AGE AND COR RE LA TION OF LATE TRI AS SIC TETRA PODS
FROM SOUTH ERN PO LAND
Spencer G. LUCAS
New Mex ico Mu seum of Nat u ral His tory, 1801 Moun tain Road NW, Al bu quer que, NM 87104-1375, USA; e-mail: spencer.lucas@state.nm.us
Lucas, S. G., 2015. Age and cor re la tion of Late Tri as sic tetra pods from south ern Po land. Annales Societatis Geologorum Poloniae, 85: 627–635.
Ab stract: Age as sign ments of Tri as sic tetrapod fos sils can be achieved by di rect ref er ence to a scheme of Tri as sic land-ver te brate faunachrons (LVFs) that cor re lates Tri as sic tetrapod fos sil as sem blages to each other based solely on the tetrapod fos sils. Cor re la tion of Tri as sic tetrapod as sem blages to the stan dard global chronostratigraphic scale (SGCS, the “ma rine timescale”) is a sep a rate cross cor re la tion be tween the ver te brate biochronology and ma rine biochronology that usu ally re lies on other data (e. g., palynostratigraphy, magnetostratigraphy, radioisotopic ages) to be com pleted. Late Tri as sic tetrapod fos sils in south ern Po land are found at two strati graphic po si -tions, the Krasiejów and Lisowice lev els. The tetrapod as sem blage of the Krasiejów level is as signed to the early Adamanian LVF based pri mar ily on the strati graphic over lap of the phytosaur Parasuchus with the Adamanian in dex aetosaur Stagonolepis. The am phib i ans Cyclotosaurus and Gerrothorax, a Proterochersis-like tur tle and the aetosaur Paratypothorax from the Lisowice level in di cate it is as sign able to the Revueltian LVF. Cross cor re la -tions to the SGCS are less de fin i tive, but sug gest that the Krasiejów level is late Carnian and the Lisowice level is early/mid dle Norian. How ever, this cor re la tion of the Krasiejów level is con founded by dis agree ments over cor re la tion of the ma rine Carnian–Norian bound ary to nonmarine strata. In deed, the pos si bil ity that the Krasiejów tetra pods fill a gap in the early Norian re cord of tetra pods mer its con sid er ation. Such dif fi cul ties em pha size the value of cor re lat ing tetrapod as sem blages to each other us ing a land-ver te brate biostratigraphy/biochronology, in stead of im me di ately at tempt ing the more prob lem atic cor re la tion to the SGCS.
Key words: Late Tri as sic, Po land, land-ver te brate faunachron, Krasiejów level, Lisowice level, Adamanian, Revueltian.
Manu script re ceived 31 March 2015, ac cepted 28 May 2015
IN TRO DUC TION
Tri as sic tetrapod (am phib ian and rep tile) fos sils are known from across what was the Pangean supercontinent and have long been used in biostratigraphy and biochrono-logy, a tra di tion ex tend ing back to at least the 1870s. Lucas (1990) ad vo cated de vel op ing a global Tri as sic timescale based on tetrapod evo lu tion (also see Lucas and Hunt, 1993), and sub se quently Lucas (1998, 2010) pre sented a com pre -hen sive global Tri as sic tetrapod biochronology (Fig. 1). This biochronological timescale di vides the Tri as sic into eight time in ter vals (land-ver te brate faunachrons, LVFs) based on biochronological data that rep re sent tetrapod evo lu tion ary events. This scheme has been tested and re fined for nearly two de cades and was last re viewed by Lucas (2010).
Be fore 2000, lit tle was known of Pol ish Late Tri as sic tetra pods, so re views of Tri as sic tetrapod biostratigraphy/ biochro nol ogy be fore that time (e.g., Lucas, 1998, 1999) made no men tion of Pol ish Tri as sic tetra pods. How ever,
this changed rad i cally with the dis cov ery of two ex ten sive bonebeds and other tetrapod oc cur rences in south ern Po land (Silesia) of Late Tri as sic age (Fig. 2). These bonebeds now rank among the most im por tant Late Tri as sic tetrapod lo cal -i t-ies known.
