Hostname: page-component-74656f9884-c52kr Total loading time: 0 Render date: 2026-11-07T18:21:40.610Z Has data issue: false hasContentIssue false
  • English
  • Français

Oldest parastacid molariform fossils from South America: Maastrichtian record from northern Patagonia, Argentina

Published online by Cambridge University Press:  23 October 2026

Nicolas Roberto Chimento Open the ORCID record for Nicolas Roberto Chimento [Opens in a new window] ,
Federico L. Agnolin ,
Karen M. Panzeri ,
Sergio Bogan ,
Michael Archer ,
Trevor H. Worthy ,
Nahuel Vega  and
Agustin G. Martinelli
Nicolas Roberto Chimento*
Affiliation:
Laboratorio de Anatomia Comparada y Evolucion de los Vertebrados, Museo Argentino de Ciencias Naturales Bernardino Rivadavia , Argentina Museo de Ciencias Naturales y Arqueología “Prof. Manuel Almeida”, Fundación de Historia Natural “Félix de Azara” , Argentina
Federico L. Agnolin
Affiliation:
LACEV, Museo Argentino de Ciencias Naturales Bernardino Rivadavia , Argentina Departamento de Ciencias Naturales y Antropología, Fundación de Historia Natural “Félix de Azara” , Argentina
Karen M. Panzeri
Affiliation:
División Ictiología, Museo Argentino de Ciencias Naturales Bernardino Rivadavia , Argentina
Sergio Bogan
Affiliation:
División Ictiología, Museo Argentino de Ciencias Naturales Bernardino Rivadavia , Argentina
Michael Archer
Affiliation:
School of Biological, Earth & Environmental Sciences, University of New South Wales , Australia
Trevor H. Worthy
Affiliation:
College of Science and Engineering, Flinders University , Australia
Nahuel Vega
Affiliation:
Laboratorio Argentino de Haces de Neutrones, Comisión Nacional de Energía Atómica , Argentina
Agustin G. Martinelli
Affiliation:
Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales Bernardino Rivadavia , Argentina
*
Corresponding author: Nicolas Roberto Chimento; Email: nicochimento@hotmail.com
Rights & Permissions [Opens in a new window]

Abstract

The fossil record of freshwater crayfishes (Astacoidea and Parastacoidea) is globally scarce and dominated largely by trace fossils and bio-gastroliths, particularly in Gondwana. In South America, Mesozoic records have been restricted to ichnofossils, with unequivocal body remains known only from the Paleogene. Here we describe isolated mandible cephalic molar fields attributable to Parastacidae from the Maastrichtian Los Alamitos Formation of northern Patagonia, Argentina. These specimens, recovered from historical collections of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” and previously misidentified as vertebrate teeth, represent the oldest confirmed parastacid body fossils from South America and the second Cretaceous record of the clade in the Southern Hemisphere. The material consists of five incompletely preserved molariform structures, including one nearly complete cephalic molar field, exhibiting a distinctive combination of features such as a subrectangular outline, prominent lateral cusps, a longitudinal central depression, and a thick enamel-like apatite coating. Comparative analysis indicates that these remains cannot be referred to any extant South American genus and likely represent a distinct, unnamed parastacid lineage, possibly showing closer affinities to Malagasy taxa. The Patagonian record reported here fills a critical temporal gap between Early Cretaceous parastacids from Australia and Paleogene records from South America and Australasia, supporting a widespread Gondwanan distribution of parastacids during the Late Cretaceous and reinforcing hypotheses of early high-latitude diversification followed by subsequent dispersal.

Information

Type
Articles
Information
Journal of Paleontology , First View , pp. 1 - 8
Check for updates
Copyright
© The Author(s), 2026. Published by Cambridge University Press on behalf of Paleontological Society

Non-technical Summary

Freshwater crayfishes are common animals in rivers and lakes today, but their fossil record is very limited, especially in the Southern Hemisphere. In South America, evidence of these crustaceans during the Mesozoic Era has been restricted almost entirely to fossil burrows, with actual body remains known only from much younger rock layers. This has made it difficult to understand when and how freshwater crayfishes first diversified on the continent. In this study, we report the oldest confirmed body fossils of freshwater crayfishes from South America. The fossils come from rocks dating to the very end of the Cretaceous Period (about 70 million years ago) in northern Patagonia, Argentina. They consist of small, tooth-like grinding structures from the mouthparts of crayfishes, which were originally misidentified as vertebrate teeth in museum collections. Careful reexamination shows that these remains belong to parastacid crayfishes, a group that today lives only in the Southern Hemisphere. These fossils represent the earliest confirmed record of parastacid crayfishes in South America and only the second known Cretaceous occurrence of the group in the Southern Hemisphere. Their age and geographic position help fill a major gap between older fossils from Australia and younger records from South America and Australasia. The distinctive shape of the Patagonian specimens also suggests that they may belong to an extinct lineage not represented among living South American species. Overall, this discovery provides new insight into the ancient distribution of freshwater crayfishes and supports the idea that these animals were already widespread across Gondwana during the Late Cretaceous, long before the final breakup of the southern continents.

Introduction

Crayfishes, freshwater crustaceans of the clade Astacidea, which also contains the marine lobsters, have a relatively poor fossil record worldwide (Feldmann et al., Reference Feldmann, Schweitzer and Leahy2011; Audo et al., Reference Audo, Hasiotis and Kawai2023). In the Southern Hemisphere, freshwater crayfishes are represented exclusively by the superfamily Parastacoidea, which contains one family, Parastacidae, which is the sister lineage to the Northern Hemisphere Astacoidea containing Astacidae, Cambaridae, and the East Asian Cambaroididae (Hasiotis, Reference Hasiotis2002; Crandall and Buhay, Reference Crandall and Buhay2008; Crandall and de Grave, Reference Crandall and de Grave2017). Together, these Northern and Southern Hemisphere clades form reciprocally monophyletic lineages with a deep divergence estimated to have occurred during the late Paleozoic to early Mesozoic (Bracken-Grissom et al., Reference Bracken-Grissom, Ahyong, Wilkinson, Feldmann and Schweitzer2014; Wolfe et al., Reference Wolfe, Breinholt, Crandall, Lemmon, Lemmon, Timm, Siddall and Bracken-Grissom2019). Parastacidae is a Gondwanan group currently distributed across freshwater environments in South America, Madagascar, Australia, New Zealand, and New Guinea but so far unknown from Africa and Antarctica. The fossil record of parastacids in Gondwana is sparse and uneven. The oldest confirmed body fossils are known from the Early Cretaceous of Australia (Bell et al., Reference Bell, Bicknell and Smith2020), with possible parastacoid-related trace fossils extending back to the Jurassic. In South America, and particularly in Argentina, the Mesozoic record consists solely of trace fossils, whereas body remains appear only in Paleogene deposits.

