Cretaceous Research 35 (2012) 124e132
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Marine reptiles from Late Cretaceous (early Maastrichtian) deposits in Algarrobo, central Chile Rodrigo A. Otero a, *, James F. Parham b, c, Sergio Soto-Acuña d, Paulina Jimenez-Huidobro e, David Rubilar-Rogers f Consejo de Monumentos Nacionales, Av. Vicuña Mackenna n 084, Providencia, Santiago, Chile Alabama Museum of Natural History, 427 6th Ave, Smith Hall, University of Alabama, Box 870340, Tuscaloosa, AL 35487-0340, USA c Department of Biology, California State University, 9001 Stockdale Highway, Bakersfield, CA 93311-1099, USA d Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Universidad de Chile, Las Palmeras 3425, Santiago, Chile e Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada f Área Paleontología, Museo Nacional de Historia Natural, Casilla 787, Santiago, Chile a
b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 13 June 2011 Accepted in revised form 4 December 2011 Available online 9 December 2011
We report new specimens of Late Cretaceous (early Maastrichtian) reptiles collected from Algarrobo, central Chile. The Algarrobo fossils include the northernmost occurrence of marine turtles, articulated plesiosaur remains, and mosasaur teeth recognized in the Weddellian Biogeographic Province. The presence of articulated material and teeth of elasmosaurid plesiosaurs, mosasaur teeth, and postcranial remains of cf. dermochelyid sea turtles re-emphasizes an emerging picture of the composition of Maastrichtian marine reptiles in the Pacific Basin. The fossil reptiles suggest that the Algarrobo strata were deposited on a shallow marine shelf. Proximity to the coast is indirectly suggested by the presence of fossil wood. Ó 2011 Elsevier Ltd. All rights reserved.
Keywords: Marine turtles Plesiosaurs Mosasaurs Early Maastrichtian Central Chile
1. Introduction Fossil reptiles in Late Cretaceous deposits of central Chile were first reported in the 19th century. Most frequently found fossils are plesiosaurs (Gasparini and Goñi, 1985; Gasparini, 2007) followed by mosasaurs (Suárez, 1999; Suárez et al., 2003; Suárez and Otero, 2009) and then turtles (Gasparini and Biró-Bagoczky, 1986; Suárez et al., 2003; Suárez and Otero, 2009). Late Cretaceous reptiles from southernmost Chile are known from three sites near Puerto Natales, belonging to the Dorotea Formation (Katz, 1963) of late Maastrichtian age, where indeterminate plesiosaurs (Cecioni, 1955; Gasparini, 1979), as well as elasmosaurid plesiosaurs were recovered (Otero et al., 2009; Otero and Rubilar-Rogers, 2010). Other Maastrichtian indeterminate plesiosaurs were reported from Lago Parrillar (Gasparini, 1979), which to date is the southernmost record of plesiosaurs in South America. Late Cretaceous reptiles from central Chile are known exclusively from four geological units in the center of the country (Fig. 1A). (1) The Quiriquina Formation (Biró-Bagóczky, 1982), best
* Corresponding author. E-mail address:
[email protected] (R.A. Otero). 0195-6671/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.cretres.2011.12.003
exposed on the island of that name, and Cocholgüe, about 400 km south from Santiago. The Quriquina Formation consists of a basal conglomerate, overlain by cross-bedded yellow sandstones with conglomerate lenses, coquina horizons and green sandstones at the top that include concretionary nodules. It is considered to be late Maastrichtian based on biostratigraphic correlations and several invertebrate taxa (ammonoids and bivalves) with good chronostratigraphic value (Stinnesbeck, 1986, 1996). (2) The Chanco Formation, with its type locality in Chanco, 300 km south from Santiago (Cecioni, 1983). This formation was originally assigned to the late Campanian based on stratigraphic correlations and fossil invertebrates, but currently it is considered to be equivalent to the Quiriquina Formation owing to its similar lithology and fossil fauna; it is, therefore, tentatively assigned to the Maastrichtian (Tavera, 1988; Suárez and Otero, 2009). (3) The Punta Topocalma Formation (Cecioni, 1980). This is a discrete outcrop of marine sediments comprising sandstones and conglomerates of Late Cretaceous age, located 140 km southwest of Santiago, where the presence of indeterminate plesiosaurs was noted by Suárez et al. (2003). (4) The Estratos de la Quebrada Municipalidad (‘Municipalidad Ravine strata’; Gana et al., 1996; EQM hereafter) in Algarrobo, 100 km west from Santiago. The EQM are considered to be early Maastrichtian in age based on fossil invertebrates (Levi de Valenzuela and Aguirre,
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Fig. 1. A, map indicating the location of Algarrobo (33 220 S; 71400 W) and all the localities mentioned in the text with similar Late Cretaceous outcrops in central Chile, being marked with a black square. B, schematic drawing of the geologic setting at Algarrobo.