Else where in this vol ume, Szulc et al. (2015) re view in de tail the strati graphic con text of Late Tri as sic tetrapod fos -sils from Po land, and I fol low their re view in iden ti fy ing two nar row strati graphic in ter vals that pro duce these fos sils, the Krasiejów and Lisowice lev els (Fig. 2). Pub lished age as sign ments for both lev els, which have mostly been cor re -lated di rectly to the ma rine timescale, are con tro ver sial (Szulc et al., 2015). Here, I dis cuss the age of the Sile- sian Up per Tri as sic tetrapod-fos sil-pro duc ing lev els with re gard to the tetrapod biochronology of the Late Tri as sic and then, sep a rately, with re gard to the stan dard global chronostrati-graphic scale (SGCS).
COR RE LA TION AND CROSS
COR RE LA TION
Land-ver te brate faunachrons (LVFs) are biochronolo-gical units, and their be gin nings are de fined by biochrono-log i cal events (Lucas, 1998, 2010). Each LVF be gins with the FAD (first ap pear ance da tum) of a tetrapod in dex taxon, usu ally a ge nus, though spe cies are used if they pro vide greater biochronologic res o lu tion (Fig. 1). In so do ing, the end of an LVF is de fined by the be gin ning of the suc ceed ing LVF, which is the FAD of an other tetrapod in dex taxon. This is a pre cise way to de fine LVF bound aries, so LVFs are in ter val biochrons.
A dis tinc tive as sem blage of ver te brate fos sils char ac ter izes each LVF. This tetrapod as sem blage is the pri mary ba -sis for char ac ter iza tion of the LVF. In dex fos sils of LVFs meet the cri te ria of true in dex fos sils (tem po rally re stricted, com mon, wide spread, eas ily iden ti fied) and do not in clude en demic or rare taxa that hap pen to be re stricted to a LVF, usu ally as sin gle re cords. The tetrapod biochronology of the Tri as sic is a timescale in de pend ent of the SGCS (Fig. 1).
The Chinle Group strata of the Amer i can South west yield the best stud ied and most com plete fos sil re cord of Up per Tri as sic tetra pods (e.g., Lucas, 1993, 1997; Long and Murry, 1995; Lucas and Huber, 2003). The Chinle Group tetrapod fos sil re cord thus pro vided the ba sis for def i ni tion of the four Late Tri as sic LVFs: Otischalkian, Adamanian, Revueltian and Apachean (Fig. 1). Of great im por tance, tetrapod fos sil as sem blages from Texas (Otischalkian char -ac ter is tic as sem blage), Ar i zona (Adamanian char -ac ter is tic as sem blage) and New Mex ico (Revueltian and Apachean char ac ter is tic as sem blages) are stratigraphically superposed and thus are time suc ces sive (e.g., Lucas 1993, 1997; Lucas and Hunt, 1993; Lucas et al., 2007b; Spielmann and Lucas, 2012). The Chinle as sem blages yield phytosaurs, aetosaurs and metoposaurs use ful for broad cor re la tion, and a bur -geon ing microvertebrate biostratigraphy also sup ports the macrovertebrate-based cor re la tion (Lucas, 2010).
Use of a tetrapod biochronology that as signs ages and cor re lates based on the tetra pods, them selves, frees ver te brate biostratigraphers from at tempt ing to cor re late tetra -pods di rectly to the SGCS. This is best ex em pli fied by the North Amer i can land-mam mal “ages,” a set of biochronolo- gical units cre ated by Wood et al. (1941) to or ga nize Ce no -zoic, mam mal-dom i nated as sem blages, pri mar ily from wes- tern North Amer ica. As an ex am ple, in that scheme a fos sil mam mal as sem blage can be as signed to the Barstovian land-mam mal “age,” and cor re la tion within the Barstovian can be based only on the known dis tri bu tion of the mam mal fos sils. The ques tion of cor re lat ing the Barstovian to the SGCS is a sep a rate prob lem not re solved by mam ma lian bio-chro nol ogy. In stead, magnetostratigraphy and radioisotopic ages in di cate the Barstovian spans ~12.5–15.5 Ma, so it is over laps the Langhian and Serravalian ma rine stages of the Mio cene on the SGCS (Tedford et al., 2004). No ver te brate biostratigrapher tries to make that cor re la tion (which I call a cross cor re la tion) based on mam mals, and in the lit er a ture of North Amer i can mam ma lian biochronology, Barstovian is of ten used with lit tle or no ref er ence to cross cor re la tion to the SGCS.
Fig. 1. The Tri as sic timescale based on tetrapod biostratigra-phy and biochronology. Tri as sic SGCS based on Lucas et al. (2012) and Ogg et al. (2014). Mod i fied from Lucas (2010).
