The lower actinopterygian fauna from the Lower Carboniferous Albert shale formation of New Brunswick, Canada - a review of previously described taxa and a description of a new genus and species

This dataset contains the digitized treatments in Plazi based on the original journal article Mickle, Kathryn E. (2017): The lower actinopterygian fauna from the Lower Carboniferous Albert shale formation of New Brunswick, Canada - a review of previously described taxa and a description of a new genus and species. Fossil Record 20 (1): 47-67, DOI: 10.5194/fr-20-47-2017, URL: http://dx.doi.org/10.5194/fr-20-47-2017Abstract. The Lower Carboniferous Albert shale formation of New Brunswick, Canada, is well-known for the preservation of countless articulated lower actinopterygian palaeoniscoid fishes. This site is at the boundary between the Devonian and the Lower Carboniferous, making the lower actinopterygians preserved at this site important. The taxonomic history of previously described Albert shale formation actinopterygians is reviewed here. Many of the earliest described actinopterygian taxa from the Albert Formation are represented by poorly preserved type specimens and have the distinction of being moved from one paraphyletic genus to another paraphyletic genus. While these taxa are in need of major redescriptions, such work is premature until the large paraphyletic or polyphyletic genera they have been placed in, Palaeonicus[m], † Rhadinichthys, and † Elonichthys, are redescribed. But there is new diversity within the Albert shale formation. Here, a new lower actinopterygian species, † Lambeia pectinatus, is described from one well-preserved specimen. This new species is characterized by dorsal ridge scales with pectinated posterior margins, body scales inserted between adjacent dorsal ridge scales, body scales with pectinated posterior and ventral margins, the presence of a ventral rostro-premaxilla and a median rostral bone, a separate and distinct antorbital bone, and a single supraorbital bone. This newly described species is distinct from previously described fishes from the Albert Formation, and the morphology of this newly described species is more similar to later Carboniferous fishes rather than Devonian fishes. This suggests that morphological features commonly seen in Carboniferous fishes and rarely seen in Devonian fishes were present early in the Carboniferous.1 Introduction1.1 The Albert shale formationFor over 150 years, lower actinopterygian, or palaeoniscoid, fishes have been described from the Albert shales of southeastern New Brunswick, Canada (Fig. 1). The term Albert shales has been used informally to refer to the Albert shale formation, the middle formation of the Horton Group between the basal Memramcook Formation and the overlying Weldon Formation (Gussow, 1953; Greiner, 1962) (Fig. 2). Greiner (1962) and Utting (1987) present the Albert Formation itself as being composed of three members – the Dawson Settlement, Frederick Brook, and Hiram Brook members (Fig. 2). St. Peter (1993) presents the Albert Formation as being composed of six stacked lithofacies – conglomerate, sandstone, mudstone, mudstone/sandstone, kerogenous mudstone, and evaporate facies.Since the 1800s, there has been controversy over the age of the Albert Formation. While an Early Carboniferous age was supported by the fossil fish and plants (Bailey and Ells, 1878; Lambe, 1909, 1910), some cautioned that the Albert Formation could be Devonian in age (Bailey et al., 1880; Ells, 1903). This trend continued into the late 1900s. Greiner (1962, 1974) had originally described the Albert Formation as Lower Carboniferous in age, but after the description of an osteolepid, † Latvius porosus from basal beds, he considered the lower part of the Albert Formation to be Devonian (Greiner, 1977). Recent reassessments of the Albert Formation sarcopterygian material do not support Greiner’s assignment of the material to the Devonian genus † Latvius, but rather suggest megalichthyid and Carboniferous affinities (Miller and Brazeau, 2007). This, combined with spore analyses, has put an end to the controversy regarding the age of the Albert Formation. The Albert Formation is Tournaisian (Lower Carboniferous) in age, near the Devonian and Lower Carboniferous boundary (Utting, 1987; St. Peter, 1993; Miller and Brazeau, 2007).Figure 2. Stratigraphic column of the Lower Carboniferous of New Brunswick, Canada. Figure modified after Utting (1987, fig. 2).Figure 1. Map of locality. (a) Map of North America; box highlights area enlarged in (b). (b) Close up of New Brunswick, Canada. Dashed line indicates Albert County, where the majority of the specimens were collected. Black dot indicates Hillsborough, the site at which the original material described by Jackson was collected. Scale bar equals 50 km; (a) not to scale. Map modified from Google Maps, Map Data: ' 2015 Google.The Albert Formation is paleontologically famous for its countless articulated lower actinopterygian specimens (Greiner, 1977). These actinopterygians are important because with the supported Early