The extant threshers have a worldwide distribution in temperate to tropical waters, preying on pelagic & bottom fishes and cephalopods. They are best characterized by their elongated tails that are used to corral and/or stun prey. Alopias superciliosus (LOWE 1840) and A. vulpinus (BONNATERRE 1788), the two species that currently inhabit the western Atlantic, can be found from coastal waters to well off shore and to a depth of 500m. The third species, A. pelagicus NAKAMURA 1935 is not found in the Atlantic and is the most pelagic of the genus.
Modern threshers have cutting dentitions of rather homogeneous teeth even between those of the anterior and lateral hollows, Two species, vulpinus and pelagicus have three anterior and 19-23 lateral files that display little difference between sexes. In contrast, superciliosus has two anteriors, less than a dozen laterals and strong sexual dimorphism. These differences can be seen in the dentition slide-show and the below tooth-sets.
The Alopias dentition can be broadly described as having a cutting-design (more clutching-like in superciliosus males) with monognathic & gradational heterodonty. Except for the anterior-most positions, the cusps are distally inclined having a rather hooked appearance, particularly in narrow-crowned versions. The cutting-edge is smooth, usually extending well out onto the distal shoulder. The crown overhangs the labial face of the root. The root is thick and "C"-shaped with well-developed lobes; depending on species and tooth-position the nutrient groove may be distinct or absent (normally present in all superciliosus tooth-positions). Upper and lower teeth are very similar to each other in each species. Within a given dentition-set, lower teeth tend have shorter cusps than their upper counterparts.
Published Fossil Record
As a starting point, Cappetta (1987:105-07) included eight fossil taxa:
A. denticulatus CAPPETTA 1981 Ypresian, Morocco
A. crochardi WARD 1978 Ypresian, England
A. exigua (PROBST 1879) Lwr Oligocene - Mid Miocene, Europe
A. hassei (NOETLING 1885) Eocene, Samland, USSR1
A. latidens LERICHE 1908 Lwr Oligocene, Europe; Mid Miocene Europe & NC
A. latidens alabamensis WHITE 1956 Eocene, Alabama
A. leensis WARD 1978 Upper Eocene, England
A. superciliosus Middle Miocene, Europe & West Indies
Not included by Cappetta was A. grandis LERICHE 1942.
White (1956) described Alopias latidens alabamensis from the Eocene of Alabama. Case & Cappetta (1990) included this species from the Eocene of Egypt, but synonymized a similar tooth-design by Stromer (1903, Aprionodon frequens) with alabamensis (don't ask me why alabamensis had priority).
Kent (1994:71) considered only two species to be present in the Chesapeake Bay area (Oligocene-Pliocene): A. latidens from the Old Church, Calvert & Choptank (Oligocene-Miocene) and A. aff superciliosus from the Calvert (Miocene). Kent considered A. grandis but determined it most likely represented an upper lateral of "Isurus" hastalis.
In reporting this mid-Atlantic fauna, Müller (1999:42-43) identified his material as: A. exigua from the Belgrade Fm (Oligocene, NC) & basal Calvert (Miocene, VA), A. aff exigua Old Church (Oligocene, VA) and A. latidens from the Pungo River Fm (Miocene, NC) & Calvert (Miocene, MD).
When writing on the Lee Creek fauna (Mio-Pliocene, NC), Purdy et al (2001:107-108) rejected A. exigua and latidens on the basis of misidentifications and missing type material. Bob Purdy recognized that this material compared very well with extant taxa and they then went on to ascribe their material to the extant species A. superciliosus (Pungo River Fm, unit 3) and A. vulpinus (Pungo River 4-5 & Yorktown 1-2).
The observations of the above authors certainly suggest there is no consensus on western Atlantic (perhaps worldwide) determinations for this genus. Based on Leriche's images and tooth-design, there are certainly suggestions that exigua/superciliosus and latidens/vulpinus may each represent single lineages, However, there are differences and without a better idea of dentition-design it would be inappropriate to draw this conclusion. On this website, Paleogene material will follow Leriche (1910) as the benchmark and Neogene specimens will be compared with extant species as had Purdy et al (2001).
The Castle Hayne Formation is the only Palaeogene fauna, currently included on the website that reflects thresher shark teeth. The low & broad cusps and erect profile of these teeth compare well with Alopias latidens.
Included as what appears to be the A. latidens design is a tooth (Fig. ) from the Late Miocene of Japan.