Fig. 2. Strati graphic dis tri bu tion of the two ver te brate-fos sil-bear ing lev els in the Up per Tri as sic of Silesia (af ter Szulc et al., 2015, fig. 2) and in dex map of Po land show ing lo ca tion of area with fos sil lo cal i ties.
The im por tant les son is that a ver te brate biochronologi- cal scheme al lows ages to be as signed and cor re la tions to be de ter mined by the ver te brates, them selves. Of course, these cor re la tions are based on biostratigraphic data that is in her -ently in com plete, so that the ac tual tem po ral ranges of the taxa be ing used to cor re late are not es tab lished with cer tainty. The cor re la tion to the SGCS is a sep a rate cross cor re -la tion be tween the ver te brate biochronology and ma rine biochro nol ogy that usu ally re lies on other data (e.g., paly-nostratigraphy, magnetostratigraphy, radioisotopic ages) to be com pleted. In some places, a ter res trial/fresh wa ter fos sil ver te brate is found dis placed in ma rine de pos its, which al -lows some di rect cross cor re la tion of ver te brate taxa to the SGCS, but typ i cally that cross cor re la tion re lies wholly on non-ver te brate-fos sil data.
POL ISH LATE TRI AS SIC TETRA PODS
The Pol ish fos sil re cord of Late Tri as sic tetra pods ad -vanced greatly dur ing the 1990s, when sci en tific study of the ex ten sive bonebed in the Krasiejów clay pity near Opole be -gan, and much has been pub lished since (see es pe cially the re views by Dzik and Sulej, 2007, and Szulc et al., 2015).
Dzik et al. (2008) an nounced the dis cov ery of a sec ond, stratigraphically higher Up per Tri as sic bonebed at the Lipie Œl¹skie clay pit near Lubliniec. This bonebed yields an as -sem blage dom i nated by dicynodonts and archosaurs. There are three other ap prox i mately cor re la tive fos sil ver te brate lo cal i ties in Silesia. An other bonebed in the WoŸniki clay pit yields ver te brates sim i lar to those from Lipie Œl¹skie (Sulej et al., 2011). Sulej et al. (2011) cor re lated the WoŸ- niki as sem blage with the Krasiejów lo cal ity, but Szulc et al. (2015) ar gue con vinc ingly that the WoŸniki as sem blage and the Lipie Œl¹skie as sem blage are stratigraphically equiv a lent and sub -sume it un der what they call the Lisowice level (Fig. 2).
Bones from Porêba were dis cov ered in 2008 and in -clude am phib i ans, tur tles, and aetosaurs, among oth ers, and have in part been de scribed (Sulej et al., 2012; NiedŸwiedzki et al., 2014). This lo cal ity, and very re cently dis cov -ered bones from an other lo cal ity at Zawiercie, are stratigra-phically equated to Lipie Œl¹skie (e.g., Racki, 2010; Szulc et
al., 2015b). Thus, the Lisowice level com prises the fos sil
ver te brate lo cal i ties at Lipie Œl¹skie, WoŸniki, Porêba and Zawiercie.
PRE VI OUSLY AS SIGNED AGES
AND COR RE LA TIONS
There have been two dif fer ent sets of age as sign ments of the Krasiejów and the Lisowice lev els, one by Dzik and col lab o ra tors (e.g., Dzik and Sulej, 2007; also see Pieñko-wski et al., 2014) and the other by Szulc et al. (2015). These are al most ex clu sively di rect cor re la tions to the SGCS. Lucas et al. (2007a) and Lucas (2010) cor re lated the Krasie- jów level di rectly to the tetrapod biochronology, and Szulc
et al. (2015) did so with the Lisowice level.
Szulc et al. (2015) pres ent a de tailed re view of these and other age as sign ments, es pe cially those based on data
other than ver te brate biochronology, ob vi at ing the need for an ex ten sive re view here. Nev er the less, some of these age as -sign ments are dis cussed be low, es pe cially to the ex tent that they agree or dis agree with the cor re la tions ad vo cated here.
