Triassic Officially Loses Status as the First Period of the Age of Dinosaurs Because it Just Doesn't Have Many

The International Stratigraphic Council (ISC) announced today that it was stripping the Triassic Period of the privilege of representing the first period of the Mesozoic Era, otherwise known as the Age of Dinosaurs.

ISC Chairman Dr. Waldo Weatherbee stated that this decision was made based on the general paucity of Triassic dinosaurs. "Let's face it," he said, "Current research is demonstrating that many of the things in the Triassic we thought were dinosaurs are turning out to be all kinds of other types of critters, and the things that are still dinosaurs simply aren't that impressive."

Council member Dr. Geraldine Grundy agreed. "I'm sick and tired of paleontologists turning up little crumbly bits of bone from the Triassic and claiming these are the earliest dinosaurs. Give me a break. Show me some real bones!"

Asked about Coelophysis and Plateosaurus, Grundy plugged her ears and yelled "blah, blah, blah, I can't hear you!"

University of Riverdale paleontology graduate student Reggie Mantle argues, "the Triassic is lame man, there are no cool dinos such as raptors, longnecks, and T-rex.  At least the Jurassic has some cool movies made about it, what does the Triassic have? Triassic Attack? How completely lame!"

Fellow student Betty Cooper also agrees, "I can't even pronounce Chromigo-what ever you call it. Dinosaurs should only have easy names like Stegosaurus and Triceratops. Plus, now they tell us that the only cool Triassic dinosaur Eoraptor isn't even a raptor?! Why would anyone study this crap?"

The council voted 312 to 2 to officially dissolve the Triassic and reassign what was  the later part of the Late Triassic to the Jurassic (and thus to the beginning of the Mesozoic), and the Early, Middle and beginning of the Late Triassic epochs to the Permian.

Professor Flutesnoot, a noted dinosaur researcher from the Society for Dinosaur Dominance supports these reassignments. "Removal of the Triassic as a valid period of the Mesozoic solves the missing Triassic dinosaur problem that is currently recognized, especially regarding the lack of bonafide ornithischian dinosaurs from that period. Dinosaurs now first appear neatly in the Jurassic and clearly define the lower boundary of that period. Many of us will sleep better tonight knowing that this problem has been solved."

Weatherbee added "You simply can't be part of the Age of Dinosaurs without any bleedin' dinosaurs!"

"This is exactly how things should be," chimed in Grundy, "keep your non-dinosaur bearing units out of the Mesozoic!".

The council also voted 312 to 2 to combine and rename all of the eras prior to the Mesozoic as the Predinozoic and in a subsequent vote of 312 to 0 kicked out their two dissenting members.

"We don't need these bleedin' heart liberal Triassophiles messing up our wonderful timescale and relegating dinosaurs to 2nd class organisms against the desires of our founding fathers", explained Weatherbee.

As of press time the International Subcommision on the Triassic simply stated that they could not possibly think of any intelligent response whatsoever.

Revised timescale by the ISC (modified from here)

More Evidence for Long Norian and Rhaetian Stages

This is a new paper looking at Triassic magnetostratigraphic correlations between Europe and North America.  The findings essentially support the early conclusions of Muttoni et al. (2004; 2010) arguing for long Norian and Rhaetian stages.  Correlations between the Steinbergkogel sections in Austria and the Newark Supergroup in the eastern U.S.A., suggest the following timescale revisions:

Carnian-Norian boundary: ~226.6 Ma;
Lacian-Alaunian boundary: ~216.4 Ma (fairly equivalent to the old Carnian/Norian boundary);
Alaunian-Sevatian 1 boundary: 211.8 Ma;
Norian Rhaetian boundary: ~209.8 Ma.

Thus according to these data the early Norian is approximately 10 million years long, the middle Norian is 4.5 million years old, and the late Norian is 2 million years old for an approximately 17 million year long Norian stage.  The Rhaetian is approximately 9 million years long.

Proposed biostratigraphic data from palynomorphs and conchostracans suggesting a shorter Norian are refuted.