Throughout the Southern Hemisphere, most of the crayfish fossil record comprises traces (e.g., burrows) and bio-gastroliths (Hasiotis, Reference Hasiotis2002; Bedatou et al., Reference Bedatou, Melchor, Bellosi and Genise2008; Martin et al., Reference Martin, Rich, Poore, Schultz, Austin, Kool and Vickers-Rich2008; Toon et al., Reference Toon, Pérez‐Losada, Schweitzer, Feldmann, Carlson and Crandall2010; Panzeri et al., Reference Panzeri, Bogan, Raigemborn, Pagani, Chimento, Agnolín and Martinelli2024; Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025), with only a few documented body fossils (Aguirre-Urreta, Reference Aguirre-Urreta1992; Martin et al., Reference Martin, Rich, Poore, Schultz, Austin, Kool and Vickers-Rich2008; Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025). Consequently, the evolutionary history and biogeographic patterns of Gondwanan crayfishes remain poorly understood (Martin et al., Reference Martin, Rich, Poore, Schultz, Austin, Kool and Vickers-Rich2008; Feldmann et al., Reference Feldmann, Schweitzer and Leahy2011; Bell et al., Reference Bell, Bicknell and Smith2020).

One of the most outstanding features of parastacid anatomy is the occurrence of mandibles having “molar ridges,” which are convergent on some vertebrate teeth in terms of shape, function, and anatomy (Tynyakov et al., Reference Tynyakov, Bentov, Abehsera, Khalaila, Manor, Katzir Abilevich, Weil, Aflalo and Sagi2015; Bentov et al., Reference Bentov, Zaslansky, Al-Sawalmih, Masic, Fratzl, Sagi, Berman and Aichmayer2012, Reference Bentov, Aflalo, Tynyakov, Glazer and Sagi2016; Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025). These molariform structures are adapted to withstand abrasion during food processing. In extant species such as Cherax quadricarinatus (von Martens, Reference von Martens1868), they consist of a chitinous base reinforced with amorphous minerals (mainly calcium carbonate and calcium phosphate) and are covered by a hard, resistant layer of crystalline fluorapatite resembling in appearance and function the enamel of vertebrate teeth (Bentov et al., Reference Bentov, Zaslansky, Al-Sawalmih, Masic, Fratzl, Sagi, Berman and Aichmayer2012). The gross morphology of these teeth, usually named as “molariforms” or “molars,” is diagnostic and may enable isolated pieces to be referred to particular parastacid lineages (Bentov et al., Reference Bentov, Aflalo, Tynyakov, Glazer and Sagi2016; Vojkovská et al., Reference Vojkovská, Horká and Ďuriš2020; Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025). Fossil records of these molariform structures are extremely scarce. The first identification of fossil freshwater crayfish based on fragments of the molar ridge from their mandibles has only recently been reported (Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025).

A recent reorganization of materials housed in the paleontological collections of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (MACN) resulted in finding several isolated parastacid “molars.” Historically, these materials were poorly understood and frequently misinterpreted as vertebrate teeth, which led to their inclusion in the paleovertebrate collection. They had been classified as possible Cretaceous mammalian teeth and, in some cases (such as MACN-Pv RN1152), even identified as a possible batoid fish tooth. These specimens come from Maastrichtian beds at Los Alamitos farm (currently known as Nueva Poupeé farm), Río Negro province, northern Patagonia, Argentina, and were collected during expeditions led by José F. Bonaparte and his team in the 1980s. These constitute the oldest parastacid body fossils from South America. The aim of the present contribution is to describe these specimens and analyze their paleobiogeographical implications.

Materials and methods

Geographic and geologic settings

The Upper Cretaceous Los Alamitos Formation (Maastrichtian; Bonaparte et al., Reference Bonaparte, Franchi, Powell and Sepulveda1984; Andreis, Reference Andreis1987; Franchi et al., Reference Franchi, Ardolino, Remesal, Caba, Dalponte and Lizuaín2001) is a well-known stratigraphic unit primarily because of its abundant vertebrate record, which includes important mammals (Bonaparte et al., Reference Bonaparte, Franchi, Powell and Sepulveda1984; Bonaparte, Reference Bonaparte1986, Reference Bonaparte1994, Reference Bonaparte2002; Albino, Reference Albino1987, Reference Albino2000; Báez, Reference Báez1987; de Broin, Reference de Broin1987; Powell, Reference Powell1987, Reference Powell2003; Apesteguía, Reference Apesteguía2005; Agnolin and Martinelli, Reference Agnolin and Martinelli2009; Gómez, Reference Gómez2016; Rougier et al., Reference Rougier, Martinelli and Forasiepi2021). The formation was initially deposited in a shallow lacustrine environment near the marine coast, with low-lying coastal plains containing freshwater bodies and fluvial channels during deposition of the lower member, whereas the upper member records an increasing marine influence (Franchi et al., Reference Franchi, Ardolino, Remesal, Caba, Dalponte and Lizuaín2001).

The revision of the paleontological collections housed at the MACN led to the discovery of several fragments of parastacid molars among vertebrate specimens collected at the Cerro Cuadrado locality (41°57′13.5″S, 66°19′20.3″W; 582 m above sea level), Nueva Poupée Farm (formerly Los Alamitos Farm), approximately 60 km from Arroyo Ventana locality, Valcheta Department, Río Negro province, Patagonia, Argentina. Some of these specimens were tentatively classified as mammalian teeth. The specimens come from non-calcareous pelitic facies of the lower member of the Los Alamitos Formation (sensu Andreis, Reference Andreis1987).