COR RE LA TION TO LATE TRI AS SIC
LVFS
Krasiejów level
The Krasiejów level in cludes the fol low ing biochrono-gically sig nif i cant tetrapod taxa: the am phib i ans
Cycloto-saurus and MetopoCycloto-saurus, the phytosaur Parasuchus (“Pa-leorhinus”), and the aetosaur Stagonolepis (e.g., Dzik and
Sulej 2007; Lucas et al., 2007a; Sulej, 2010; Szulc et al., 2015). Lucas et al. (2007a) pub lished the first ex plicit cor re la -tion of the Krasiejów level to the Tri as sic LFVs, as sign ing it an Otischalkian age. This fol lowed the long held idea that the phytosaur Parasuchus is a ro bust in dex taxon of the Otischal-kian LVF (Hunt and Lucas, 1991; Lucas et al., 2007a).
How ever, Lucas (2010) con cluded that North Amer i can and Eu ro pean re cords of the char ac ter is tic Adamanian aeto- saur Stagonolepis in di cate that some Parasuchus re cords should be con sid ered early Adamanian in age. Thus, if all
Stagonolepis re cords are re garded as Adamanian (as they
were by Lucas 1998), then re cords of Parasuchus from the Ger man Kieselsandstein and Blasensandstein (this in cludes, by my tax on omy, phytosaurs termed Paleorhinus and Ebra-
chosuchus by But ler et al., 2014) and the Pol ish Krasiejów
lo cal ity are Adamanian. This is also con sis tent with the Chinle Group re cord of Parasuchus at the Placerias/Downs quar ries in the Blue water Creek For ma tion in east ern Ar i -zona, in what I have re garded as old est Adamanian strata in the Chinle Group (Lucas, 2010). Thus, rec og niz ing that
Parasuchus re cords are not strictly Otischalkian (some are
early Adamanian), and that Stagonolepis re cords are strictly Adamanian, clar i fies cor re la tion in the Otischalkian–Ada-manian in ter val.
In Ger many, the Schilfsandstein (Stuttgart For ma tion) pro duces Metoposaurus and Parasuchus but lacks Stagono-
lepis, so it has been as signed an Otischalkian age (Lucas
1998, 1999, 2010; Fig. 3). Stratigraphically higher, the stra-tigraphic in ter val be tween the Schilfsandstein and the Stu-bensandstein (the clas sic Rote Wand, Lehrberg Schichten, Blasensandstein and Kieselsandandstein; Fig. 3) pro duces
Stagonolepis, Parasuchus and Metoposaurus, and is as -signed an Adamanian age (Lucas, 2010; Fig. 3). Milner and Schoch (2004) claimed the pres ence of Metoposaurus in the Revueltian Stubensandstein of Ger many, They based this claim on a skull ac quired by the Brit ish Mu seum in 1862, listed in the mu seum re cords as com ing from “the Mid dle Keuper near Stuttgart, Württemburg.” Fraas (1889, p. 137) stated the skull came from “Feuerbacher Heide bei Stutt-gart” and pro vided a brief de scrip tion of the skull, which had never been il lus trated. De spite this de scrip tion, Milner and Schoch (2004, p. 244) stated that “it is ques tion able if Fraas ever saw the spec i men.” Feuerbacher Heide was a small com mu nity that is now part of greater Stuttgart, where stone quar ries in the Schilfsandstein yielded many tetrapod spec i mens in clud ing Metoposaurus, the phytosaur
Zanclo-don arenaceus and the sphenosuchian Dyoplax (e.g., Hunt,
1993; Lucas et al., 1998; Hungerbühler, 2001). Thus, it makes em i nent sense for the Brit ish Mu seum metoposaur skull to have come from a stone quarry at Feuerbacher Heide, as stated by Fraas, who had a de tailed first hand knowl edge of the Feuerbacher lo cal i ties and fos sils.
Nev er the less, Milner and Schoch (2004) claimed that the BMNH skull came from the Mid dle Stubensandstein at Aixheim. They based this con clu sion on the pres er va tion of the spec i men, stat ing that the “three di men sional creamy-white bone” and “green coarse sand stone” of the BMNH spec i men ex cludes its prov e nance as Schilfsandstein. How -ever, not all spec i mens from the Schilfsandstein are black, crushed bone as Milner and Schoch (2004) claim (see for ex am ple, the type of Zanclodon arenaceus: Hungerbühler, 2001b, figs 1, 2), and “green coarse sand stone” does not ex -clude the Schilfsandstein lithologically.