Carboniferous age of the Albert Formation, they potentially bridge morphological gaps between Devonian and Carboniferous forms. Unfortunately, these fishes have not been dealt with in great detail for over a hundred years. The taxonomic history of the Albert Formation fishes is discussed here.1.2 Review of the taxonomic history of the Albert Formation palaeoniscoidsThe palaeoniscoid fishes from the Albert Formation of New Brunswick have been a taxonomic nightmare for over 150 years. Lambe (1909, 1910) provided a taxonomic history of these fishes in his redescription of some of the New Brunswick fishes. This information is reviewed and updated below.In 1851, Jackson described the first palaeoniscoid fishes from the Albert shales in papers entitled “Report on the Albert Coal Mine” (Jackson, 1851a) and “Descriptions of five new species of fossil fishes” (Jackson, 1851b). Though the second title claims to include the descriptions of five new taxa, only three new species were described and named – † Palaeoniscus [m] alberti, † P. brownii, and † P. cairnsii. Four additional specimens were described but never named. No type material was designated, and though plates and figures are referenced in this publication, they were never included with the text (Lambe, 1909, 1910).Eastman (1908) and Lambe (1910) concluded that though Jackson’s plates and figures were never published with the original descriptions, a few must have existed and been distributed to paleontologists because the plates were referenced by other scientists (see Traquair, 1877, p. 49; Dawson, 1877, p. 338). Dawson (1877) described two new palaeoniscoid species from the Albert Formation – † Palaeoniscus [m] modulus and † Palaeoniscus [m] jacksonii. Again, no type material was designated. Dawson (1877) also provided additional comments on Jackson’s original species and referenced particular specimens figured by Jackson (1851a, b).In the late 1800s and early 1900s, many scientists commented on how the Albert Formation palaeoniscoids were more similar to species within the genera † Rhadinichthys and † Elonichthys. As detailed by Lambe (1910), Traquair (1877) commented that † Palaeoniscus [m] alberti and † P. cairnsii are closely allied to † Rhadinichthys carinatus (Agassiz). This reassignment was later upheld by Traquair (1911). Traquair (1877) referred † Palaeoniscus [m] brownii to † Elonichthys brownii. Newberry (1899) upheld Traquair’s (1877) reassignments. In Woodward’s catalogue (1891), † Palaeoniscus [m] alberti, † P. cairnsii, and † P. modulus were referred to † Rhadinichthys alberti, † R. cairnsii, and † R. jacksoni (1891). Woodward (1891) also assigned † Palaeoniscus [m] brownii to † Elonichthys brownii, but also noted that he felt this was a “doubtful” and illdefined species (Lambe, 1910). Eastman (1908) also referred the New Brunswick species to the genera † Rhadinichthys and † Elonichthys. In the same publication, Eastman described a new species from the Albert shales – † Elonichthys elegantulus – but no type specimen was designated (1908). All of the reassignments by Traquair (1877), Newberry (1889), Woodward (1891), and Eastman (1908) were done without justifications for these reidentifications.Sometime before 1908, Jackson’s original unpublished plates were discovered by Eastman in the Yale Peabody Museum (Eastman, 1908; Lambe, 1910). Using these plates, it was possible for Lambe (1909, 1910) to identify some of Jackson’s original type and figured specimens in the collections of the Museum of Comparative Zoology, Harvard, and the Boston Society of Natural History. Using this new information, Lambe (1909, 1910) was able to redescribe the Albert Formation fishes and describe a new taxon, † Elonichthys ellsi. Agreeing with Traquair (1877, 1911), Woodward (1891), and Newberry (1908), Lambe (1909, 1910) referred † Palaeoniscum alberti to † Rhadinichthys alberti and † P. brownii to † Elonichthys brownii. Lambe (1909, 1910) also determined that † Palaeoniscum cairnsii (Jackson, 1851a, b) was not a valid species, nor was † Elonichthys († Palaeoniscum) jacksoni (Dawson, 1877). Lambe (1909, 1910) also referred † Palaeoniscum modulus (Dawson, 1877) to † Canobius modulus, and the validity of † Elonichthys elegantulus (Eastman, 1908) was called into question.Reassignments of Albert shale fishes continued in the later 1900s. Moy-Thomas (1938) commented that Westoll considered † Canobius modulus to be † R. alberti and agreed with Westoll that † C. modulus is synonymous with † R. alberti. Sternberg (1939) studied newly collected specimens from the Albert Formation and assigned these specimens to † R. alberti. Sternberg (1939) cautioned though that there were differences in measurements and ratios between the specimens designated as † R. alberti, suggesting that there is more than one species within this taxon or that the species is characterized by a great degree of variation. Gardiner commented on the Albert Formation fishes in his catalog of Canadian fossil fishes (Gardiner, 1966). Miller and McGovern (1996) published a prelim

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.