Early Eocene fish otoliths from the eastern and southern USA

. A collection of 1149 otoliths of the Ypresian and Ypresian–Lutetian transition (early Eocene) from 18 sites across five states in the eastern and southern regions of the USA was analyzed. In total, 33 otolith-based taxa are documented, of which 27 are identified at the species level. Nine of these are introduced as new species: “ Conger ” biaculeatus sp. nov., Bauzaia gibbosa sp. nov., Ampheristus brevicaudatus sp. nov., Symmetrosulcus virginicus sp. nov., Neobythites longesulcatus sp. nov., “ Neobythites ” pamunkeyensis sp. nov., “ Neobythites ” stringeri sp. nov., Waitakia dorsogibbosa sp. nov., and “ Haemulon ” ypresiensis sp. nov. The assemblages are distinct when compared to their younger Eocene counterparts in America. This distinction is primarily characterized by the high proportion of the newly introduced species or exclusive Ypresian species. Additionally, we highlight the presence of 10 amphi-Atlantic species originally described in European deposits. Significantly, the composition of the otolith collection supports the interpretation of a shallow-water environment for the sampled sites during the Ypresian. This ecological setting appears to persist into the subsequent middle and late Eocene within the same geographic region.


Introduction
In a previous monograph (Lin & Nolf 2022), we provided a comprehensive account of all available knowledge on middle and late Eocene otoliths from the Atlantic side of the USA, encompassing both the Atlantic and Gulf Coastal Geologic plains.In the present study, we present the early Eocene counterpart of this work, which focuses on the Ypresian otoliths.Both studies combined provide a comprehensive Nielsen (1985) (later updated in Agnini et al. 2014).He concluded that the lowest occurrence of the calcareous nannofossil species Blackites inflatus (Bramlette & Sullivan, 1961) is at the top of the lower third of the Reklaw Formation (Jiang 1998: 859, fig.2).This nannofossil event marks the base of the Lutetian Stage as originally defined by the Global Stratotype Section and Point (GSSP) at Gorrondatxe (Spain) (Molina et al. 2011;Speijer et al. 2020).This means that only the lower portion of the Reklaw Formation belongs to the Ypresian, but that the main part of it is Lutetian in age.(Fig. 2).Jiang (1998: fig.2) also suggested that it took about 1.7 Myr to deposit the Reklaw Formation, from about 48.4 Ma to about 46.7 Ma, if the data are converted to the time scale of Speijer et al. (2020).However, it must be noted that this indicative timeframe is difficult to assess on the basis of the available information.Sams & Gaskell (1998: figs 4-5) noticed around the same time that the lithostratigraphy of the Reklaw Formation is very complex.There is an increasing complexity in basinward direction, due to a series of distinct sand bodies which developed within the predominantly silty succession.The conclusions of a calcareous nannofossil dating of four separate locations by Sams & Gaskell (1998: 315) (among which the Bastrop County area where the Ridge Creek sample was collected) were far from decisive, as it suggested a possibly assignment to nannofossil zones CP11, CP12 or even CP 13.This nannofossil interval covers a very large time span (about 4 Myr according to Agnini et al. 2014, from about 50 Ma to 46 Ma), which extends far below and above the Ypresian/Lutetian boundary, dated at 47.84 Ma according to Payros et al. (2015).As to date we are unable to clarify the exact position of the studied otolith samples, we prefer to consider the Reklaw Formation as part of the Ypresian-Lutetian transition.4) Agnini et al. (2014).
However, on top of these uncertainties arises the question of the placement of the GSSP for the base Lutetian, which was recently contested by Steurbaut & Nolf (2021) (see caption of Fig. 2).Based on a high-resolution biostratigraphic comparison between the GSSP at Gorrondatxe (Spain), Belgium and the historical Lutetian stratotype in the Paris Basin, they suggested that the golden spike had been placed 130 m too high at Gorrondatxe.It should be lowered down to a level predating the internationally accepted GSSP by about 1.3 Myr, estimated at about 49.11 Ma (Steurbaut & Nolf 2021), instead of the 47.76 Ma date initially proposed by Molina et al. (2011).
Sediment: coquina with grey green sandy matrix.
Available material: bulk samples collected by D. Nolf (ca 30 kg).
Available material: additional otoliths provided by C. Garvie.
Sediment: the Hatchetigbee Bluff section shows a very heterogeneous lithological succession.The lowest visible part at the time of the visit consisted of brownish-green, clayey sand with a Venericardia Lamarck, 1801 coquina, followed by (in ascending order): 2.3 m of finely stratified organic clay; about 1.20 m of green sand, the lower part of which protrudes markedly from the bluff; at least 2 m (upper part not well exposed) of organic clay; and, finally, a layer of green clayey sand with coquina levels of broken shell material.
Available material: sample 13a (ca 100 kg, sampled by D. Nolf in 1987) from the upper coquina in green clayey sand and some additional separate otoliths from the same level, provided by G. Stringer; sample 13b (ca 50 kg, sampled by D. Nolf in 1987) from the middle protruding sand bed; sample 13c (ca 50 kg, sampled by D. Nolf in 1987) from the Venericardia coquina, which was devoid of otoliths, but was used for calcareous nannofossil analysis.
Sediment: coarse grey to reddish-brown glauconitic sand with many shells, exposed below a well marked level of large sandstone concretions.
Available material: bulk samples collected by D. Nolf in 1987 (ca 25 kg) and additional otoliths provided by D. Dockery.
Stratigraphy: Reklaw Formation, unnamed member at top of Marques Shale Member, Ypresian-Lutetian transition (see Material and methods).
Available material: additional surface collecting otoliths provided by C. Garvie.
Available material: 30 kg from lowest Venericardia level, taken by D. Nolf in 1989; no otoliths, but the sample was used for calcareous nannofossil analysis.