Hüsing, S. K., Deenen, M. H. L., Koopmans, J. G., and W. Krijgsman. 2011. Magnetostratigraphic dating of the proposed Rhaetian GSSP at Steinbergkogel (Upper Triassic, Austria): Implications for the Late Triassic time scale.  Earth and Planetary Science Letters 302: 203-216

Abstract - The Global Stratotype Section and Point (GSSP) for the Rhaetian Stage has recently been proposed at Steinbergkogel in Austria. We re-sampled the Steinbergkogel sections (STK-A and STK-B + C) in high-resolution to establish a robust magnetostratigraphy that allows global correlation. The palaeomagnetic signal at Steinbergkogel is composed of three components, which can be separated by thermal demagnetization. The highest temperature component, revealed between 280/300 and maximum 600 °C is of dual polarity and is interpreted as primary. Rock magnetic experiments showed that the signal is carried by magnetite. Our results allow correlation between the two individual Steinbergkogel outcrops. Subsequently, we correlate the two key biostratigraphic horizons for the base of the Rhaetian, the FO of M. hernsteini and the FAD of M. posthernsteini to other sections of the Tethys domain. The correlation to the astronomically dated continental successions of the Newark basin indicates that these positions for the base of the Rhaetian are most likely determined in chrons E16n and E16r, respectively. This correlation is confirmed by cyclostratigraphic control on the marine Pizzo Mondello (Italy) section, where a combination of long period Milankovitch cycles (~ 175-Myr) and short-eccentricity cycles (~ 100-kyr) provide additional correlation constraints, respectively supporting a long duration of the Rhaetian. Our study implies that the Norian and Rhaetian Stages have durations of ~ 17 and ~ 9 Myr.


REFERENCES

Muttoni, G., Kent, D.V., Jadoul, F., Olsen, P.E., Rigo, M., Galli, M.T., and A. Nicora. 2010. Rhaetian magneto-biostratigraphy from the Southern Alps (Italy): constraints on Triassic chronology. Palaeogeography, Palaeoclimatology, Palaeoecology 285: 1–16.

Muttoni, G., Kent, D.V., Olsen, P.E., Di Stefano, P., Lowrie, W., Bernasconi, S.M., and F. M. Hernandez. 2004. Tethyan magnetostratigraphy from Pizzo Mondello (Sicily)and correlation to the Late Triassic Newark astrochronological polarity time scale. Geological Society of America Bulletin 116: 1043–1058.

New Book Available - The Triassic Timescale

Available now, Geological Society of London Special Publication 334, The Triassic Timescale, edited by S. G. Lucas.  The table of contents is listed below and you can find out more about the book and order it here.  The PDF of the introductory article is also available as a free download.  Note that in this introductory article Lucas rejects the recent long Norian hypothesis basing this rejection on vertebrate, pollen, and conchostracan biochronology.  For a detailed discussion of this I'll refer interested parties again to the recent paper by Irmis et al. (2010).

LUCAS, S. G. The Triassic timescale: an introduction.

LUCAS, S. G. The Triassic chronostratigraphic scale: history and status.

MUNDIL, R., PÁLFY, J., RENNE, P. R. & BRACK, P. The Triassic timescale: new constraints and a review of geochronological data.

HOUNSLOW, M. W. &MUTTONI, G. The geomagnetic polarity timescale for the Triassic: linkage to stage boundary definitions.

TANNER, L. H. The Triassic isotope record.

TANNER, L. H. Cyclostratigraphic record of the Triassic: a critical examination.

ORCHARD, M. J. Triassic conodonts and their role in stage boundary definition.

O’DOGHERTY, L., CARTER, E. S., GORIČAN, Š., & DUMITRICA, P. Triassic radiolarian biostratigraphy.

MCROBERTS, C. A. Biochronology of Triassic bivalves.

BALINI, M., LUCAS, S. G., JENKS, J. F. & SPIELMANN, J. A. Triassic ammonoid biostratigraphy: an overview.

KÜRSCHNER, W. M. & WALDEMAAR HERNGREEN, G. F. Triassic palynology of central and northwestern Europe: a review of palynofloral diversity patterns and biostratigraphic subdivisions.

