3–5 cm] in diameter). These changes in ammonite faunas partially coincide with an extinction event in Boreal bivalves, recognized in England (Hallam 1986) and caused by the sea-level fall. But analysis of the published data on bivalve and brachiopod ranges across the Middle and Upper Volgian of the Russian Platform (Gerasimov et al. 1995) shows only a minor turnover at the Figure 5. Typical large-sized and well-ribbed Middle Volgian dorsoplanitid
species level in bivalves accompanied by the extinction of only one brachiopod genus. Changes in belemnite faunas (e.g., the regional extinction of cylindroteuthid belemnites and the appearance of short-rostra Acroteuthis) are well recognized in northwestern Europe and the Russian Platform (Gustomesov 1964; Mutterlose 1990) but cannot be traced in Siberia (Dzyuba 2004). Perhaps changes in belemnite assemblages are connected directly with sea-level changes because they are observed only in regions showing clear evidence of sea-level fall.
In spite of the abrupt changes in ammonite morphologies, the end–Middle Volgian crisis exhibits some clear features of its own internal, biological nature, suggesting it was not caused directly by abiotic changes (e.g., increasing of speciation and extinction rates before the peak of the crisis, small-sized crisis fixed before the main crisis, the appearance of many short-ranged taxa near to the crisis event, changes in ecological dominants; see Kalandadze and Rautian 1993). The Late Volgian phase of the crisis is also characterized by the small magnitude of both extinction and origination rates and by very low species richnesses. The end of the Late Volgian is characterized by increasing extinction and origination rates in boreal ammonites and increasing generic richness (see Figure 4).
Changes in ammonite faunas clearly correspond to changes in radiolarians. As was shown in a 2012 study by Valentina S. Vishnevskaya and Genrietta E. Kozlova, specimens of
Figure 6. Craspeditid evolution during the latest Middle Volgian and Late Volgian. Zonal succession after Rogov, Zakharov, 2009, 2011. Craspeditid ammonites evolved independently within 3 semi-isolated basins (only cross-sections are shown): Swinnertonia, Subcraspedites, and Volgidiscus lineage mainly inhabited NW European region; Kachpurites and Garniericeras lineage was typical for the Russian Platform; while Craspedites (Craspedites), C. (Trautscholdiceras), and C. (Taimyroceras) lineages were widely distributed in Arctic. Reproduced by permission of Gale, a part of Cengage Learning.
Parvicingulafrom the Late Volgian are very small compared to their Middle Volgian counterparts, possess small pore frames, and have post-abdominal chambers with weakly developed circumferential ridges or almost none. Such simultaneous changes traced through the different areas of the pan-boreal superrealm in these two fossil groups could indicate that the crisis event was connected with changes in planktonic taxa and could reflect turnover in planktonic food webs. Similar size reductions in radiolarians have also been detected during other extinction events, such as the end-Permian extinction (De Wever et al. 2006). Such size decreases could be explained partly by warming because, at high temperatures, plankton may be able to offset some of the effects of reduced buoyancy caused by reduced water density and viscosity by reducing shell size (see Atkinson 1994). During Neogene climate changes, however, different microplankton groups showed different modes of shell size changes (Schmidt et al. 2006). Unfortunately, the diet of ammonites and the possible role of plankton in it are not well understood. Advances in the study of ammonoid paleobiology and feeding habitat (Kruta et al. 2011), based on the investigation of very specific heteromorph taxa, cannot be accepted as a valid model for other ammonites. As Marion Nixon pointed out in a 1996 contribution, the crop/stomach contents from the body chambers of ammo-nites show a wide spectrum of ammonite prey, ranging from other ammonites to crinoids, ostracods, and forami-nifers. Simultaneous species richness falls in Tethyan radiolarians (Vishnevskaya and Basov 2007), corresponding to nannoplankton turnover, partially overlapped with the size reduction of calpionellids at the base of the Berriasian.