At Lee Creek, individual teeth could not be confidently ascribed to a particular species based on the previously cited reports. To resolve this issue (using the author's collection), teeth (Q=c60) were first separated by horizon: Lee Creek 'tailings' (Pungo River units 4-6 and Yorktown2) and 'reject' (Pungo River units 1-3). Once separated, lateral profile was employed: group 'A' teeth included those with straight and 'B' lingually-directed cusps. This separation technique yielded two main groups of teeth from each horizon with distinct characteristics -- each group was present in the other horizon but in significantly different proportions.
A. cf superciliosus [Group 'A']. Upper Pungo River (4-6) material was predominated by larger teeth with broader & taller crowns which had labio-lingualy compressed erect cusps. This tooth-design compares very well with the extant broad-form (female) A. superciliosus. The narrow-form of these fossil teeth are not as common, but also compare well with extant superciliosus males (which have twisted/contorted cusps). Often lacking in these Pungo River specimens is the distinct nutrient groove seen in extant material; this is likely an issue of preservation, but warrants the "cf" notation. In the upper Pungo River sediments, Group 'A' teeth outnumbered "B' by 16 to 5. The author has collected similar teeth from the basal Calvert Formation of Virginia.
A. cf vulpinus [Group 'B'], Most common in Lower Pungo River units (1-3) were smaller teeth with narrower and shorter cusps that were lingually directed. These teeth, although the cusp was less broad, were much more A. vulpinus-like in design. They out numbered Group 'A' teeth by 20 to 8 in these units.
"Alopias" (aka Trigonotodus) grandis LERICHE 1942. Kent (1994: 71) trivialized and Purdy et al (2001) did not find examples of (Purdy pers. com. 2006) this taxon, but it appears to be a valid species preferring warmer and/or more pelagic waters than other fossil alopiids. Although apparently scarce in the Salisbury (MD/VA) & Albemarle (NC) Embayments, South Carolina horizons (Southeast Georgia Embayment) have yielded many examples reflecting multiple variations and tooth positions.
Kozlov (2001) described Trigonotodus alteri for enlarged cuspleted Alopias-like teeth from the Ashley Marl (Early Oligocene) of SC, based on the similarities with the much smaller T. tusbairicus KOZLOV 1999 (Middle Eocene, Kazakhstan). When erecting this genus, Kozlov (1999:157) included it as an otodontid; however, by 2001 it was included as an alopiid and he moved Alopias grandis to this genus. Lacking dentition-design details for either taxa this website will continue to attribute grandis-like teeth to "Alopias" and tentatively accept Trigonotodus for the Early Oligocene cuspleted design.
"Alopias" grandis teeth are highly enlarged versions of thresher teeth with a robust "C"-shaped root and lateral teeth with hooked cusps that bear a complete cutting-edge. No reconstruction of this dentition-design is known and its affinities to extant taxa cannot be fully established. Further blurring determinations is the similarities of some tooth-position designs with those of juvenile Parotodus. The ambiguities of these teeth lead to many questions, but large assemblages of them (as might be seen in some private collections) support a file-set distinct from Parotodus. According to Steve Alter (pers com 2006), in South Carolina grandis teeth can only be confidently ascribed to the Chandler Bridge Formation (Chattian, Late Oligocene) although they may be present in younger horizons. In more northern embayments they are known from Lower and Middle Miocene sediments.
In the Miocene of the western Atlantic there is another alopiid-like tooth-design but with a serrate cutting-edge. These scarce teeth are commonly referred to as A. (or T.) grandis, but appear to have a more erect distal cusp margin. Typically river-collected, they have been attributed to the Late Miocene in South Carolina and uppermost Calvert zones (Middle Miocene) of East-Central Virginia (Alter pers com 2006). A single well documented specimen can be confidently placed in the Serravalian (Middle Miocene) of the Salisbury Embayment.
Many of these genus pages can be constructed without help, but others require input from multiple contributors. This Alopias page required the input, perspectives, images, permission and/or comments of numerous individuals particularly: Steve Alter, Lutz Andres, Bill Counterman, Richard Curmi, Stephen Godfrey, Bill Heim, Gordon Hubbell, Peter Picard, Pieter De Schutter, David Ward and Pat Young.
||Leriche (1910: 287) wrote that the species A. hassei was established by means of one tooth from the Eocene of Samland. Leriche indicated that the tooth figured by Noetling closely resembles the upper lateral teeth of A. vulpes and that this one tooth is insufficient for characterising a species.|
||Only two specimens were recovered from Yorktown sediments (basal Unit 2) a horizon which often contains older material. Because these specimens appeared to be re-worked, they provide poor evidence for the presence of this taxon in the Pliocene at Lee Creek.|
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