In deed, the orig i nal lo cal ity data with the Brit ish Mu -seum skull pre clude its prov e nance as mid dle Stubensand-stein at Aixheim. Thus, Aixheim is not near Stuttgart, it is ~90 km to the SSW (Hungerbühler, 1998, fig. 1). In 1862, Aixheim would have been at least a two-day jour ney by
horse from Stuttgart, and thus would not have been descri-bed as “near Stuttgart.” Fur ther more, the orig i nal at tri bu tion to the “Mid dle Keuper” ex cludes the Stubensandstein, as the Schilfsandstein was tra di tion ally con sid ered Mid dle Keuper in Baden-Württemberg (Geyer and Gwinner, 1991). Fi nally, no well provenanced Ger man metoposaur has ever been found in the Stubensandstein; all are from the Schilf-sandstein-Lehrberg Schichten in ter val (Lucas, 1999). Thus, I con clude that Milner and Schoch’s (2004) claim that the Brit ish Mu seum skull is from the Stubensandstein, and thus Revueltian in age, is based on spe cious rea son ing and re ject it (also see Lucas et al., 2007b).
I thus fol low Lucas (2010) and con tinue to re gard the Krasiejów level as early Adamanian. Par tic u larly com pel -ling is that the ver te brate biochronology cor re lates it to the Adamanian strati graphic in ter val be tween the Schilfsand-stein and StubensandSchilfsand-stein in Ger many.
Lisowice level
Biochronologically sig nif i cant tetrapod taxa re ported and/or doc u mented from the Lisowice level in clude the am
-Fig. 3. Biostratigraphy of the Carnian–Norian bound ary in ter val in the Keuper sec tion of the Ger manic Ba sin. Based pri mar ily on Kozur and Bachmann (2008), Kozur and Weems (2010), Kuerschner and Herngreen (2010) and Lucas (2010). Mod i fied from Lucas et al. (2012).
phib i ans Cyclotosaurus and Gerrothorax, the tur tle cf.
Proterochersis, an aetosaur I judge to be Paratypothorax (com
-pare the osteoderms il lus trated in Sulej et al., 2012 with those of Paratypothorax il lus trated by Long and Murry, 1995 and Lucas et al., 2006) and a large dicynodont (Dzik
et al., 2008; Sulej et al., 2012; NiedŸwiedzki et al., 2012,
2014; Œwi³o et al., 2014). Szulc et al. (2015) rep re sents the first ex plicit cor re la tion of the Lipie Œl¹skie boned to the Tri as sic LVFs, as sign ing it a Revueltian age.
Late Tri as sic dicynodont re cords are of Otischalkian– Adamanian age, ex cept for one Revueltian? re cord from Ar -gen tina (Lucas and Wild, 1995; Lucas, 2010). (There is a pu ta tive Cre ta ceous re cord from Aus tra lia (Thulborn and Turner, 2003), but its re li abil ity is ques tion able.) In Ger many, the best known and most di verse Keuper tetrapod as -sem blage is that of the Lower Stubensandstein (Löwenstein For ma tion). This Revueltian-age as sem blage (Lucas, 1999, 2010) in cludes the am phib i ans Cyclotosaurus and
Gerro-tho rax, the ear li est Eu ro pean tur tles (in clud ing Protero-chersis), and the aetosaur Paratypothorax (e.g., Lucas,
1998, 1999, 2010). These taxa sup port cor re la tion of the ver te brate fos sils from the Lisowice level is to the Lower Stubensandstein as sem blage and thus in di cate a Revueltian age (Szulc et al., 2015).
Some of the ver te brates of the Lisowice level have been used to ad vo cate a youn ger age (“Rhaetian,” which would be an Apachean age in the land-ver te brate biochronology: Fig. 1). How ever, these are cor re la tions based on per ceived stage of evo lu tion or on poorly known taxa with few re cords (the mammaliaform tooth from Lipie Œl¹skie as signed to
Hallauthe- rium). In stead, I fa vor cor re la tions based on welles tab lished and longstud ied in dex taxa such as am -phib i ans and aetosaurs.
COR RE LA TION TO THE SGCS
Re cords of nonmarine Tri as sic tetra pods in ma rine strata (Lucas and Heckert 2000), palynostratigraphy, conchostra-can biostratigraphy, magnetostratigraphy and radioisotopic ages pro vide some ba sis for cor re la tion of the LVFs to the stan dard global chronostratigraphic scale (Fig. 1). Nev er the
-less, re li able data for this cross cor re la tion re main rel a tively sparse, so the cor re la tion of the LVFs to the SGCS is still im -pre cise in many time in ter vals. Thus, the cross cor re la tions shown here (Figs 1, 4) are open to im prove ment and/or mod i -fi ca tion.