Etymology
The species name biaculeatus alludes to the acuminated anterior and posterior rims of the otoliths.

Description
The newly described species "C." biaculeatus sp.nov. is characterized by oval-shaped otoliths with pointed anterior and posterior rims.The otoliths are moderately thick and have smooth margins, with slightly convex inner and outer faces.The deepest part of the otoliths is in their central part, where the ventral rim is slightly angled.The sulcus is wide and not well-divided into ostium and cauda, opening antero-dorsally on the anterior rim.A large colliculum fills the sulcus, which is more visible in the cauda.The ostial crista superior curves markedly upwards, and the caudal cristae are well-developed.The cauda is short, straight, and ends well before the posterior rim, while the crista inferior is almost straight without constriction.The size of the ventral area is comparable to the dorsal one.

Remarks
The sulcus type of "C." biaculeatus is similar to that of other species under the incertae sedis genus, such as "C." prolatus and "C." websteri in Lin & Nolf (2022: figs 12d-g, 13a-c), which suggests that it may belong to an extinct taxon within the family Congridae.

Type locality and horizon
United States of America, Loyola Retreat House, N of Popes Creek (Maryland), Woodstock Member.

Description
The otoliths are thick and rounded, with a salient, pointed posterior end.The inner face is convex and the outer face is strongly concave.The margins are smooth.The sulcus is straight, broad, and reaching, but not opening, to the margins of both anterior and posterior rims.It is divided into an elongate ostium and a very short cauda, which is rectangular and slightly pointing downwards.The ventral area is markedly large, semicircular and forming the general shape of the otoliths.

Remarks
The otolith characters of the new species, Bauzaia gibbosa sp.nov., display a mix of those seen in the other two congeneric species, B. mucronata (Koken, 1891), and B. lamberi Dante & Frizzell, 1965, but differ from them by lacking the notable antero-dorsal bulging expansion of the dorsal rim.The appearance and shape of the otoliths of B. gibbosa are most similar to those of B. lamberi, but the former has a sulcus type resembling that of B. mucronata, especially the rectangular shape of the cauda.The new species is very rare and only known from the type locality.

Stratigraphic and geographic distribution
Ypresian: Woodstock Member, Maryland.

Etymology
'Brevicaudatus, a, um' = 'having a short cauda'.Refers to the very small and short cauda.

Type locality and horizon
United States of America, Rappahannock River (Virginia), Potapaco Member.

Description
This species has fusiform otoliths with a postero-ventral angle that is extended.While the holotype has a pointed angle (Fig. 6D), it is typically blunt in other specimens (probably a result of abrasion).The margins are smooth, but may be slightly lobated in some specimens along the anterior and posterodorsal rims (Fig. 6F).The antero-dorsal rim is slightly elevated, but not protruding dorsally, while the anterior rim forms a large, obtuse rostrum.The inner face is slightly convex; the outer face is concave posteriorly, but may be slightly convex anteriorly.The sulcus is well-divided into an elongate ostium and a very short, much narrower cauda that points downwards.Both the ostium and cauda are filled with a colliculum each.The ventral area is of similar size to the dorsal area.There is a shallow, elongate dorsal depression above the crista superior.

