Figure 1 - uploaded by Wayne Itano
Content may be subject to copyright.
Graphical representation of the phylogeny of the Holocephali (Dean, 1906, fig. 144). Note the hypothesised divergence of the lineage leading to Squaloraja from that leading to Recent holocephalans in the mid-Carboniferous.
Source publication
Squaloraja is a genus of chimaeriform fishes known from the Early Jurassic.
It has a dorsoventrally flattened body and a long median rostral cartilage. Males have a lance-like tenaculum that articulates with a central groove on the dorsal face of the median rostral cartilage. The genus is the only member of the family Squalorajidae, itself the only...
Contexts in source publication
Context 1
... Squaloraja are not common. Of particular interest would be an indication of when the branch leading to the Squalorajoidei and Squaloraja diverged from other Chimaeriformes, including the Chimaeroidei, which includes all Recent holocephalans. Several cladograms that include both Squaloraja and crown group holocephalans (Grogan et al., 2012, fig. 1.1; Lund & Grogan, 1997;Lund et al., 2014, fig. 5(a); Stahl, 1999) differ somewhat in topology but all imply that such a divergence took place no later than the Serpukhovian (Late Mississippian), since it would have occurred prior to the appearance of Echinochimaera. Echinochimaera is known from the Serpukhovian Bear Gulch Lagerstätte of ...
Context 2
... took place no later than the Serpukhovian (Late Mississippian), since it would have occurred prior to the appearance of Echinochimaera. Echinochimaera is known from the Serpukhovian Bear Gulch Lagerstätte of Montana, USA. The most recent cladistic analysis to include both Squaloraja and crown group holocephalans is that of Lebedev et al. (2021, fig. 17). This cladogram has less resolution than the others referred to here since it is based solely on dental characters. However, it implies a divergence of the lineage leading to Squaloraja and the lineage leading to Callorhynchus no later than the earliest known appearance of Protochimaera Lebedev & Popov, 2021in Lebedev et al., (2021 in ...
Context 3
... et al., (2021 in the Middle Mississippian (Tulian substage of the Visean stage). As pointed out by Lebedev et al. (2021), this implies the existence of a 'ghost lineage' greater than 130 My from the earliest squalorajoid to Squaloraja. In this context, it is interesting to note the early phylogenetic tree of the holocephalans from Dean (1906) (Fig. 1). While it is obsolete in several aspects, such as the association of the early holocephalans with Ptyctodus, a placoderm, it is quite prescient in showing the divergence of the squalorajoids from the chimaeroids in the mid-Carboniferous, despite the lack of fossil evidence in 1906. With regard to the paucity of fossil evidence for ...
Context 4
... to the Late Triassic (Norian), and of the Protochimaeroidei + Chimaeroidei from the Carboniferous (Serpukhovian) to the Late Triassic (Norian). The Norian occurrences of a callorhinchid chimaeroid, cf. Eomanodon sp. and of Myriacanthoidei indet. are both from the Franz Josef Land archipelago (Popov et al., 2009). Remarkably, Dean (1906) (Fig. 1) hypothesised a Palaeozoic origin for all three clades, even though pre-Jurassic fossils of members of those clades were unknown in 1906. ...
Citations
... The latter formation's boundary with the overlying Aux Vases Formation is an erosional unconformity that would, at least in part, represent the following marine regression (Rygel et al., 2008). This hypothesis has found independent support in the fossil record (Gradstein et al., 2012;Groves & Beason, 2006;Itano & Duffin, 2023), and the same sequence is also found elsewhere in the Illinois Basin (Nelson et al., 2002). Haq and Schutter (2008) provided absolute age dates for sea level changes between the Precambrian and Early Triassic. ...
ABSTRACT–– A new gyracanthid, Gyracanthus? jasperi sp. nov., is described based on partially articulated and isolated elements from the Lower Carboniferous (Mississippian) Waugh Member of the Ste Genevieve Formation, at the early tetrapod site near Delta, Iowa USA. One pectoral fin spine of the new gyracanthid is described using micro-computed tomography. Pectoral fin spines are characterized by the insertion on the fin spine being a half to one-third the length of the spine and maximum length:depth ratio 10:1. Pectoral fin spine ornamenting ridges converge at ≥ 90º along a low leading edge ridge, and ridge tubercles are oriented oblique to the ridge; the distal end of one pectoral is described using micro-computed tomography. The scapulocoracoids have an anteriorly curving bulbous apex, and a base length that is 35–40% of pectoral spine length. The procoracoid is associated with an unornamented ventral plate. A possible isolated dorsal fin spine is more symmetrical and less worn than the pectoral fin spines. Pelvic spines are dorsoventrally flattened, with oblique ridges meeting at approximately 100° proximally and 80° distally, along a smooth leading edge ridge. Scales, found on the partial articulated specimens and as isolated remains, are polyodontode with a flattened base. Adults of the new taxon are estimated to have been about one meter long. Deposition was in debris flows, within a sinkhole lake most likely removed from the edge of the ocean. Other Carboniferous gyracanthids from North America are reviewed.
urn:lsid:zoobank.org:pub:A2D947A7-8279-4AC6-A085-F1A2D12771BD
SUPPLEMENTAL DATA––Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
... Lastly, two additional contributions in this volume delve into Carboniferous vertebrates. Firstly, Itano and Duffin (2023) present compelling evidence for one or possibly two new holocephalan taxa from the Visean of Indiana, North America. Their research involves the description and comparison of various rostral cartilage and frontal claspers, leading to the identification of a new chimaeriform genus and species named Sulcacanthus schachti. ...
The International Symposium on Early and Lower Vertebrates (ISELV) aims to promote the study of the origin and early evolution of our own evolutionary lineage. This volume serves as an example of the most recent symposium held in Valencia, Spain, in June 2022. Since its inception in 1967, the ISELV has been organized 15 times prior to the latest conference in Valencia, which marked the 16th edition and the first time it was held in Spain in over 50 years. This symposium stands out as the sole recurring international meeting exclusively dedicated to the Palaeozoic vertebrate research community, putting special emphasis on topics concerning the origin, diversity, and early evolution of vertebrates (including the first tetrapods). The compilation presented in this volume represents the culmination of these conferences and serves as our tribute to two distinguished researchers in the field of Early Vertebrates: Dr. Philippe Janvier from the Muséum National d’Histoire Naturelle in Paris and Dr. Tiiu Märss from Tallinn University of Technology in Estonia.
