In the first article, Hans Hess and Ben Thuy have teamed up to take a closer look at the origin and evolution of a poorly understood crinoid group, the cyrtocrinids. They present phylogenetic, palaeobiogeographic and palaeoecological evidence that suggests a deep-sea origin of these crinoids that temporarily invaded shallow seas in the Early Jurassic. At the same time, this is the last contribution by the late Hans Hess.
Bill Ausich is evaluating the Disparida with a parsimony-based phylogenetic study. The Disparida exhibit forms with both simple and highly specialized morphologies. Some of the families can be consistently identified as clades whereas others remain ambiguous.
Tom Baumiller and Forest Gahn present a new study on an old case of parasitism, the association of crinoids with platyceratid gastropods. This contribution convincingly demonstrates that the gastropods diminished the growth rates of the crinoids. The negative impact of the parasites leads to an increased length of the hindgut that allowed the crinoids to absorb more nutrients.
Again Tom Baumiller now with Angela Stevenson reconstructs crinoid predation intensity by looking at two comatulids. They show that one of the species has a slightly higher predation intensity that is probably due to a response to tactile stimulation that leads to crawling deeper into their perch.
A neoichnological approach is taken by Krystov Brom, Kazuma Oguri, Tatsuo Oji, Mariusz Salomon and Przemyslaw Salomon who show crawling traces produced by the extant stalked crinoid Metacrinus rotundus. These crinoids produce characteristic traces that have a good preservation potential. They conclude that autotomization and relocation were already present in the Triassic stem-group isocrinids.
A very unusual crinoid stem is described as a new species Trombocrinus hanshessi by Steve Donovan, Johnny Waters and Mark Pankowski. The specimen comes from the Devonian of Morocco and displays some peculiar features. The mesistele grew in a convolute manner and the proxistele was adapted to elevate the crown. The overall morphology looks like a trombone, unique among Palaeozoic crinoids.
Hans Hagdorn, Fabrizio Berra and Andrea Tintori report on a Middle Triassic obrution Lagerstätte from the Italian Alps. The juvenile and semiadult crinoids are referred to Encrinus aculeatus. Comparison with the holotype and material from Poland leads to the conclusion that the species concept of the genus is critical.
Didier Merle and Michel Roux dedicate a new species, Eocenocrinus hessi to Hans. The specimen comes from the Early Eocene of the French Pyrenées and is associated with Conocrinus romanensis and Democrinus londinensis. E. hessi is probably the oldest representative of the family Phrynocrinidae and lived on hard substrate in water depths up to 300 m.
Charles “Chuck” Messing takes a closer look at the extant crinoid Actinometra blakei. With the support of three new specimens, recently collected in the Western Atlantic, he is able to demonstrate that A. blakei is in fact a junior synonym of Comatula. However, it does not conform with Comatula and is thus assigned to a new genus, Hanshessaster.
Andrew Tenny and Steve Donovan report on a Carboniferous crinoid Amphoracrinus with only four arms. As there seem to be no signs of infestations, a genetic flaw is suspected. The crinoid adjusted by arranging its other arms at a right angle for efficient feeding.
James Thomka, Carlton Brett, Troy Bole and Hunter Campbell bring us an accumulation of disparid crinoids from the Upper Ordovician to notice. They discuss the implications for the palaeoecology and taphonomy of crinoid “logjam” assemblages from the type Cincinnatian of Ohio (USA) and show that unusual specimens can be still discovered even in well-studied assemblages.
Gary Webster looks at the fossil record of the Cromyocrinidae and Pirasocrinidae that replaced most of the camerate crinoids in the Late Palaeozoic. These dendrocrinid taxa became extinct in the Late Permian but occur worldwide and show a greater diversity than previously assumed because disarticulated ossicles are difficult to assign.