Significance of the end-Jurassic extinction
event
In spite of its regional nature, the end-Jurassic extinction led to significant changes in at least some marine and terrestrial faunas. In the boreal seas this extinction event was
responsible for strong changes in ammonite assemblages. While pre-extinction ammonite diversity occurred during the earliest Cretaceous (Ryazanian), large Boreal ammonites appeared later. Other groups of Boreal animals crossed the J–K boundary without significant changes. The majority of marine groups show a drop in diversity only in those regions influenced by the sea-level fall during the Jurassic– Cretaceous transition. Paleoceanographic changes in the Tethys ocean led to changes in sedimentation, connected directly with bloom of new groups of microfossils with calcareous shells (especially calpionellids and nannoconids). These changes possibly led to a gradual increase in the diversity and abundance of plankton-feeding heteromorph ammonites during the Early Cretaceous. End-Jurassic extinction among the terrestrial faunas exerted an especially strong influence on sauropod dinosaurs. This could reflect an increase in predator activity on these specialized dinosaurs. Among the other groups of terrestrial biota, only minor changes in diversity and/or changes of dominant groups have been verified.
As was pointed out in 1997 by Hallam and Wignall, there is no evidence of a global mass extinction among the marine invertebrate fauna at or near to the Tithonian–Berriasian boundary. But there is good evidence, in Europe, of a regional event, significant only at the species level, among bivalves and a few other groups. In some cases this regional extinction in marine invertebrates (bivalves and belemnites of boreal Europe) is associated with a marine regression. The major turnover in Boreal ammonite faunas in the latest Middle Volgian and Late Volgian was perhaps amplified by sea-level oscillation, but its causes also quite possibly had a strong biological component, reflecting changes in the planktonic assemblages, especially changes in radiolarians. Tethyan ammonite faunas are characterized by relatively high speciation and extinction rates during the Tithonian, but the J–K boundary is not marked by any significant changes in the overall taxonomic makeup of these ammonites.
Resources
Books
Bardhan, Subhendu, Sabyasachi Shome, and Pinaki Roy. “Biogeography of Kutch Ammonites during the Latest Jurassic (Tithonian) and a Global Paleobiogeographic Over-view.”InCephalopods Present and Past: New Insights and Fresh Perspectives, edited by Neil H. Landman, Richard Arnold Davis, and Royal H. Mapes, 375–395. Dordrecht,
Netherlands: Springer, 2007.
Barrett, Paul M., and Paul Upchurch.“Sauropodomorph Diversity through Time: Paleoecological and Macro Evolu-tionary Implications.”InThe Sauropods: Evolution and Paleo-biology, edited by Kristina A. Curry Rogers and Jeffrey A. Wilson, 125–156. Berkeley: University of California Press,
2005.
Dypvik, Henning, Filippos Tsikalas, and Morten Smelror, eds. The Mjølnir Impact Event and Its Consequences: Geology and
Geophysics of a Late Jurassic/Early Cretaceous Marine Impact Event. Berlin: Springer, 2010.
Dzyuba, Oksana S.Belemnites (Cylindroteuthidae) and Biostratig-raphy of the Middle and Upper Jurassic of Siberia. [In Russian.] Novosibirsk, Russia: Publishing House of SB RAS, Depart-ment“Geo,”2004.
Gerasimov, Petr A., Vasily V. Mitta, and Maria D. Kochanova. Fossils of the Volgian Stage of Central Russia. [In Russian.] Moscow: VNIGNI, 1995.
Hallam, Anthony, and Paul B. Wignall.Mass Extinctions and Their Aftermath. Oxford: Oxford University Press, 1997.
Sepkoski, J. John, Jr. A Compendium of Fossil Marine Animal Genera. Bulletins of American Paleontology, no. 363. Ithaca, NY: Paleontological Research Institution, 2002.
Periodicals
Abbink, Oscar, Jordi Targarona, Henk Brinkhuis, and Henk Visscher.“Late Jurassic to Earliest Cretaceous Palaeoclimatic Evolution of the Southern North Sea.”Global and Planetary Change30, nos. 3–4 (2001): 231–256.
Alley, N.F., and L.A. Frakes.“First Known Cretaceous Glacia-tion: Livingston Tillite Member of the Cadna-owie Forma-tion, South Australia.”Australian Journal of Earth Sciences50, no. 2 (2003): 139–144.
Atkinson, D.“Temperature and Organism Size—a Biological Law for Ectotherms?”Advances in Ecological Research25 (1994): 1–58.