Remarks
Otoliths of Ampheristus are mainly known from Paleogene European deposits (Nolf 2013), with two species from the Lutetian of New Zealand (Schwarzhans 2019).The first record of the genus from the New World region is Ampheristus americanus Schwarzhans & Stringer, 2020, a recently described

Description
The otoliths of this new species are elliptical in shape, with a blunt anterior rim and a well-marked posterior angle.The dorsal and ventral rims are gently curved, and their deepest part is in the middle of the otoliths, giving them a regular, rounded appearance.All margins are smooth, and the otoliths are considerably thick, with both the inner and outer faces being convex (Fig. 7C1).A straight, wide, and well-divided sulcus occupies nearly the entire length of the inner face and is located in the central zone of the otoliths.The ostial and caudal parts are each fully filled by a colliculum.The ostium reaches the anterior margin, while the cauda extends backward to the origin of the posterior angle but does not reach the posterior margin.The cauda is slightly shorter than the ostium.The ventral area is of similar size as the dorsal one.

Remarks
The general shape of the otoltihs and the caudal type of this new species are similar to those of Symmetrosulcus meyeri (Koken, 1888) (see Lin & Nolf 2022: fig.18a-f), whereas the thickness of the otoliths is similar to that of the otoliths of Preophidion, such as P. elevatus (Koken, 1888) and P. granus (Müller, 1999).However, the otoliths of the new species exhibit a concavity on the postero-ventral rim, and its sulcus is much wider than that of S. meyeri.On the other hand, the cauda of the new species does not bend as strongly as that of Preophidion.The sulcus of the new species suggests that it is more similar to Symmetrosulcus than to Preophidion.

Etymology
'Longesulcatus, a, um' = 'provided with a long sulcus'.Refers to the notably elongate sulcus of the species.

Description
The species is identifiable by its fusiform otoliths, which have a largely blunt anterior rim and a wellmarked posterior angle.The dorsal rim is elevated and possesses a blunt antero-dorsal bulge, forming the highest point of the otoliths.The ventral rim is gently curved, and all margins are smooth.The otoliths are thick and possess convex inner and outer faces (Fig. 8A1).A straight, wide, and well-divided sulcus occupies nearly the entire length of the inner face in the central region of the otoliths.The sulcus does not open to the margins.The ostium is notably elongate and extends over one-third of the sulcus length, and it is very slightly narrower than the short, rectanglar cauda.Above the crista superior, there is a shallow, elongate dorsal depression.

Remarks
The massive, robust otoliths of this new species share many characters with those of "Neobythites" auribatianus Lin et al., 2017, from the Lutetian of the Aquitaine Basin (Lin et al. 2017b: fig.9a-g), indicating a possible close relationship.Nevertheless, the American species is distinguished by its less pronounced blunt antero-dorsal bulge, more rounded anterior rim, less tapered posterior rim, and somewhat broader sulcus.Moreover, the high resemblance of the sulcus shape and proportions (e.g.OL/ sulcus length, OsL/CaL) and the overall configuration with otoliths of Neobythites allow us to assign this new species to this extant genus (see Lin & Chang 2012: pl.81).

Type locality and horizon
United States of America, Pamunkey River, Hanovertown (Virginia), Potapaco Member.

Description
The otolith of this species is characterized by an oval to squarish outline with a prominent postero-dorsal angle.The dorsal rim is nearly flat, and and the ventral rim is gently curved.The anterior rim is rounded, and the posterior rim is largely blunt.All margins are smooth.The otoliths are thick, with both the inner and outer faces convex (Fig. 7G1).A straight, elongate, and undivided sulcus sits in the central zone of the otolith.The sulcus does not open to the margins.The posterior part of the sulcus is slightly wider than the anterior part and very slightly bent downward at the tip.The ventral area is of similar size as the dorsal one.

Remarks
This species is solely represented by a single specimen from the type locality.The bizarre outline and undivided sulcus are a unique character combination that does not resemble any known otolith-based species.