Nomenclature

We follow the anatomical nomenclature of Vojkovská et al. (Reference Vojkovská, Horká and Ďuriš2020), with the modifications carried out by Worthy et al. (Reference Worthy, Scofield, Worthy, De Pietri and Archer2025). The taxonomy of Astacidea and Parastacidae follows Crandell and de Grave (Reference Crandall and de Grave2017). The anatomy of the molar ridges among freshwater astacideans has been shown to be informative at the suprageneric and specific levels (Hobbs, Reference Hobbs1991; Kawai and Patoka, Reference Kawai and Patoka2020; Vojkovská et al., Reference Vojkovská, Horká and Ďuriš2020; Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025). We follow these authors in presuming that the molars have taxonomic value.

Micro‑CT scanning and processing

The specimen MACN-Pv RN1152 was scanned in a NIKON XT H 225 ST 2× micro-CT system using a tube voltage of 80 kV and a current of 125 μA. Scanning parameters included 720 projections with one frame per projection, a magnification factor of 12.35, a source-to-object distance of 382.23 mm, and a source-to-detector distance of 1,122.48 mm, resulting in a voxel size of 12.14 μm. Virtual three-dimensional reconstructions were obtained and visualized using the Amira 5.3.3 software.

Repository and institutional abbreviation

MACN-Pv, Colección Nacional Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia,” Buenos Aires, Argentina.

Systematic paleontology

Decapoda Latreille, Reference Latreille1802

Astacidea Latreille, Reference Latreille1802

Parastacoidea Huxley, Reference Huxley1879

Parastacidae Huxley, Reference Huxley1879

Parastacidae gen. indet. sp. indet.

Referred material

MACN-Pv RN1152, complete cephalic molar, MACN-Pv RN1153, MACN-Pv RN1154, MACN-Pv RN1155, MACN-Pv RN1156, each corresponding to an incompletely preserved cephalic molar field.

Description

The presence of a raised mineralized structure preserved on a convex outer surface allows identification of the fossils as cephalic molar fields from the internal side of a parastacid mandible (Hobbs, Reference Hobbs1991). In all the specimens to be described, large cusps are observed on the rasping surface, and the lateral side is much higher than the internal side.

MACN-Pv RN1152 (Fig. 1)

This specimen preserves the complete molar cephalic field supported by its mandibular base. This cephalic molar field is represented by a subrectangular structure whose outer surface is continuous but slightly undulated, bearing low notches on the more elevated lateral side, and enclosing an elongate central depression. The outer rim has a much narrower and sharper crest and a sigmoidal contour in occlusal view, whereas the inner rim is lower, with a rounded crest, and nearly straight along its length. The entire outer surface bears small pits and transverse ridges. Three cusps (with fragmented apices) are distributed along the lateral margin: a large anterolateral cusp, a centrolateral cusp larger than the former, and a posterolateral cusp smaller than the previous two. The central depression forms a shallow longitudinal groove. The centrolateral cusp largely divides this central depression into two depressions. The posterolateral corner of the cephalic molar field shows a prominent convex surface. The anterior margin of the field is convex, whereas the posterior one is nearly straight. The more elevated side of the cephalic molar field is that closest to the incisor process of the mandible. The enamel-like surface of apatite of the cephalic molar field is relatively thick and bright. In lateral view, the wall shows a highly sinuous dorsal outline because of the three cusps and the constrictions between them. This outer wall also shows a crenulate ornamentation composed of many fine ridges that are aligned from the crest to the base. The central depression also has crenulate ridges leading from the lateral rim that converge toward the middle of the cephalic molar field.

Figure 1.

Complete parastacid cephalic molar field from Los Alamitos Formation. (left) MACN-Pv RN1152 and (right) microCT-scans in (1) dorsal, (2) lateral, and (3) medial views compared with (4) dorsal (internal) view of right mandible of Astacopsis franklinii (Gray, Reference Gray1845) from Tasmania (Canterbury Museum, Christchurch, New Zealand: CM AQ 1809). The lines drawn on the microCT models indicate the reconstructed original outline of the molar process before erosion. alc, anterolateral cusps; camf, caudal molar field; cemf, cephalic molar field; clc, centrolateral cusp; cd, central depression; lw, lateral wall; mb, mandibular base; mw, medial wall; plc, posterolateral cups. Scale bars = 1 mm.

Content of image described in text.

MACN-Pv RN1153 (Fig. 2.1–2.5)

The posterior half of a cephalic molar field is preserved. On the grinding surface, two large cusps are present along the lateral margin, in the same position as the centrolateral and posterolateral cusps of the previous specimen. The lateral margin between the cusps forms a crest that connects them. The grinding surface differs from that of MACN-Pv RN1152 as it is smoother despite having less wear to the main cusps and bears large denticles separated by grooves on the inner and distal margins (Fig. 2.5).

Figure 2.

Fragments of parastacid cephalic molar field from Los Alamitos Formation. (1–5) MACN-Pv RN1153, posterior half of right cephalic molar field. (6–10) MACN-Pv RN1154, anterior half of right cephalic molar field. (11–15) MACN-Pv RN1155, posterior half of left cephalic molar field. (16–20) Posterior half of left cephalic molar field. (1, 6, 11, 16) Dorsal views; (2, 7, 12, 17) lateral views; (3, 8, 13, 18) medial views; (4, 9, 14, 19) anterior views; (5, 10, 15, 20) posterior views. alc, anterolateral cups; cd, central depression; clc, centrolateral cusp; plc, posterolateral cups. Scale bar = 1 mm.

Content of image described in text.

MACN-Pv RN1154 (Fig. 2.6–2.10)

Part of the anterior half of a cephalic molar field is preserved. This fragment more closely resembles MACN-Pv RN1152 as it presents two cusps—the centrolateral cusp and the anterolateral cusp—separated by several small denticles, unlike MACN-Pv RN1153. However, the anterolateral cusp is not located at the corner of the grinding surface but rather in a subterminal position—a condition that may be accentuated by the limited wear of this specimen as more extensive wear could produce a morphology closer to that seen in MACN-Pv RN1152—and there is no marked central depression. As in the previous specimens, the centrolateral cusp is higher than the posterolateral cusp. The grinding surface is crenulated, with small denticles and without punctuations.