Benson, Roger B.J., Richard J. Butler, Johan Lindgren, and Adam S. Smith.“Mesozoic Marine Tetrapod Diversity: Mass Extinctions and Temporal Heterogeneity in Geological Megabiases Affecting Vertebrates.”Proceedings of the Royal SocietyB 277, no. 1683 (2010): 829–834.
Benton, M.J.“Diversification and Extinction in the History of Life.”Science268, no. 5207 (1995): 52–58.
Butler, Richard J., Roger B.J. Benson, Matthew T. Carrano, et al. “Sea Level, Dinosaur Diversity, and Sampling Biases: Investigating the‘Common Cause’Hypothesis in the
Ter-restrial Realm.”Proceedings of the Royal SocietyB 278, no. 1709 (2011): 1165–1170.
Cecca, Fabrizio.“Late Jurassic and Early Cretaceous Uncoiled Ammonites: Trophism-Related Evolutionary Processes.” Comptes Rendus de l’Académie des Sciences, series IIA,Earth and Planetary Science325, no. 8 (1997): 629–634.
Dera, Guillaume, Benjamin Brigaud, Fabrice Monna, et al. “Climatic Ups and Downs in a Disturbed Jurassic World.” Geology39, no. 3 (2011): 215–218.
De Wever, Patrick, Luis O’Dogherty, andŠpela Gorican.“The Plankton Turnover at the Permo-Triassic Boundary, Em-phasis on Radiolarians.”Eclogae geologicae Helvetiae99, supp. 1 (2006): S49–S62.
Fischer, Valentin, Michael W. Maisch, Darren Naish, et al.“New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary.”PLoS ONE7, no. 1 (2012): e29234.
Föllmi, K.B.“Early Cretaceous Life, Climate, and Anoxia.” Cretaceous Research35 (2012): 230–257.
Gustomesov, V.A.“Boreal Late Jurassic Belemnites (Cylindro-teuthinae) of the Russian Platform.”[In Russian.]Transactions of the Geological Institute107 (1964): 89–216.
Haines, P.W.“Impact Cratering and Distal Ejecta: The Australian Record.”Australian Journal of Earth Sciences52, nos. 4–5 (2005): 481–507.
Hallam, Anthony.“Stratigraphic Distribution and Ecology of European Jurassic Bivalves.”Lethaia9, no. 3 (1976): 245–259.
Hallam, Anthony.“The Pliensbachian and Tithonian Extinction Events.”Nature319, no. 6056 (1986): 765–768.
Hallam, Anthony.“The Case for Sea-Level Change as a Dominant Causal Factor in Mass Extinction of Marine
Invertebrates.”Philosophical Transactions of the Royal Society B 325, no. 1228 (1989): 437–455.
Hart, Rodger J., Marco A.G. Andreoli, Marian Tredoux, et al. “Late Jurassic Age for the Morokweng Impact Structure, Southern Africa.”Earth and Planetary Science Letters147, nos. 1–4 (1997): 25–35.
Housa, Václav, Petr Pruner, Victor A. Zakharov, et al.“Boreal–
Tethyan Correlation of the Jurassic–Cretaceous Boundary
Interval by Magneto- and Biostratigraphy.”Stratigraphy and Geological Correlation15, no. 3 (2007): 297–309.
Kalandadze, Nikolai N., and Alexander S. Rautian.
“Symptomatology of Ecological Crises.”Stratigraphy and Geological Correlation1 (1993): 473–478.
Kiessling, Wolfgang, and Martin Aberhan.“Environmental Determinants of Marine Benthic Biodiversity Dynamics through Triassic–Jurassic Time.”Paleobiology33, no. 3 (2007a): 414–434.
Kiessling, Wolfgang, and Martin Aberhan.“Geographical Distribution and Extinction Risk: Lessons from Triassic–
Jurassic Marine Benthic Organisms.”Journal of Biogeography 34, no. 9 (2007b): 1473–1489.
Kriwet, Jürgen, and Stefanie Klug.“Diversity and Biogeography Patterns of Late Jurassic Neoselachians (Chondrichthyes, Elasmobranchii).”Geological Society, London, Special Publications 295 (2008): 55–69.