Krasiejów level
If we ac cept the cross cor re la tion of the LVFS to the SGCS ad vo cated by Lucas (2010), then the Krasiejów level is late Carnian. Most pub lished di rect cor re la tions to the SGCS have as signed the Krasiejów level to the Carnian (e.g., Dzik and Sulej, 2007), but Szulc et al. (2015a, b; also see Szulc, 2005), largely based on palynostratigraphy, as -signed it to the Norian.
I cross cor re late the Adamanian to the late Carnian age based on palynostratigraphy, conchostracan biostratigra-phy, se quence stra tig ra phy and magnetostratigraphy (Lucas
et al., 2012). Kozur and Weems (2007, 2010) and Lucas et
al. (2012) dis cussed at length the biostratigraphic ev i dence to sup port a late Carnian (Tuvalian) cor re la tion of the Ada-manian, and I briefly re view it be low. How ever, some mag-netostratigraphic cor re la tions, no ta bly by Muttoni et al. (2004), re peated re cently by Maron et al. (2015), places the Norian base much lower in nonmarine strata than did Lucas
et al. (2012).
Lisowice level
If we ac cept the cross cor re la tion of the LVFS to the SGCS ad vo cated by Lucas (2010), then the Lisowice level is early-mid dle Norian. In con trast, Dzik and col lab o ra tors as signed the Lisowice level a late Norian and/or Rhaetian age (e.g., Dzik et al., 2008; NiedŸwiedzki et al., 2012; Sulej
et al., 2012; Œwi³o et al., 2014). This prompted Dzik et al.
(2008) to ar gue that the ap par ently diachronous (an oma -lously young) oc cur rence of some ver te brate taxa at the Lipie Œl¹skie lo cal ity in di cates very dif fer ent ver te brate com mu ni ties lived at the same time in dif fer ent parts of the Cen tral Eu -ro pean Tri as sic ba sin. How ever, the Lisowice level shares ver te brate taxa with Revueltian strata else where, which are con vinc ingly cross cor re lated to the earlymid dle Norian. In
-Fig. 4. Nonmarine cor re la tion of the Carnian–Norian bound ary (af ter Lucas et al., 2012) show ing cor re la tion of Krasiejów and Lisowice lev els pro posed here.
deed, cor re lat ing the Lisowice level to the early-mid dle Norian (Revueltian) based on shared in dex taxa is more par -si mo ni ous than ar gu ing for great diachroneity of tetrapod taxa that lived in a sin gle depositional ba sin.
Fur ther more, Szulc et al. (2015) re view the ba sis for a Rhaetian cor re la tion of the Lisowice level and dem on strate that it is du bi ous. All biostratigraphic data, par tic u larly palynostratigraphy and land-ver te brate biochronology, agree that the Lisowice level is ei ther early or mid dle Norian (Szulc et al., 2015).
DIS CUS SION
Lithostratigraphic con sid er ations
An im por tant lithostratigraphic da tum in the Tri as sic sec tion in Silesia is the Reed Sand stone, which has long been known to be the Pol ish ex pres sion of the Schilfsand-stein (Stuttgart For ma tion; Fig. 2). The SchilfsandSchilfsand-stein has a well es tab lished early Carnian (Julian) age in Ger many (e.g., Kozur and Bachmann, 2008). In Silesia, the early Car- nian Reed Sand stone is stratigraphically be low the Krasie-jów and Lisowice lev els (Fig. 2), so it sets a max i mum age for these bonebear ing in ter vals. More im por tantly, equiv a -lence of the Schilfsandstein and Reed Sand stone in vites com par i son of the Keuper sec tion above the Schilfsandstein in Ger many and above the Reed Sand stone in Po land. Such com par i son might be used to in fer some lithostratigraphic con straints on cor re la tion of the Ger man and the Pol ish sec -tions (Szulc et al., 2015).
In south ern Po land, the strata that con tain the Krasiejów and Lisowice lev els are a rel a tively thin, mudstonedom i -nated sec tion (Fig. 2). They re sem ble some parts of the post-Schilfsandstein Keuper in Ger many (no ta bly parts of the mudstone-dom i nated units) but are much thin ner and lack the strati graphic ar chi tec ture of the Ger man sec tion. Most no ta ble is the ab sence of a sub stan tial sand stone in ter -val in Silesia, the Stubensandstein of the Ger man sec tion.