MACN-Pv RN1155 (Fig. 2.11–2.15)

This is the most poorly preserved specimen as it retains only a small portion of the posterior sector of the cephalic molar field. The grinding surface is finely crenulated and bears thin, low ridges without punctuations. On the lateral margin is a pronounced centrolateral cusp, and posteriorly the base of the posterolateral cusp is visible. Between them, the margin shows fine ridges. The posterior end meets the medial margin in the same sharp and wide angle as seen in MACN-Pv RN1152. The posterior and inner margins bear small ridges and tiny denticles.

MACN-Pv RN1156 (Fig. 2.16–2.20)

This specimen preserves the distal end of the posterior sector of a cephalic molar field. It most closely resembles MACN-Pv RN1152 as it shows a crenulated and punctuated grinding surface. On the posterolateral corner is a relatively low and rounded cusp. On the posteromedial corner, a small cusp is formed by a denticle more developed than the others. From this cusp, a ridge without denticles descends toward the base of the central depression.

Remarks

The age and geographical position of the specimens from Los Alamitos, together with their morphological distinctiveness, indicate that they belong to a distinctive, unnamed genus. However, the paucity of the available material precludes a clear taxonomic referral.

Discussion

As occurs with other invertebrates, the systematics of the infraorder Astacidea is based on morphological features usually not preserved in the fossils. For this reason, other attributes should be considered when studying fossils (Aguirre-Urreta, Reference Aguirre-Urreta1992), such as the molar field anatomy, disposition, and ornamentation, which have been considered to be taxonomically informative in freshwater astacideans. For example, Vojkovská et al. (Reference Vojkovská, Horká and Ďuriš2020) reviewed the structure of the molar process in freshwater crayfish (Astacoidea and Parastacoidea) and demonstrated that the parastacids varied greatly from the Northern Hemisphere modern families (Astacidae, Cambaridae, Cambaroididae) by the cephalic molar field (cemf) being very large relative to the molar process and ridged versus much smaller and flat in the other families and by the caudal molar field (camf) being multi-tuberculate rather than having a single or bicuspid tubercle. Therefore, the specimens described here may be confidently referred to Parastacidae because they have a relatively large, elongate, and ridged cephalic molar shield with an enamel-like wear-resistant coating on the outer surface (Bentov et al., Reference Bentov, Zaslansky, Al-Sawalmih, Masic, Fratzl, Sagi, Berman and Aichmayer2012; Vojkovská et al., Reference Vojkovská, Horká and Ďuriš2020; Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025).

When compared with specimens of other parastacids, those from Los Alamitos show a unique combination of traits. First, MACN-Pv RN1152 exhibits a subrectangular outline. This general morphology is also compatible with the other referred specimens: for example, MACN-Pv RN1156 and MACN-Pv RN1155 can be readily mirrored onto the outline of MACN-Pv RN1152, and MACN-Pv RN1154 shows a somewhat more squared crest around the margin that is likewise consistent with a subrectangular form. This is clearly different from the reduced cephalic molar process of the South American parastacids, such as species of Parastacus, Samastacus, and Virilastacus (Hobbs, Reference Hobbs1991). It also distinguishes them from the oval-shaped molars of the extant Australasian species of Euastacus, Cherax, Paranephrops, and Astacopsis as well as the fossil specimens described from the Miocene of New Zealand (Hobbs, Reference Hobbs1987; Kawai and Patoka, Reference Kawai and Patoka2020; Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025). In addition, the specimens from Los Alamitos have sharp cusps adjacent to the lateral rim of the grinding surface. Although Cherax also exhibits prominent posterolateral and centrolateral cusps (e.g., Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025, fig. 2A), the New Zealand fossils lack such differentiated lateral cusps and show a more uniformly elevated surface. The remains described here also differ from the cephalic molar field species of Paranephrops because they show a longitudinal depression and a ridged surface versus flattened and cellular surface texture (Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025). In other parastacids, such as species of Cherax and Astacoides caldwelli (Spence Bate in Sclater, Reference Sclater1865), the cephalic molar field bears large transverse ridges with rounded pits between them. Although Cherax shares with the Patagonian specimens the presence of a central depression, crenulated ridges extending from the rim toward the center, and lateral cusps, its overall ridge–pit morphology remains distinct. In Astacoides, the ridges arise only from the medial side, where the surface exhibits a cellular texture, further differing from the Patagonian material (Bentov et al., Reference Bentov, Aflalo, Tynyakov, Glazer and Sagi2016; Kawai and Patoka, Reference Kawai and Patoka2020; Vojkovská et al., Reference Vojkovská, Horká and Ďuriš2020). Posterior to the cephalic molar field is a large space at the mandibular base indicating that the caudal fields and other adjacent structures were well separated. This feature is shared with the Madagascan species of Astacoides and differs from species of Virilastacus, Parastacus, Astacopsis, Samastacus, Euastacus, and Cherax (Hobbs, Reference Hobbs1987, Reference Hobbs1991; Kawai and Patoka, Reference Kawai and Patoka2020; Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025). However, the truncated shape of the caudal end, with the caudal sector wider transversely than the anterior sector, a sigmoidal lateral margin, and a straight inner margin, as seen in MACN-Pv RN1152 and MACN-Pv RN1153, is also observed in some extant parastacids, such as Cherax monticola. Although in this species the caudal molar field and the adjacent structures are almost in contact with the cephalic field (Kawai and Patoka, Reference Kawai and Patoka2020), this condition differs from that observed in the specimens described here.

Judging from these comparisons, it is possible that the Los Alamitos crayfish was perhaps most closely related to Malagasy taxa.

Although the materials described here exhibit some morphological variation, it is plausible that three of the specimens correspond to the same species and that the remaining one differs only slightly. However, such variation could also reflect differences in the ontogenetic stages or other natural processes (Loya-Javellana and Fielder, Reference Loya-Javellana and Fielder1997; Tynyakov et al., Reference Tynyakov, Bentov, Abehsera, Khalaila, Manor, Katzir Abilevich, Weil, Aflalo and Sagi2015).