Kruta, Isabelle, Neil H. Landman, Isabelle Rouget, et al.“The Role of Ammonites in the Mesozoic Marine Food Web Revealed by Jaw Preservation.”Science331, no. 6013 (2011): 70–72.
Mahoney, J.J., R.A. Duncan, M.L.G. Tejada, et al.“Jurassic–
Cretaceous Boundary Age and Mid-Ocean-Ridge–Type Mantle Source for Shatsky Rise.”Geology33, no. 3 (2005): 185–188.
Markov, Alexander V.“Alpha Diversity of Phanerozoic Marine Communities Positively Correlates with Longevity of Gen-era.”Paleobiology35, no. 2 (2009): 231–250.
Mikhailov, Nikolai P.“Pavlovia and Allied Groups of Ammonites.”[In Russian.]Bulletin of the Moscow Society of Naturalists, Geology Section37, no. 6 (1962): 3–30.
Milton, D.J., B.C. Barlow, Robin Brett, et al.“Gosses Bluff Impact Structure, Australia.”Science175, no. 4027 (1972): 1199–1207.
Mitta, Vasily V.“Ammonite Assemblages from Basal Layers of the Ryazanian Stage (Lower Cretaceous) of Central Russia.” Stratigraphy and Geological Correlation15, no. 2 (2007): 193–205.
Mitta, Vasily V., and Yuri I. Bogomolov.“Late Jurassic of the Russian Platform: Ammonite Evolution and
Paleoenvironments.”Bulletin of the Geological Society of Greece 40 (2007): 1485–1490.
Mitta, Vasily V., and JinGeng Sha.“Late Jurassic Ammonite Evolution and Paleoenvironment of the Russian Platform.” Science in China, series D,Earth Sciences52, no. 12 (2009): 2024–2028.
Mutterlose, Jörg.“A Belemnite Scale for the Lower Cretaceous.” Cretaceous Research11, no. 1 (1990): 1–15.
Platform.”Palaeogeography, Palaeoclimatology, Palaeoecology273, nos. 1–2 (2009): 41–49.
Price, Gregory D., Alastair H. Ruffell, Charles E. Jones, et al. “Isotopic Evidence for Temperature Variation during the Early Cretaceous (Late Ryazanian–Mid-Hauterivian).” Journal of the Geological Society157, no. 2 (2000): 335–343.
Raup, David M., and J. John Sepkoski Jr.“Periodicity of Extinctions in the Geologic Past.”Proceedings of the National Academy of Sciences of the United States of America81, no. 3 (1984): 801–805.
Raup, David M., and J. John Sepkoski Jr.“Periodic Extinction of Families and Genera.”Science231, no. 4740 (1986): 833–836.
Reimold, Wolf Uwe, Richard A. Armstrong, and Christian Koeberl.“A Deep Drillcore from the Morokweng Impact Structure, South Africa: Petrography, Geochemistry, and Constraints on the Crater Size.”Earth and Planetary Science Letters201, no. 1 (2002): 221–232.
Rogov, Mikhail A.“New Data on Ammonites and Stratigraphy of the Volgian Stage in Spitzbergen.”Stratigraphy and Geological Correlation18, no. 5 (2010): 505–531.
Rogov, Mikhail A., and Victor A. Zakharov.“Ammonite- and Bivalve-Based Biostratigraphy and Panboreal Correlation of the Volgian Stage.”Science in China, series D,Earth Sciences 52, no. 12 (2009): 1890–1909.
Rogov, Mikhail A., Victor A. Zakharov, and Boris L. Nikitenko. “The Jurassic–Cretaceous Boundary Problem and the Myth
on J/K Boundary Extinction.”Earth Science Frontiers17 (2010): 13–14.
Ruban, Dmitry A.“Mesozoic Marine Fossil Diversity and Mass Extinctions: An Experience with the Middle XIX Century Paleontological Data.”Revue de Paléobiologie, Genève24, no. 1 (2005): 287–290.
Schmidt, Daniela N., David Lazarus, Jeremy R. Young, and Michal Kucera.“Biogeography and Evolution of Body Size in Marine Plankton.”Earth-Science Reviews78, nos. 3–4 (2006):
239–266.