My cor re la tions of the Krasiejów and Lisowice lev els in di cate that the ap prox i mately 30mthick, mudstonedom -i nated sec t-ion that they en com pass ranges from late Carn-ian through early-mid dle Norian, which equates it to much of the Weser For ma tion (Oberer Gipskeuper) through much of the Löwenstein For ma tion in the Ger man sec tion (Fig. 2). This cor re la tion sug gests that the Pol ish sec tion is a con -densed and likely hi a tus-laden cor re la tive of a sig nif i cant por tion of the Ger man Keuper.
In con trast, Szulc et al. (2015) ad vo cate an early to mid -dle Norian age for both the Krasiejów and Lisowice lev els, which greatly re duces the time in ter val be tween the bone-bear ing lev els. This would cor re late the Silesian bonebear ing in ter val to only part of the Löwenstein For ma -tion. In deed, Szulc (2005) and Szulc et al. (2015b) pro pose an over all con tin u ous de po si tion of the Silesian Keuper sec -tion, in con trast to “the main Eo-Cim mer ian disconformity” usu ally iden ti fied at or near the Norian base in the west ern Ger manic Ba sin. If so, early Norian ver te brate fau nas may be to tally ab sent from Ger many, and the Krasiejów fauna may fill the hi a tus, and thus rep re sent an oth er wise un re -corded early Norian tetrapod as sem blage.
Palynostratigraphy
Palynozonation of the Silesian Up per Tri as sic is based pri mar ily on the work of Or³owska-Zwoliñska (1983, 1985). In her zonation, the Krasiejów level is in her subzone IVa, and the Lisowice level is in subzone IVb of her “Corollina
meyeriana Zone.” Kuerschner and Herngreen (2010) re -viewed the palynozonation of Or³owska-Zwoliñska to place the Carnian–Norian bound ary within her “Corollina
meye-riana Zone,” in the lower part of her subzone IVa. Cirilli
(2010, fig. 2), how ever, sug gested the Norian base is at the base of the “Corollina meyeriana Zone” by in di cat ing in the fig ure the FAD of Classopollis meyerianus (= Corollina
me-ryeriana) at the base of the Norian. How ever, in her text,
Cirilli (2010, p. 289) con tra dicted this by stat ing that the Car-nian–Norian bound ary is within the “Corollina meyeriana Zone” of Or³owska-Zwoliñska.
My as sign ment of a late Carnian age to the Krasiejów level is con sis tent with the place ment of the Carnian–Norian bound ary of Kuerschner and Herngreen (2010). How -ever, as Szulc et al. (2015b) note, there is some un cer tainty and im pre ci sion in plac ing the base of the Norian with re -gard to the palynozonation of Or³owska-Zwoliñska. This is part of the ba sis for their ar gu ment that the Krasiejów level is Norian. Clearly, palynological cor re la tion of the Carnian– Norian bound ary in the Silesian sec tion is im pre cise, de bat -able and should be im proved.
The palynological cor re la tions, how ever, are much more de fin i tive re gard ing the age of the Lisowice level. It is in zone IVb of Or³owska-Zwoliñska, agreed on by all to be Norian.
Conchostracan biostratigraphy
Kozur and Weems (2005, 2007, 2010) de vel oped a de tailed conchostracan biostratigraphy for the nonmarine Tri -as sic of Eu rope and North Amer ica. This is cross cor re lated to the SGCS pri mar ily based on the Ger man Tri as sic sec -tion. In eval u at ing the Up per Tri as sic conchostracan re cord in Silesia, Kozur and Weems (2010) as signed the Krasiejów level to their late Carnian Laxitextella seegisi Zone and the Lisowice level to their early Rhaetian Gregoriusella
polo-nica Zone. To my knowl edge, Laxitextella has no Norian
re cords, so this conchostracan ge nus at Krasiejów in di cates a Carnian age, though the early Norian hi a tus in the Ger man sec tion may af fect this con clu sion. Thus, it is dif fi cult to que-stion Kozur and Weems’ (2010) cross cor re la tion of the Kra-siejów level, which is con sis tent with the ver te brate biochro-nological data and sup ported by at least one view of the paly-nostratigraphy. How ever, as sign ing the Lisowice level a Rhaetian age based on conchostracans con tra dicts the cross cor re la tion based on tetrapod biochronology and palynostra-tigraphy (see com ment by Nitsch in Szulc et al., 2015).