Paleobiogeography

Parastacoidea includes 15 genera of extant species, of which 11 are found in Australasia, three in South America, and one in Madagascar (Crandall and Buhay, Reference Crandall and Buhay2008). They have not been found in continental Africa, the Indian subcontinent, or Antarctica, probably because they appear to need temperate waters and cannot tolerate a harsh climate (Martin et al., Reference Martin, Rich, Poore, Schultz, Austin, Kool and Vickers-Rich2008; Bell et al., Reference Bell, Bicknell and Smith2020; Audo et al., Reference Audo, Hasiotis and Kawai2023). Parastacid species richness and biogeographical history of many of these genera appear to be the result of vicariance and dispersal associated with isolation events (e.g., Ponniah and Hughes, Reference Ponniah and Hughes2004; Shull et al., Reference Shull, Pérez-Losada, Blair, Sewell, Sinclair, Lawler, Ponniah and Crandall2005; Crandal and Buhay, Reference Crandall and Buhay2008).

Mesozoic parastacoid records are problematic. The oldest parastacoid occurrence in Gondwana is based on burrows from the Upper Jurassic of Argentina (Bedatou et al., Reference Bedatou, Melchor, Bellosi and Genise2008). Diverse Early and Late Cretaceous crayfish burrows have also been reported from Argentina (Bedatou et al., Reference Bedatou, Melchor, Bellosi and Genise2008; Genise et al., Reference Genise, Bedatou and Melchor2008) and Australia (Tucker and Tucker, Reference Tucker and Tucker2019), but because they do not contain unambiguous crayfish attributes, they have been questioned by some authors (Hanneman et al., Reference Hanneman, Lofgren, Hasiotis and Mcintosh2022; Audo et al., Reference Audo, Hasiotis and Kawai2023). Early Cretaceous opalized biogastroliths from Australia and Late Cretaceous biogastroliths from several localities in Patagonia, Argentina, were considered as evidence for the occurrence of crayfishes, and the fossils from Australia were regarded to be parastacids (Bell et al., Reference Bell, Bicknell and Smith2020; Audo et al., Reference Audo, Hasiotis and Kawai2023; Panzeri et al., Reference Panzeri, Bogan, Raigemborn, Pagani, Chimento, Agnolín and Martinelli2024). As indicated, burrows and biogastroliths can be only tentatively referred to Parastacidae rather than to Astacidae. Such assessments, when they have been made, have been based primarily on modern biogeography (Bell et al., Reference Bell, Bicknell and Smith2020).

The widespread presence of Early Cretaceous crayfishes in the Southern Hemisphere is supported by the finding of three Albian body fossils of Palaeoechinastacus australianus Martin et al., Reference Martin, Rich, Poore, Schultz, Austin, Kool and Vickers-Rich2008 (Martin et al., Reference Martin, Rich, Poore, Schultz, Austin, Kool and Vickers-Rich2008; Bell et al., Reference Bell, Bicknell and Smith2020). Cenozoic body fossils are known from the Oligocene–Miocene of Chile and Argentina (Cisternas and Díaz, Reference Cisternas and Diaz1986; Aguirre-Urreta, Reference Aguirre-Urreta1992), the Miocene of New Zealand (Feldmann and Pole, Reference Feldmann and Pole1994; Worthy et al., Reference Worthy, Scofield, Worthy, De Pietri and Archer2025), and the Paleogene and Miocene of Australia (Sokol, Reference Sokol1987). A possible parastacid from Canada (Wehr and Barksdale, Reference Wehr and Barksdale1995; Feldmann et al., Reference Feldmann, Schweitzer and Leahy2011) represents the only occurrence outside the Southern Hemisphere (Audo et al., Reference Audo, Hasiotis and Kawai2023). This report constitutes the oldest certain record of parastacoids in South America and the second Cretaceous record for the Southern Hemisphere.

Ortmann (Reference Ortmann1902) suggested that a Mesozoic biotic pathway must have connected Australia and New Zealand with South America. The existence of such a dispersal route for decapod crustaceans has received some support (Feldmann, Reference Feldmann1984; Feldmann and Zinsmeister, Reference Feldmann and Zinsmeister1984; Feldmann and McLay, Reference Feldmann and McLay1993). In this regard, the presence of a Late Cretaceous parastacid in Patagonia reinforces the idea that the clade was widespread across southern Gondwana (e.g., Patagonia, Australia, New Zealand) during the Mesozoic, and it seems probable that fossil remains of this clade will also be found in Antarctica. These findings fit well with the hypothesis of an early high-latitude radiation of the clade followed by later dispersal, as previously proposed for dispersals of both parastacids and aeglids (Feldmann, Reference Feldmann1984; Feldmann and Pole, Reference Feldmann and Pole1994). They also lend support to hypotheses previously suggested in relation to broader biogeographic patterns (Feldmann and Zinsmeister, Reference Feldmann and Zinsmeister1984; Feldmann and McLay, Reference Feldmann and McLay1993; Feldmann and Pole, Reference Feldmann and Pole1994).

The discoveries reported here fill an important temporal gap between the Early Cretaceous fossils from Australia and those of the Paleogene of South America and Australia. They also lend indirect support to the parastacid affinities suggested for Cretaceous biogastroliths from Patagonia and Australia (Panzeri et al., Reference Panzeri, Bogan, Raigemborn, Pagani, Chimento, Agnolín and Martinelli2024).

Acknowledgments

We express our gratitude to A. Moreno Rodríguez for her assistance in handling and preparing the material and to other members of LACEV (Laboratorio de Anatomía Comparada y Evolución de los Vertebrados) and Sección Paleontología de Vertebrados for their comments and assistance in curatorial tasks. This contribution was made possible thanks to funding provided by the Mamont Scholar Grant 2020 program of The Explorers Club to N.C. and National Geographic Society Grant (NGS-92822R-22) “The end of the dinosaur era in Patagonia” to D. Pol. We are grateful to the reviewers, D. Audo and C.E. Schweitzer, for their constructive comments and suggestions, which helped improve the manuscript, and to the editors, O. Vinn and J. Kastigar, for their careful handling of the manuscript.

Competing interests

The authors declare none.