CIRILLI, S. Upper Triassic–lowermost Jurassic palynology and palynostratigraphy: a review.

KOZUR, H. W. & WEEMS, R. E. The biostratigraphic importance of conchostracans in the continental Triassic of the northern hemisphere.

KLEIN, H. & LUCAS, S. G. Tetrapod footprints – their use in biostratigraphy and biochronology of the Triassic.

LUCAS, S. G. The Triassic timescale based on nonmarine tetrapod biostratigraphy and biochronology.

New Biostratigraphical Constraints for the Norian⁄Rhaetian Boundary

Once even questioned as a valid stage the Rhaetian has made quite a comeback research-wise, especially since the GSSP for the Norian/Rhaetian boundary has yet to be determined.

Giordano, N., Rigo, M., Ciarapica G. & Bertinelli A. 2010. New biostratigraphical constraints for the Norian ⁄Rhaetian boundary: data from Lagonegro Basin, Southern Apennines, Italy. Lethaia, 10.1111/j.1502-3931.2010.00219.x.

Abstract - Four stratigraphic sections belonging to Lagonegro succession (Southern Apennines) at Mt S. Enoc, Pignola-Abriola, Sasso di Castalda and Mt Volturino have been studied in detail under to provide a new micro-palaeontological data set based on conodonts and radiolarians for the characterization of the Norian ⁄Rhaetian interval. The studied sections represent the different settings of the Lagonegro Basin (from proximal to distal facies) and permit a detailed, integrated, biostratigraphy of the Calcari con Selce (cherty limestones) and Scisti Silicei formations (bedded cherts with radiolarians) to be drawn up. The upper portion of the Calcari con Selce Formation, exhibits intermediate characteristics between the Calcari con Selce and Scisti Silicei Formation, in particular the progressive decrease in carbonate content against an increase in shales and cherts. Within the four sections studied, the Norian ⁄Rhaetian interval has been documented both with conodonts and radiolarians. Because of the continuity and the absence of condensed facies, it has been possible to recognize the morphocline between species Misikella hernsteini and Misikella posthernsteini, here represented by all the transitional forms characterized by common features between the two species, gathered in three evolutionary steps. Moreover, the morphocline between M. hernsteini and M. posthernsteini has been involved in the definition of the Norian ⁄ Rhaetian Boundary, recognizing thus the FAD of M. posthernsteini, one of the possible biomarkers proposed for the boundary. The rich, well-preserved, radiolarian associations of Pignola-Abriola, Sasso di Castalda and Mt Volturino permit the correlation of Tethyan and American conodont successions, highlighting the importance of the mostly coincident occurrences of M. posthernsteini and Epigondolella mosheri morphotype A, which correspond to the base of Proparvicingula moniliformis A. Z. and the disappearance of bivalve Monotis. These coincident bioevents are used here to define the base of the Rhaetian stage.

Rhaetian Magneto-biostratigraphy from the Southern Alps (Italy): Constraints on Triassic Chronology

This is fairly significant as it argues for quite a long Rhaetian Stage of the latest Triassic. If this is correct it means that a sizable portion of the upper part of the Chinle Formation could actually be Rhaetian in age. Not bad considering not too long ago workers were arguing if the Rhaetian was really even applicable outside of the marine realm.

Muttoni, G., Kent, D.V., Jadoul, F., Olsen, P.E., Rigo, M., Galli, M.T., and A. Nicora. 2009. Rhaetian magneto-biostratigraphy from the Southern Alps (Italy): Constraints on Triassic chronology. Palaeogeography, Palaeoclimatology, Palaeoecology. doi: 10.1016/j.palaeo.2009.10.014.

