Fig 4 - uploaded by Hans Hagdorn
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Camera lucida drawing of MHI 1285/3. Abbreviations: IB -infrabasals, B -basals, R -radials, IBr1 -first primibrachials, IBr2 -second (non-axillary) primibrachials, IBr3 -third primibrachial, P -pinnules.
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... They are common and abundant components of fossil assemblages, being regularly observed in Palaeozoic and Mesozoic epicontinental marine deposits, most often as disarticulated ossicles. However, exceptionally well-preserved and articulated specimens have been extensively studied and described in Konservat-Lagerstätten such as those from the Anisian Muschelkalk of the Germanic Basin, Tatra Mountains, and the late Ladinian/early Carnian Cassian Formation in the Southern Alps (Lefeld 1958;Hagdorn 1996Hagdorn , 2011Hagdorn , 2020, among others (Hess and Messing 2011). Studies of Triassic Lagerstätten have been central to understanding the evolution and diversification of the group after the dramatic Permian/Triassic Boundary (PTB) biological crisis that led the class to the point of near-extinction (Paul 1988;Benton and Twitchett 2003;Hagdorn 2011;Hess and Messing 2011). ...
... Congruent fossil and molecular evidence indicates that post-Palaeozoic crinoids belong to the single monophyletic subclass Articulata and that they radiated from a small clade (Pawson 2007;Hagdorn 2011;Hess and Messing 2011;Rouse et al. 2013;Wright et al. 2017), which gave rise to all subsequent forms including present-day comatulids and stem-crinoids (Rouse et al. 2013;Oji and Twitchett 2015). Palaeontological studies also agree on a scenario of rapid evolution and diversification of post-Palaeozoic crinoids into two distinct lineages, the Encrinida, which are the emblematic crinoids of the Triassic, and the Holocrinida/ Isocrinida (Webster and Jell 1999;Benton and Twitchett 2003;Kashiyama and Oji 2004;Twitchett and Oji 2005;Hagdorn and Göncüoglu 2007;Webster and Lane 2007;Baumiller et al. 2010;Hagdorn 2011Hagdorn , 2020Hess and Messing 2011;Salamon et al. 2012Salamon et al. , 2015Rouse et al. 2013;Oji and Twitchett 2015;Cohen and Pisera 2017;Brosse et al. 2019;Saucède et al. 2019). The Encrinida are mainly known from rich fossil deposits of the western Tethys domain where their abundant ossicles are at the origin of the extensive crinoidal limestones of the German Upper Muschelkalk (Middle Triassic) (Hagdorn 2011). ...
... The Encrinida are mainly known from rich fossil deposits of the western Tethys domain where their abundant ossicles are at the origin of the extensive crinoidal limestones of the German Upper Muschelkalk (Middle Triassic) (Hagdorn 2011). They were unknown from the Lower Triassic so far and did not appear in the fossil record from the rocks older than early Anisian (Middle Triassic) in the Germanic Basin (Hagdorn 1999(Hagdorn , 2011(Hagdorn , 2020, or potentially latest Early Triassic (Nawrocki and Szulc 2000). In contrast, first representatives of the Holocrinida/Isocrinida lineage are reported from the rocks as old as middle Griesbachian (lower Induan; Early Triassic) from Oman (Oji and Twitchett 2015;Brosse et al. 2019). ...
Knowledge of the early evolution of post-Palaeozoic crinoids mainly relies on the well-preserved and abundant material
sampled in Triassic Konservat-Lagerstätten such as those from the Anisian Muschelkalk (Middle Triassic) of the
Germanic Basin. These crinoid-bearing Lagerstätten have been central to understanding the rapid evolution and diversification
of crinoids after the dramatic Permian/Triassic Boundary biological crisis that led the class to near-extinction.
The Encrinida are the emblematic crinoids of the Triassic. They are mainly known from rich fossil deposits where their
abundant ossicles are at the origin of the extensive crinoidal limestone beds of the German Upper Muschelkalk. So far,
they were first represented in the Middle Triassic by the family Dadocrinidae and genus Dadocrinus. In the present work,
a new species Dadocrinus montellonis sp. nov., is described based on a well-preserved, almost complete articulated specimen
from the Spathian (Lower Triassic) of Nevada (USA). The new species differs from other species of Dadocrinus by
its palaeobiogeographic position but also by its earlier stratigraphic occurrence and ancestral morphology. It represents
the first reported occurrence of Dadocrinus outside the Germanic Basin prior to the Middle Triassic and also the oldest
firm evidence of its presence in the Early Triassic (middle–late Spathian). This discovery sheds new light on the origin
of post-Palaeozoic crinoids. It suggests a much wider distribution than commonly assumed for the genus Dadocrinus
and implies that the first dadocrinids originated either in the Panthalassa or Tethys oceans, and then dispersed over long
distances in a relative short period of time.
... As originally applied, pseudomonocycly refers to the loss of the infrabasal circlet as is characteristic of extant crinoids (Ubaghs, 1978). The Triassic crinoid Aszulcicrinus provides a compelling example of this transition (Hagdorn, 2020). However, pseudomonocyclic crinoids may also emerge from dicyclic clades through the loss of basals (McIntosh, 1979) or radials (Lane, 1967). ...
http://deepblue.lib.umich.edu/bitstream/2027.42/172912/2/Contributions 34 - Baumiller Sp. Volume Lo Res.pdf