Footnotes

Handling Editor: Olev Vinn

References

Agnolin, F.L., and Martinelli, A.G., 2009, Fossil birds from the Late Cretaceous Los Alamitos Formation, Río Negro province, Patagonia: Journal of South American Earth Sciences, v. 27, p. 42–49.10.1016/j.jsames.2008.09.003CrossRefGoogle Scholar
Aguirre-Urreta, M.B., 1992, Tertiary freshwater Decapoda (Crustacea: Parastacidae) from the Ñirihuau Basin, Patagonia, Argentina: Journal of Paleontology, v. 66, p. 817–825.10.1017/S0022336000020825CrossRefGoogle Scholar
Albino, A., 1987, The Late Cretaceous fauna of Los Alamitos, Patagonia, Argentina. Part V - ophidians, in Bonaparte, J.F., coord., The Late Cretaceous Fauna of Los Alamitos, Patagonia, Argentina: Revista del Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Paleontología, v. 3, p. 141–146.Google Scholar
Albino, A., 2000, New record of snakes from the Cretaceous of Patagonia (Argentina): Geodiversitas, v. 22, p. 247–253.Google Scholar
Andreis, R.R., 1987, The Late Cretaceous fauna of Los Alamitos, Patagonia, Argentina. Part I - stratigraphy and paleoenvironment, in Bonaparte, J.F., coord., The Late Cretaceous Fauna of Los Alamitos, Patagonia, Argentina: Revista del Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Paleontología, v. 3, p. 103–110.Google Scholar
Apesteguía, S., 2005, A late Campanian sphenodontid (Reptilia, Diapsida) from northern Patagonia: Comptes Rendus Palevol, v. 4, p. 663–669.10.1016/j.crpv.2005.06.003CrossRefGoogle Scholar
Audo, D., Hasiotis, S.T., and Kawai, T., 2023, Diversity and evolutionary history of fossil crayfishes: Journal of Crustacean Biology, v. 43, n. ruad079.10.1093/jcbiol/ruad079CrossRefGoogle Scholar
Báez, A.M., 1987, The Late Cretaceous fauna of Los Alamitos, Patagonia, Argentina. Part III - anurans, in Bonaparte, J.F., coord., The Late Cretaceous Fauna of Los Alamitos, Patagonia, Argentina: Revista del Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Paleontología, v. 3, p. 121–130.Google Scholar
Bell, P.R., Bicknell, R.D., and Smith, E.T., 2020, Crayfish biogastroliths from eastern Australia and the middle Cretaceous distribution of Parastacidae: Geological Magazine, v. 157, p. 1023–1030.10.1017/S0016756819001092CrossRefGoogle Scholar
Bedatou, E., Melchor, R.N., Bellosi, E., and Genise, J.F., 2008, Crayfish burrows from Late Jurassic–Late Cretaceous continental deposits of Patagonia: Argentina. Their palaeoecological, palaeoclimatic and palaeobiogeographical significance: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 257, p. 169–184.10.1016/j.palaeo.2007.09.020CrossRefGoogle Scholar
Bentov, S., Zaslansky, P., Al-Sawalmih, A., Masic, A., Fratzl, P., Sagi, A., Berman, A., and Aichmayer, B., 2012, Enamel-like apatite crown covering amorphous mineral in a crayfish mandible: Nature Communications, v. 3, n. 839.10.1038/ncomms1839CrossRefGoogle Scholar
Bentov, S., Aflalo, E. D., Tynyakov, J., Glazer, L., and Sagi, A., 2016, Calcium phosphate mineralization is widely applied in crustacean mandibles: Scientific Reports, v. 6, n. 22118.10.1038/srep22118CrossRefGoogle ScholarPubMed
Bonaparte, J.F., 1986, A new and unusual Late Cretaceous mammal from Patagonia: Journal of Vertebrate Paleontology, v. 6, p. 264–270.10.1080/02724634.1986.10011621CrossRefGoogle Scholar
Bonaparte, J.F., 1994, Approach to the significance of the Late Cretaceous mammals of South America: Berliner Geowissenschaften Abhandlugen, v. 13, p. 31–44.Google Scholar
Bonaparte, J.F., 2002, New Dryolestida (Theria) from the Late Cretaceous of Los Alamitos Formation, Argentina, and paleogeographical comments: Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, v. 224, p. 339–371.10.1127/njgpa/224/2002/339CrossRefGoogle Scholar
Bonaparte, J.F., Franchi, M.R., Powell, J.E., and Sepulveda, E.G., 1984, La Formación Los Alamitos (Campaniano-Maastrichtiano) del sudeste de Río Negro, con descripción de Kritosaurus australis n. sp. (Hadrosauridae). Significado paleogeográfico de los vertebrados: Revista de la Asociación Geológica Argentina, v. 39, p. 284–299.Google Scholar
Bracken-Grissom, H.D., Ahyong, S.T., Wilkinson, R.D., Feldmann, R.M., Schweitzer, C.E., et al., 2014, The emergence of lobsters: phylogenetic relationships, morphological evolution and divergence time comparisons of an ancient group (Decapoda: Achelata, Astacidea, Glypheidea, Polychelida): Systematic Biology, v. 63, p. 457–479.10.1093/sysbio/syu008CrossRefGoogle ScholarPubMed
Cisternas, M.E., and Diaz, L.L., 1986, Los depósitos terciarios lacustres de Lonquimay, Chile: Zentralblatt für Geologie und Palaontologie, Teil I, v. 9/10, p. 1351–1362.10.1127/zbl_geol_pal_1/1985/1986/1351CrossRefGoogle Scholar
Crandall, K.A., and Buhay, J.E., 2008, Global diversity of crayfish (Astacidae, Cambaridae, and Parastacidae––Decapoda) in freshwater: Hydrobiologia, v. 595, p. 295–301.10.1007/s10750-007-9120-3CrossRefGoogle Scholar
Crandall, K.A., and de Grave, S., 2017, An updated classification of the freshwater crayfishes (Decapoda: Astacidea) of the world, with a complete species list: Journal of Crustacean Biology, v. 37, p. 615–653.10.1093/jcbiol/rux070CrossRefGoogle Scholar
de Broin, F., 1987, The Late Cretaceous fauna of Los Alamitos, Patagonia, Argentina. Part 4 - Chelonia, in Bonaparte, J.F., coord., The Late Cretaceous Fauna of Los Alamitos, Patagonia, Argentina: Revista del Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Paleontología, v. 3, p. 131–178.Google Scholar
Feldmann, R.M., 1984, Haumuriaegla glaessneri n. gen. and sp. (Decapoda; Anomura; Aeglidae) from Haumurian (Late Cretaceous) rocks near Cheviot, New Zealand: New Zealand Journal of Geology and Geophysics, v. 27, p. 379–385.Google Scholar
Feldmann, R.M., and McLay, C.L., 1993, Geological history of brachyuran decapods from New Zealand: Journal of Crustacean Biology, v. 13, p. 443–455.10.2307/1548787CrossRefGoogle Scholar
Feldmann, R.M., and Pole, M., 1994, A new species of Paranephrops White, 1842: a fossil freshwater crayfish (Decapoda: Parastacidae) from the Manuherikia group (Miocene), central Otago, New Zealand: New Zealand Journal of Geology and Geophysics, v. 37, p. 163–167.10.1080/00288306.1994.9514611CrossRefGoogle Scholar
Feldmann, R.M., and Zinsmeister, W.J., 1984, New fossil crabs (Decapoda: Brachyura) from the La Meseta Formation (Eocene) of Antarctica: paleogeographic and biogeographic implications: Journal of Paleontology, v. 58, p. 1046–1061.Google Scholar
Feldmann, R.M., Schweitzer, C.E., and Leahy, J., 2011, New Eocene crayfish from the McAbee beds in British Columbia: first record of Parastacoidea in the Northern Hemisphere: Journal of Crustacean Biology, v. 31, p. 320–331.10.1651/10-3399.1CrossRefGoogle Scholar
Franchi, M., Ardolino, A.A., Remesal, M., Caba, R., Dalponte, M.R., and Lizuaín, A., 2001, Hoja Geológica 4166-III Cona Niyeu. Programa Nacional de Cartas Geológicas de la República Argentina. SEGEMAR, Boletín del Servicio Geológico Minero Argentino, v. 262, 82 p.Google Scholar