Etymology
This species is dedicated to Gary L. Stringer (University of Louisiana at Monroe) for his major contributions to the knowledge of the fossil otoliths from the USA.

Paratypes (3 in total)
UNITED STATES OF AMERICA • 3 otoliths of which one is figured: Fig. 8D; same collection data as for holotype; IRSNB P 10748.

Type locality and horizon
United States of America, Hatchetigbee Bluff (Alabama), Hatchetigbee Formation.

Description
This species is characterized by robust and fusiform otoliths that bear a blunt antero-dorsal bulge, forming the highest and thickest part of the otoliths in the anterior portion (Fig. 8E1).The otoliths taper in the posterior part and end with a pointed tip.The ventral rim is regularly curved.The inner face is convex; the outer face is essentially flat, becoming thinner towards the ventral and posterior rims.The sulcus occupies nearly the entire length of the inner face and is constituted by a long, horizontal ostium and a very short, downward-bent cauda.A shallow dorsal depression is observed above the central part of the crista superior.The ventral area is slightly larger than the dorsal one.

Remarks
At first glance, the otoliths of "N." stringeri sp.nov.are very similar to those of N. longesulcatus sp.nov.(see above), but they can be distinguished by the short, strongly bent cauda and larger ventral area in the former species."Neobythites" stringeri is only known form the type locality.

Etymology
'Dorsogibbosus, a, um' = 'hump bearing on the dorsal part'.Refers to the angulous and humpy dorsal part of the otoliths.

Type locality and horizon
United States of America, Pamunkey River, Hanovertown (Virginia), Potapaco Member.

Description
This species is characterized by small, trapezoid to triangular otoliths, with dorsal and ventral rims approximately parallel to each other and oblique anterior and posterior rims.The dorsal rim is very short, bears a strong postero-dorsal angle, and its anterior part is inclined downwards.The ventral rim is gently curved and bears an angle at each end.The thickness of the otoliths is most considerable in the middle, with both the inner and outer faces being convex (Fig. 9F1).The sulcus is well-divided into ostium and cauda, marked by a constriction of the cristae in the central zone of the sulcus.The ostium is wide, arrow-like, with a low ostial lobe expanding ventrally and tilting towards the antero-ventral rim, and its anterior tip nearly reaches the anterior rim of the otolith.The cauda is rod-like, horizontal, and shows a rounded posterior end.There is no trace of a swollen collicular crest on the caudal crista inferior like in gobiids.A dorsal depression is observed above the well-developed caudal crista superior.

Remarks
The otoliths of W. dorsogibbosa sp.nov.resemble most to those of Waitakia beelzebub Lin & Nolf, 2022 from the middle to late Eocene (Lutetian-Bartonian) of the southern USA and other congeners from the Eocene of New Zealand.The thick profile and sulcus morphology are characteristics for assigning the new species to the fossil genus Waitakia.However, W. dorsogibbosa has the shortest dorsal rim exhibiting a triangular outline.The species may represent one of the earliest records of this extinct lineage.It is extremely rare with only two specimens in our material.

Stratigraphic and geographic distribution
Ypresian: Potapaco Member, Virginia and Maryland.

Type locality and horizon
United States of America, Pamunkey River, Hanovertown (Virginia), Potapaco Member.

Description
This species is distinguished by oblong otoliths with crenulated margins and a moderately thick build.The inner face is convex and the outer face is concave.The sulcus is clearly devided with crest-like cristae forming a deep incised sulcus.The ostium opens widely and antero-dorsally, and an expansion is present at the ostial lobe.The junction of the ostial and caudal crista inferior is located more posteriorly with respect to the same junction in the crista superior.The cauda is straight for about two-thirds of its length and markedly bent ventrally at the posterior end.The dorsal area is narrower than the ventral one.There is a shallow dorsal depression located just above the crest-like caudal crista superior.

Remarks
The otoliths of "H." ypresiensis sp.nov.are most similar to those of "Haemulon" pulchrum (Frost, 1934) and "Haemulon" obliquum (Müller, 1999), based on their sulcus and outline shape."Haemulon" pulchrum is a widely distributed Eocene European species, and the otoliths of the new species resemble those from the Lutetian of Osteroden, Germany (see Schwarzhans 2007: fig. 32;Lin et al. 2017b: fig. 12h-l).However, the dorsal rim of the new species is flat, whereas in "H." pulchrum, it is notably elevated and forms the highest part of the otoliths.On the other hand, "H." obliquum, a middle to late Eocene American species (see Lin & Nolf 2022), has otoliths that are more similar to the new species, with the largest difference being that the cauda tip extends further backwards and is more markedly bent, reaching almost to the posterior rim of the otoliths.