It is be yond the scope of this pa per to re-eval u ate the conchostracan biostratigraphy of Kozur and Weems, but this ex ten sive biostratigraphic scheme needs fur ther test ing. Such test ing has be gun in the Early Tri as sic (e.g., Becker, 2015) and prob lems with the Late Tri as sic cor re la tions are dis cussed by Maron et al. (2015) and Weems and Lucas (2015).
The long Norian
The Late Tri as sic timescale is poorly con strained due largely to the dearth of re li able radioisotopic ages that can be re lated pre cisely to biostratigraphy com bined with ev i -dent con tra dic tions be tween biostratigraphic and mag netostrati graphic cor re la tions. These prob lems are most ap par -ent with re gard to the age and cor re la tion of the Carnian– Norian bound ary (base of the Norian stage). Lucas et al. (2012) re viewed the avail able age data per tain ing to the Carnian–Norian bound ary to con clude that the “long No-rian” in cur rent use by many work ers, which places the Carnian–Norian bound ary at ~ 228 Ma, is in cor rect. The ev -i dence sup ports a Nor-ian stage that -is much shorter than pro posed by these work ers, so the Carnian–Norian bound -ary is con sid er ably youn ger than this, close to 220 Ma in age (Fig. 1).
Crit i cal to this con clu sion is the cor re la tion of the Car-nian–Norian bound ary in nonmarine strata of Eu rope and North Amer ica, and its in te gra tion with ex ist ing radioisoto-pic ages and magnetostratigraphy. Three biostratigraphic datasets (palynomorphs, conchostracans and tetra pods) re li -ably iden tify the same po si tion for the Carnian–Norian bound ary (within nor mal lim its of biostratigraphic res o lu -tion) in nonmarine strata of the Chinle Group (Amer i can South west), New ark Supergroup (east ern USA and Can ada) and the Ger man Keuper. In re cent years a cor re la tion based solely on magnetostratigraphy has been pro posed be tween the Pizzo Mondello sec tion in Sic ily and the New ark sec tion (Muttoni et al., 2004). Lucas et al. (2012) con cluded that this cor re la tion, which ig nores ro bust biostratigraphic data, places the Norian base much too low in the New ark Ba sin sec tion, yet it be came the pri mary jus ti fi ca tion for plac ing the Carnian–Norian bound ary at ~228 Ma (based on New -ark cyclostratigraphy).
Nev er the less, the “long Norian,” if ac cepted, cross cor -re lates the Adamanian to the Norian, which would make the Krasiejów level Norian, as Szulc et al. (2015b) con clude. Fur ther more, the pos si bil ity that the Carnian–Norian boun-dary cor re lates to a level within the Adamanian, and that the Krasiejów level is youn ger than the Norian base should be con sid ered. In these ways, a Norian age for the Krasiejów level is pos si ble. How ever, my anal y sis of the avail able data sug gests this is un likely, so I re gard the Krasiejów level as late Carnian.
CON CLU SIONS
1. In south ern Po land (Silesia), Up per Tri as sic tetrapod fos sils are known from two nar row strati graphic in ter vals, the Krasiejów level and the Lisowice level.
2. Tetrapod in dex taxa sup port as sign ing an early Ada- manian age to the Krasiejów level.
3. Tetrapod in dex taxa sup port as sign ing a Revueltian age to the Lisowice level.
4. Cross cor re la tion to the SGCS in di cates that the Adamanian Krasiejów level is late Carnian, whereas the Revueltian Lisowice level is early-mid dle Norian.
5. These cor re la tions im ply that the Silesian Up per Tri
as sic sec tion is a con densed and likely hi a tusladen cor re la -tive of a sig nif i cant por tion of the Ger man Keuper.
6. Nev er the less, un cer tain ties with re gard to biostrati-graphic ranges and cor re la tions of tetrapod, palynomorphs and conchostracans, as well as dis agree ment about the du ra -tion of the Norian, make it pos si ble that the Krasiejów level is Norian. In con trast to other data, conchostracan-based cross cor re la tions in di cate the Lisowice level is Rhaetian, and should be re-ex am ined.
Ac knowl edg ments
I thank Grzegorz Racki and Joachim Szulc for in vit ing this con tri bu tion, and for ed u cat ing me about many de tails of the Sile-sian Up per Tri as sic. Grzegorz Racki and Cesar Leandro Schultz pro vided help ful re views that im proved the manu script.
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