Genise, J.F., Bedatou, E., and Melchor, R.N., 2008, Terrestrial crustacean breeding trace fossils from the Cretaceous of Patagonia (Argentina): palaeobiological and evolutionary significance: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 264, p. 128–139.10.1016/j.palaeo.2008.04.004CrossRefGoogle Scholar
Gómez, R.O., 2016, A new pipid frog from the Upper Cretaceous of Patagonia and early evolution of crown-group Pipidae: Cretaceous Research, v. 62, p. 52–64.10.1016/j.cretres.2016.02.006CrossRefGoogle Scholar
Gray, J., 1845, Appendix, description of some new Australian animals, in Eyre, E., Journals of Expeditions of Discovery into Central Australia and Overland from Adelaide to King George Sound, in the years 1840–41, Volume I: London, T. and W. Boone.Google Scholar
Hanneman, D.L., Lofgren, D., Hasiotis, S.T., and Mcintosh, W.C., 2022, Priabonian, late Eocene chronostratigraphy, depositional environment, and paleosol-trace fossil associations, Pipestone Springs, southwest Montana: Acta Palaeontologica Polonica, v. 67, p. 5–20.10.4202/app.00901.2021CrossRefGoogle Scholar
Hasiotis, S.T., 2002, Where is the fossil evidence for Gondwanan crayfish?: Gondwana Research, v. 5, p. 872–878.10.1016/S1342-937X(05)70921-7CrossRefGoogle Scholar
Hobbs, H.H., 1987, A review of the crayfish genus Astacoides (Decapoda: Parastacidae): Smithsonian Contributions to Zoology, v. 443, p. 1–50.10.5479/si.00810282.443CrossRefGoogle Scholar
Hobbs, H.H., 1991, A new generic assignment for a South American crayfish (Decapoda: Parastacidae) with revised diagnoses of the South American genera and comments on the parastacid mandible: Proceedings of the Biological Society of Washington, v. 104, p. 800–811.Google Scholar
Huxley, T.H., 1879, On the classification and the distribution of the crayfishes: Proceedings of the Zoological Society of London 1878, Part IV, v. 49, p. 752–788.Google Scholar
Kawai, T., and Patoka, J., 2020, Morphology of gastric mills and mandibles of New Guinean parastacid crayfishes, with comparisons with other Astacidea (Decapoda): Journal of Crustacean Biology, v. 40, p. 692–703.10.1093/jcbiol/ruaa081CrossRefGoogle Scholar
Latreille, P.A., 1802, Histoire Naturelle, Générale et Particulière des Crustacés et Insectes. Familles Naturelles des Genres, Tome Troisième: Paris, F. Dufart, 467 p.10.5962/bhl.title.15764CrossRefGoogle Scholar
Loya-Javellana, G.N., and Fielder, D.R., 1997, Developmental trends in the mouthparts during growth from juvenile to adult of the tropical freshwater crayfish, Cherax quadricarinatus von Martens, 1868 (Decapoda: Parastacidae): Invertebrate Reproduction & Development, v. 32, p. 167–175.10.1080/07924259.1997.9672619CrossRefGoogle Scholar
Martin, A.J., Rich, T.H., Poore, G.C., Schultz, M.B., Austin, C.M., Kool, L., and Vickers-Rich, P., 2008, Fossil evidence in Australia for oldest known freshwater crayfish of Gondwana: Gondwana Research, v. 14, p. 287–296.10.1016/j.gr.2008.01.002CrossRefGoogle Scholar
Ortmann, A.E., 1902, The geographical distribution of freshwater decapod and its bearing upon ancient geography: Proceedings of the American Philosophical Society, v. 41, p. 267–400.Google Scholar
Panzeri, K.M., Bogan, S., Raigemborn, M.S., Pagani, M.A., Chimento, N., Agnolín, F.L., and Martinelli, A.G., 2024, Purported crushing teeth of actinopterygian fishes from the Late Cretaceous of Patagonia reinterpreted as crustacean bio-gastroliths: Journal of South American Earth Sciences, v. 149, n. 105179.10.1016/j.jsames.2024.105179CrossRefGoogle Scholar
Ponniah, M., and Hughes, J., 2004, The evolution of Queensland spiny mountain crayfish of the genus Euastacus: I. Testing vicariance and dispersal with interspecific mtDNA: Evolution, v. 58, p. 1073–1085.10.1111/j.0014-3820.2004.tb00441.xCrossRefGoogle Scholar
Powell, J.E., 1987, The Late Cretaceous fauna of Los Alamitos, Patagonia, Argentina. Part VI - the titanosaurids, in Bonaparte, J.F., coord., The Late Cretaceous Fauna of Los Alamitos, Patagonia, Argentina: Revista del Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Paleontología, v. 3, p. 147–153.Google Scholar
Powell, J.E., 2003, Revision of South American titanosaurid dinosaurs: palaeobiological, palaeobiogeographical and phylogenetic aspects: Records of the Queen Victoria Museum, v. 111, p. 1–173.Google Scholar
Rougier, G.W., Martinelli, A.G., and Forasiepi, A.M., 2021, Mesozoic Mammals from South America and their Forerunners: Cham, Switzerland, Springer, 388 p.10.1007/978-3-030-63862-7CrossRefGoogle Scholar
Sclater, P.L., 1865, Report on a collection of animals from Madagascar, transmitted to the Society by Mr. J. Caldwell: Proceedings of the Zoological Society of London, v. 1865, p. 467–470, pl. 27.Google Scholar
Shull, H.C., Pérez-Losada, M., Blair, D., Sewell, K., Sinclair, E.A., Lawler, S., Ponniah, M., and Crandall, K.A., 2005, Phylogeny and biogeography of the freshwater crayfish Euastacus (Decapoda: Parastacidae) based on nuclear and mitochondrial DNA: Molecular Phylogenetics and Evolution, v. 37, p. 249–263.10.1016/j.ympev.2005.04.034CrossRefGoogle ScholarPubMed
Sokol, A., 1987, A note on the existence of pre-Pleistocene fossils of parastacid crayfish: Victorian Naturalist, v. 104, p. 81–82.Google Scholar
Toon, A., Pérez‐Losada, M., Schweitzer, C.E., Feldmann, R.M., Carlson, M., and Crandall, K.A., 2010, Gondwanan radiation of the Southern Hemisphere crayfishes (Decapoda: Parastacidae): evidence from fossils and molecules: Journal of Biogeography, v. 37, p. 2275–2290.10.1111/j.1365-2699.2010.02374.xCrossRefGoogle Scholar
Tucker, E.A., and Tucker, M.E., 2019, Crayfish gastroliths: Geology Today, v. 35, p. 26–28.10.1111/gto.12254CrossRefGoogle Scholar
Tynyakov, J., Bentov, S., Abehsera, S., Khalaila, I., Manor, R., Katzir Abilevich, L., Weil, S., Aflalo, E.D., and Sagi, A., 2015, A novel chitin binding crayfish molar tooth protein with elasticity properties. PLoS One, v. 10, n. e0127871.10.1371/journal.pone.0127871CrossRefGoogle ScholarPubMed
Vojkovská, R., Horká, I., and Ďuriš, Z., 2020, Comparative morphology of crayfish mandibles, with insight into their evolution: Journal of Morphology, v. 281, p. 365–376.10.1002/jmor.21104CrossRefGoogle ScholarPubMed
von Martens, E., 1868, Über einige neue Crustaceen: Monatsberichte der Königlichen Preussische Akademie der Wissenschaften zu Berlin, v. 1868, p. 607–619.Google Scholar
Wehr, W.C., and Barksdale, L.L., 1995, Implication of middle Eocene feathers and crayfish from crayfish from Republic, Washington: Washington Geology, v. 23, p. 6–10.Google Scholar
Wolfe, J.M., Breinholt, J.W., Crandall, K.A., Lemmon, A.R., Lemmon, E.M., Timm, L.E., Siddall, M.E., and Bracken-Grissom, H.D., 2019, A phylogenomic framework, evolutionary timeline and genomic resources for comparative studies of decapod crustaceans: Proceedings of the Royal Society B: Biological Sciences, v. 286, n. 20190079.10.1098/rspb.2019.0079CrossRefGoogle ScholarPubMed
Worthy, T.H., Scofield, R.P., Worthy, J.P., De Pietri, V.L., and Archer, M., 2025, Parastacid (Decapoda, Parastacidae) fossil mandible remains from the Early Miocene, New Zealand: Alcheringa, v. 49, p. 649–656.10.1080/03115518.2025.2488056CrossRefGoogle Scholar
Figure 0