Remarks on taxa requiring comments
Ariosoma sp.
Fig. 4A A single Ariosoma otolith was recovered from the Bashi Formation, Mississippi (Table 1).The otolith differs from the common species of Ariosoma, A. nonsector Nolf & Stringer, 2003, by having a flatter dorsal rim, but we retain our identification due to the lack of sufficient specimens.
Albula meridiana (Frizzell, 1965) Fig. 3C-D The otoliths are elongate to rectangle in shape, with a cauda that is bent downward and a nearly flat dorsal rim that ends with a weak postero-dorsal angle.Albula meridiana was originally described as Eoalbula meridiana by Frizzell (1965), and later assigned to the "genus Albulidarum" by Nolf (1985) and remained as such in the following literature (Müller 1999).However, the species remains doubtful (Nolf 2013) and requires further study as suggested by Nolf & Dockery (1993).Frizzell's taxonomic acts were questionable, as they were mainly based on poorly-preserved or juvenile specimens, and his otolith-based genera were forced to reveal tentative evolutionary lineages.Despite this, based on their distinct characters, the three better-preserved otoliths described in this study can be confidently assigned to this species.Albula meridiana is only known from the Bashi Formation of Mississippi.
Ariidae indet.Fig. 5F Based on the poor preservation and lack of distinct features, the ariid otoliths in the collection could not be confidently identified to the species level and are therefore assigned as Ariidae indet.The lack of common occurrence of ariid otoliths in the studied localities could indicate a low abundance of ariids.
"Merluccius" papillosus (Stinton, 1966) Fig. 5D We assign a medium-sized otolith from the Rappahannock River, Virginia, to "M." papillosus based on distinct features, including an obtuse rostrum, relatively flat dorsal and ventral rims, a wide and pincenez-shaped sulcus, and an upward-oriented ostium.Although about one-third of its posterior part is not preserved, we deem these characteristics to be sufficient for identification.The species is known from Lutetian European deposits, including the English Hampshire Basin, Belgian Basin, and NW Germany (Osteroden) (Lin et al. 2017b).This specimen represents the first occurrence of "M." papillosus in the Americas.
"Neobythites" constrictus Stinton, 1977 Fig. 7B An oblong otolith from the Rappahannock River locality in Virginia possesses an obtuse, moderately protruding rostrum and a sulcus type most similar to "N." constrictus from the Ypresian London Clay of southern England.The more compact outline of the otolith and flatter inner face are considered as size-related intra-specific variability.
Preophidion arcuatus (Stinton, 1966) Fig. 9A-C Otoliths belonging to this species are commonly found in the Bashi and Hatchetigbee formations and share several distinctive characteristics with those of P. arcuatus from the Ypresian London Clay, as described by Stinton (1966) under the name Brotula arcuatus.The general outline of the otoliths, as well as the downward-bent cauda, suggest that this species can be assigned to the fossil genus Preophidion.