ABSTRACT: New Late Triassic-earliest Jurassic magneto-biostratigraphic data have been obtained from three overlapping sections in the Southern Alps, Italy (Costa Imagna, Brumano, Italcementi Quarry), comprised of ~ 520 m of shallow marine carbonates outcropping in stratigraphic continuity. Characteristic magnetic components of presumed depositional age record a sequence of 9 normal and reverse polarity magnetozones (as defined by at least three stratigraphically superposed samples) linked by conodont and palynofloral evidence from this study and the literature to Rhaetian to Triassic–Jurassic boundary age. This represents a significantly larger number of polarity zones than previously recognized in more condensed
Rhaetian sections from the literature, and by inference represents more time. These data are placed in a broader Late Triassic temporal framework by means of correlations to published magneto-biostratigraphic data from the Tethyan marine Pizzo Mondello section and the Newark astronomical polarity time scale (APTS). This framework is consistent with a position of the
Norian–Rhaetian boundary (as defined at Brumano and Pizzo Mondello by the first appearance of Misikella posthernsteini) within Newark magnetozones E17r–E19r in the ~ 207–210 Ma time interval, in basic agreement with the position originally estimated in the Newark using pollen biostratigraphy (E18 at 208–209 Ma). This framework is also consistent with the position of
the Triassic–Jurassic boundary interval (placed at Italcementi Quarry at the acme of Kraeuselisporites reissingeri coincident with a negative carbon isotope excursion) correlative to just above Newark magnetozone E23r and just below the oldest CAMP lavas dated at ~ 202 Ma. Hence, we estimate the duration of the Rhaetian to be ~ 5.5–8.5 Myr (or even longer if the
Triassic–Jurassic boundary is instead placed above the negative carbon isotope excursion as at Kuhjoch, which is the designated GSSP for the base of the Hettangian), and encompassing 9 magnetozones. This duration contrasts with a duration of ~ 2 Myr and only ~ 4 magnetozones in several alternative published magneto-biostratigraphic schemes.

I've Been Waiting For This For A Long Time

Walker, J., & Geissman, J. (2009). 2009 GSA Geologic Time Scale GSA Today, 19 (4) DOI: 10.1130/1052-5173-19.4-5.60

The Geological Society of America has just released its updated geological timescale for 2009 (here and here). A significant revision of this timescale is the Triassic section based on recent studies by Furin et al. (2006) and Kent and Olsen (2008). Most notably is the incorporation of the "long Norian" stage. In the previously published version of the timescale, the Carnian/Norian boundary was dated at 216.5 Ma. Now this boundary is dated at 228 Ma, which in the previous version was the date for the Ladinian/Carnian boundary (Middle/Late Triassic boundary).

The beginning of the Late Triassic is now dated at 235 Ma (previously a strong Middle Triassic date). Incredibly the majority of the Triassic now consists of the Late Triassic. In fact just the Norian stage (24 my) of the Late Triassic is longer than the combined Early (6 my) and the Middle (17 my) Triassic Epochs! The base of the Triassic is still at 251 Ma (defined by a GSSP); however, the age of the Triassic/Jurassic boundary has changed from 199.6 Ma to 201.6 Ma.

As it is now "official" the "long Norian" will have significant implications for the age of the Chinle Formation and other supposed "Carnian" fossil assemblages worldwide as suggested recently by studies such as that of Furin et al. (2006) and Irmis and Mundil (2008). As more GSSPs are established for the Triassic these dates should stabilize.

REFERENCES

Furin, S., Preto, N., Rigo, M., Roghi, G., Gianolla, P., Crowley, J.L., and Bowring, S.A., 2006, High-precision U-Pb zircon age from the Triassic of Italy: Implications for the Triassic time scale and the Carnian origin of calcareous nannoplankton and dinosaurs: Geology, v. 34, p. 1009–1012, doi: 10.1130/G22967A.1.

Irmis, R. B., and R. Mundil. 2008. New age constraints from the Chinle Formation resolve global comparisons of Late Triassic vertebrate assemblages. Journal of Vertebrate Paleontology 28:95A.

Kent, D.V., and Olsen, P.E.,2008, Early Jurassic magnetostratigraphy and paleolatitudes from the Hartford continental rift basin (eastern North America): Testing for polarity bias and abrupt polar wander in association with the central Atlantic magmatic province: Journal of Geophysical Research, v. 113, B06105, doi: 10.1029/2007JB005407.