Figure 1. Complete parastacid cephalic molar field from Los Alamitos Formation. (left) MACN-Pv RN1152 and (right) microCT-scans in (1) dorsal, (2) lateral, and (3) medial views compared with (4) dorsal (internal) view of right mandible of Astacopsis franklinii (Gray, 1845) from Tasmania (Canterbury Museum, Christchurch, New Zealand: CM AQ 1809). The lines drawn on the microCT models indicate the reconstructed original outline of the molar process before erosion. alc, anterolateral cusps; camf, caudal molar field; cemf, cephalic molar field; clc, centrolateral cusp; cd, central depression; lw, lateral wall; mb, mandibular base; mw, medial wall; plc, posterolateral cups. Scale bars = 1 mm.

Figure 1

Figure 2. Fragments of parastacid cephalic molar field from Los Alamitos Formation. (1–5) MACN-Pv RN1153, posterior half of right cephalic molar field. (6–10) MACN-Pv RN1154, anterior half of right cephalic molar field. (11–15) MACN-Pv RN1155, posterior half of left cephalic molar field. (16–20) Posterior half of left cephalic molar field. (1, 6, 11, 16) Dorsal views; (2, 7, 12, 17) lateral views; (3, 8, 13, 18) medial views; (4, 9, 14, 19) anterior views; (5,10, 15,20) posterior views. alc, anterolateral cups; cd, central depression; clc, centrolateral cusp; plc, posterolateral cups. Scale bar = 1 mm.