Discussion
The otolith collection described here consists of 1149 otolith specimens, which were assigned to 33 different taxa from 17 families (Table 1).Of these taxa, nine species were newly described.The highest number of otoliths were found in the Bashi Formation in Mississippi (308 otoliths) and Alabama (296 otoliths), each containing 11 taxa.The Potapaco Member in Virginia had the highest taxonomic richness with 15 taxa and 156 otoliths, including several new ophidiid species.The Hatchetigbee Formation in Alabama (246 otoliths) and the Reklaw Formation in Texas (124 otoliths) also yielded moderately rich and abundant assemblages with 12 and 11 taxa, respectively.Although the otolith assemblages from the Potapaco and Woodstock members in Maryland were small (only eight and 11 otoliths, respectively), they still contained four and six taxa, respectively (Table 1).
The dominant taxa within the collection are the Ophidiidae, Congridae, and Haemulidae (Table 1).The collection lacks any representation of mesopelagic and bathybenthic fishes, which strongly implies that the sampled sites were situated in shallow-water environments.This finding is consistent with the notion of a persistent shallow, neritic environment that likely prevailed in the younger middle and late Eocene of America (Lin & Nolf 2022).
Figure 11 shows the stratigraphic distribution of the currently known 28 nominal otolith-based species recorded from the American Ypresian and Ypresian-Lutetian transition (27 identified herein and one, namely Symmetrosulcus meyeri, mentioned by Ebersole et al. 2019).Among these, nine newly described species are exclusively known from the early and middle Ypresian, specifically occurring in Zones NP 10 to base NP 13.Notably, the stratigraphic range of Orthopristis burlesonis, originally documented from Burleson Bluff (Lutetian), has now been extended downward to the early Ypresian, persisting until the Bartonian.Furthermore, we have identified 10 amphi-Atlantic species, initially described from European deposits, and their American range is shown (Fig. 11).This further contributes to the understanding of trans-Atlantic faunal connections during this period.
In the Reklaw Formation, representing the Ypresian-Lutetian transition, the emergence of certain species is evident, and these persist in subsequent deposits where they become more distinctly characteristic.Specifically, we have identified small specimens that appear to be juveniles of Bauzaia mucronata, Lactarius kokeni, and Anisotremus rambo, species of which the adults have been found in a large number of Lutetian and Bartonian deposits (Lin & Nolf 2022).Within the Hatchetigbee Formation in Alabama, we have recovered a single otolith of the sciaenid species Ekokenia eporrecta, marking one of the earliest confirmed records of the Sciaenidae family with species assignment.Ekokenia eporrecta is a common to abundant species across all Claibornian localities in the southern USA (Frizzell & Dante 1965;Ebersole et al. 2019;Lin & Nolf 2022).Its common occurrence in the Reklaw Formation, representing the Ypresian-Lutetian transition, is not unexpected given its abundance and wide geographic distribution in the Claibornian (? top Ypresian to middle Priabonian).But, its early appearance in lower-Ypresian strata is quite surprising, although entirely in line with the paleogeographic distribution pattern of Ekokenia eporrecta, which is restricted to the US Atlantic and Gulf coastal plains.Additionally, Nolf (1995) reported a worn sciaenid otolith from the slightly older Bashi Formation in Mississippi, which could not be identified to the species level.These findings collectively suggest the initial presence of Sciaenidae in the early Eocene, and the potential for additional records in lower Eocene strata.It is noteworthy that sciaenids gradually increase in importance in Lutetian deposits of America and become a dominant group in Bartonian and subsequent younger strata (Lin & Nolf 2022).Interestingly, sciaenids are conspicuously absent from the European Eocene record and their occurrences only becomes widespread in the Neogene.In Appendix 1, we present a comprehensive dataset indicating the presence or absence of nominal otolithbased species from the American Eocene.This dataset allows for a broader-scale comparison of otolithbased fauna between the Atlantic and Gulf coastal plains, encompassing a total of 99 known species to date.In comparison to the extensive collection documented in middle and upper Eocene deposits by Lin & Nolf (2022), it is evident that the Ypresian collection appears relatively smaller both in terms of abundance and species diversity due to lower sampling effort (Table 1).However, the Ypresian collection remains noteworthy due to the substantial proportion of unique taxonomic composition it possesses.To be precise, out of the 28 nominal species identified, a remarkable 15 of them are either newly described or confined exclusively to the lower and middle Ypresian strata.This distinctive characteristic sets these assemblages apart from the otolith-based faunas found in the younger Eocene deposits.

Fig. 11 .
Fig. 11.Distribution of the currently known 28 nominal otolith-based species from the Ypresian and Ypresian-Lutetian transition of the eastern and southern USA, arranged according to their first appearance and stratigraphic ranges.This includes Symmetrosulcus meyeri (Koken, 1888) from the Tallahatta Formation (Ebersole et al. 2019) and 27 nominal species described in the present study.

Table 1
(continued on next page).An overview of otolith-based fish taxa from the Ypresian (early Eocene) of the Atlantic and Gulf coastal plains.Fossil genera are underlined.Number of identified specimens are indicated in each studied stratum.

otolith taxa from the early Eocene of eastern and southern USA Mississippi Alabama Virginia Maryland Texas
Table 1 (continued).An overview of otolith-based fish taxa from the Ypresian (early Eocene) of the Atlantic and Gulf coastal plains.Fossil genera are underlined.Number of identified specimens are indicated in each studied stratum.