Sey, Irina I., and Elena D. Kalacheva.“Lower Berriasian of Southern Primorye (Far East Russia) and the Problem of Boreal–Tethyan Correlation.”Palaeogeography, Palaeoclimatol-ogy, Palaeoecology150, nos. 1–2 (1999): 49–63.
Smith, Andrew B., and Alistair J. McGowan.“The Shape of the Phanerozoic Marine Palaeodiversity Curve: How Much Can Be Predicted from the Sedimentary Rock Record of Western Europe?”Palaeontology50, no. 4 (2007): 765–774.
Snedden, John W., and Chengjie Liu.“A Compilation of Phanerozoic Sea-Level Change, Coastal Onlaps, and Recom-mended Sequence Designations.”Search and Discovery, article 40594 (2010). Accessed July 22, 2012. http://www.searchand-discovery.com/documents/2010/40594snedden/ndx_snedden. pdf.
Spath, Leonard Frank.“Additional Observations on the Inver-tebrates (Chiefly Ammonites) of the Jurassic and Cretaceous
of East Greenland. I. The Hectoroceras Fauna of the S.W. Jameson Land.”Meddelelser om Grønland132, no. 3 (1947): 1–69.
Tremolada, Fabrizio, André Bornemann, Timothy J. Bralower, et al.“Paleoceanographic Changes across the Jurassic/Creta-ceous Boundary: The Calcareous Phytoplankton Response.” Earth and Planetary Science Letters241, nos. 3–4 (2006): 361–371.
Vishnevskaya, Valentina S., and Ivan A. Basov.“New Data on Biotic Events during the Santonian–Campanian Transition: Evidence from Microplankton Fossils of the Russian Pacific Margin.”Doklady Earth Sciences417, no. 2 (2007): 1299–1303. Vishnevskaya, Valentina S., and Genrietta E. Kozlova.“Volgian and Santonian–Campanian Radiolarian Events of the Russian Arctic and Pacific Rim.”Acta Palaeontologica Polonica. 57, no. 4 (2012): 773–790.
Wierzbowski, Andrzej, Krzysztof Hryniewicz, Øyvind Hammer, et al.“Ammonites from Hydrocarbon Seep Carbonate Bodies from the Uppermost Jurassic–Lowermost Cretaceous of Spitsbergen and Their Biostratigraphical Importance.”Neues Jahrbuch für Geologie und Paläontologie: Abhandlungen262, no. 3 (2011): 267–288.
Wierzbowski, Hubert, and Mikhail A. Rogov.“Reconstructing the Palaeoenvironment of the Middle Russian Sea during the Middle–Late Jurassic Transition Using Stable Isotope Ratios
of Cephalopod Shells and Variations in Faunal Assemblages.” Palaeogeography, Palaeoclimatology, Palaeoecology299, nos. 1–2
(2011): 250–264.
Wimbledon, William A.P.“The Jurassic–Cretaceous Boundary:
An Age-Old Correlative Enigma.”Episodes31, no. 4 (2008): 423–428.
Young, Mark T., Stephen L. Brusatte, Marcello Ruta, and Marco Brandalise de Andrade.“The Evolution of Metriorhynchoidea (Mesoeucrocodylia, Thalattosuchia): An Integrated Approach Using Geometric Morphometrics, Analysis of Disparity, and Biomechanics.”Zoological Journal of the Linnean Society158, no. 4 (2010): 801–859.
Žák, Karel, Martin Kosták, Otakar Man, et al.“Comparison of Carbonate C and O Stable Isotope Records across the Jurassic/Cretaceous Boundary in the Tethyan and Boreal Realms.”Palaeogeography, Palaeoclimatology, Palaeoecology299, nos. 1–2 (2011): 83–96.
Zakharov, Victor A., and Boris T. Yanine.“Les bivalves à la fin du Jurassique et au début du Crétacé.”Mémoires du Bureau des Recherches Géologiques et Minières86 (1975): 221–228.
Zeiss, Arnold.“Zur Frage der Äquivalenz der Stufen Tithon/ Berrias/Wolga/Portland in Eurasien und Amerika: Ein Bietrag zur Klärung der weltweuten Korrelation der Jura-/Kreide-Grenzschichten im marinen Bereich.”Zitteliana10 (1983): 427–438.
