Permian chronostratigraphic subdivisions

Jin, Yg; Wardlaw, B.R.; Glenister, BF; Kotlyar, GV

doi:10.18814/epiiugs/1997/v20i1/003

Cited by 183 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The last appearance of Synapsida, Therapsida, Theriodontia, Cynodontia, Cynognathia, and Tritylodontidae is based on the Middle Jurassic tritylodontid genus Bienotheroides, because it is the latest appearing fossil taxon included in this analysis. Absolute age estimates were based on the time scales of Gradstein et al (1995), Opdyke (1995), and Yugan et al (1997) …”

Section: Appendixmentioning

confidence: 99%

Simplification as a Trend in Synapsid Cranial Evolution

Sidor¹

2001

Evolution

119

View full text Add to dashboard Cite

.— The prevalence and meaning of morphological trends in the fossil record have undergone renewed scrutiny in recent years. Studies have typically focused on trends in body size evolution, which have yielded conflicting results, and have only rarely addressed the question as to whether other morphological characteristics show persistent directionality over long time scales. I investigated reduction in number of skull and lower jaw bones (through loss or fusion) over approximately 150 million years of premammalian synapsid history. The results of a new skull simplification metric (SSM), which is defined as a function of the number of distinct elements, show that pronounced simplification is evident on both temporal (i.e., stratigraphic) and phylogenetic scales. Postcranial evolution exhibits a similar pattern. Skull size, in contrast, bears little relationship with the number of distinct skull bones present. Synapsid skulls carried close to their observed maximum number of elements for most of the Late Carboniferous and Early Permian. The SSM decreased in the Late Permian but, coincident with the radiation of early therapsids, the range of observed SSM values widened during this interval. From derived nonmammalian cynodonts in the Early Triassic through the earliest mammals in the Early Jurassic, both the minimum and maximum SSM decreased. Data from three representative modern mammals (platypus, opossum, and human) suggest that this trend continues through the Cenozoic. In a phylogenetic context, the number of skull elements present in a taxon shows a significant negative relationship with the number of branching events passed from the root of the tree; more deeply embedded taxa have smaller SSM scores. This relationship holds for various synapsid subgroups as well. Although commonly ascribed to the effects of long‐term selection, evolutionary trends can alternatively reflect an underlying intrinsic bias in morphological change. In the case of synapsid skull bones (and those of some other tetrapods lineages), the rare production of novel, or neomorphic, elements may have contributed to the observed trend toward skeletal simplification.

show abstract

Section: Appendixmentioning

confidence: 99%

Simplification as a Trend in Synapsid Cranial Evolution

Sidor¹

2001

Evolution

119

View full text Add to dashboard Cite

show abstract

“…Heavy dashed line in Haast Schist approximates boundary between schist derived from the Caples Terrane with that derived from the Torlesse Terrane. japonica (Gumbel) suggesting an Early Permian, Kungurian age, corresponding to an absolute date of around 270 to 272 Ma according to the recent time scale compilation of Yugan et al (1997). Triangles show locations of fusulinid limestone.…”

Section: Introductionmentioning

confidence: 99%

Permian fragmentation, accretion and subsequent translation of a low-latitude Tethyan seamount to the high-latitude east Gondwana margin: evidence from detrital zircon age data

et al. 2002

View full text Add to dashboard Cite

Ion microprobe analyses of detrital zircons in the Te Akatarawa Terrane, New Zealand, reveal that the age of unfossiliferous turbidites overlying a fusuline-and coral-bearing limestone block olistostromal mélange is no older than 255 ± 4 Ma (Late Permian). This is approximately 15 m.y. younger than the Kungurian age of the fusulinid limestone. We interpret this to indicate collapse of a Permian oceanic seamount as it entered a subduction zone along the Pacific margin of Gondwana. These turbidites differ markedly in composition from adjoining Permian to Middle Triassic sandstones of the Torlesse Terrane. Detrital zircon age data indicate predominantly Permian and Carboniferous ages for source rocks supplying the Te Akatarawa turbidites, but also reveal significant earlier Palaeozoic and Proterozoic components, ranging back to 1.9 Ga. The warm-water setting of limestone blocks and the short 15 m.y. time period between sedimentation and accretion onto a continental margin require the limestone to have formed in a low-latitude position probably off the northeast Australian (New Guinea) margin of Gondwana. Zircons within the sample underwent recrystallization at around 230 ± 11 Ma which may be related to alteration during accretion in a subduction zone environment. Over a period of 100 to 150 m.y. from 255 Ma the terrane underwent more than 5000 km translation along the continental margin southward to its current location as an exotic mini-terrane enclosed within the New Zealand Torlesse Terrane.

show abstract

“…Mei et al (1999a) and Mei and Henderson (2001) demonstrated that the first occurrence of N. exsculptus is within the N. pequopensis Zone. Accordingly, Ueno et al (2002) suggested that the conodont fauna, including R. bucaramangus, reported by Reimers (1991), is the middle Artinskian rather than the Bolorian because the N. pequopensis Zone is currently the uppermost zone of the Artinskian (Jin et al, 1997).…”

Section: Age Of the Rabeignathus Bucaramangus Faunamentioning

confidence: 97%

Early Permian Conodonts from the Baoshan Block, Western Yunnan, China

Yao

Jin

et al. 2004

Acta Geologica Sinica (Eng)

View full text Add to dashboard Cite

The Rabeignathus bucaramangus fauna was recently found from the limestone beds of the top part of the clastics‐dominated Dingjiazhai Formation in the Aluotian section, southern Baoshan Block, western Yunnan. With Rabeignathus bucaramangus as the dominant species, this fauna includes Rabeignathus bucaramangus (Rabe), Homeoiranognathus huecoensis (Ritter), Sweetognathus inornatus Ritter, Sweetognathus whitei (Rhodes), Mesogondolella cf. bisselli (Clark and Behnken) and a few of ramiform elements. The characteristics of the fauna suggest that it can be correlated with the upper part of the Sweetognathus whitei Zone and assigned to the Middle Artinskian.

show abstract

Permian chronostratigraphic subdivisions

Cited by 183 publications

References 0 publications

Simplification as a Trend in Synapsid Cranial Evolution

Simplification as a Trend in Synapsid Cranial Evolution

Permian fragmentation, accretion and subsequent translation of a low-latitude Tethyan seamount to the high-latitude east Gondwana margin: evidence from detrital zircon age data

Early Permian Conodonts from the Baoshan Block, Western Yunnan, China

Contact Info

Product

Resources

About