1966; Tavera, 1980; Stinnesbeck, 1986) and radioisotopic dating (Suárez and Marquardt, 2003). This paper reports the discovery of a relatively rich reptile fauna recovered from the EQM. The Algarrobo specimens include the most complete articulated vertebral sequence of a plesiosaur from this unit, recovered by L. Landbeck in 1862. Additional material from Algarrobo has been recovered during fieldwork since 2006, and includes associated remains of marine turtles, plesiosaurs and mosasaur teeth. These specimens permit a more-detailed comparison with other Maastrichtian reptile faunas from the Pacific Basin (Gasparini et al., 2003; Hiller et al., 2005; Martin et al., 2007) and especially the Weddellian Biogeographic Province (Zinsmeister, 1979) than has been possible hitherto. The Weddellian Biogeographic Province extends from northern Antarctica via New Zealand to southern South America, and is characterized by having plants and animals with ecological affinities in common, mostly developed from the Late Cretaceous until the Late Eocene (Zinsmeister, 1982). Institutional abbreviations. MPC, Museo Paleontológico de Caldera, Atacama; Q, Museo Geológico Lajós Biró, Concepción; SGO.PV, Museo Nacional de Historia Natural, Santiago. All are in Chile.
provided descriptions that lack detail and contain erroneous and/or obsolete identifications of several vertebrates. More recent studies have provided updated identifications, although most of these belong to fossil fishes, identifying the presence of aspidorhynchids (Brito and Suárez, 2003), elasmobranchs (Philippi, 1887; Suárez et al., 2003; Suárez and Cappetta, 2004) and fragmentary remains of marine plesiosaurs and turtles (Suárez et al., 2003). All of these authors considered the outcrops of Algarrobo as directly correlated with the Quiriquina Formation; nevertheless, the considerable distance between Quiriquina and Algarrobo, and the differences in lithology, tectonic setting and age, justified the proposal of Gana et al. (1996) of regard it as a different unit. The EQM is considered to be Maastrichtian in age based on bivalves such as C. acuticostatum and P. hanetiana (Pérez-D’Angelo and Reyes, 1978). Recently this determination has been constrained by a radiometric date on 90Sr/89Sr obtained from bivalve shells (Suárez and Marquardt, 2003) that indicated an age of 69 01 Ma (early Maastrichtian). The vertebrate assemblage reported herein was collected from the lower levels of the section that are exposed during low tides. 3. Systematic paleontology
2. Locality and geologic setting The vertebrate specimens described here were collected from the coastal town of Algarrobo (33 220 S, 71400 W) in Central Chile,100 km west of Santiago (Fig. 1B). The outcrops rest mainly on intrusive rocks assigned to the Mirasol Unit and constrained to the CarboniferousePermian through several UePb radiometric ages (Gana and Tosdal, 1996). This igneous bedrock is unconformably overlain by a discrete sequence of sedimentary rocks exposed along the coast, which include the Late Cretaceous EQM and the Middle Eocene Estratos Algarrobo (Brüggen, 1915; Tavera, 1980; Gana et al., 1996). The EQM comprises discrete transgressive marine beds that extend about 60 m along the coast, and taking into account the angle of dip, have an estimated thickness of 35 m. The EQM are mainly composed of glauconitic sandstones containing vertebrates and invertebrates, and fine conglomerate lenses (Fig. 2). Invertebrates are abundant, particularly the bivalves Cardium (Bucardium) acuticostatum (d’Orbigny, 1842), Pacitrigonia hanetiana (d’Orbigny, 1842) and Buchotrigonia topocalmensis Pérez-D’Angelo and Reyes (1980) (Philippi, 1887; Brüggen, 1915; Tavera, 1980), and carbonized wood remains are common. The authors cited, however,
Reptilia Laurenti, 1768 Testudines Batsch, 1788 (Sensu Joyce et al., 2004) Testudines indet. Fig. 3AeD Material. MPC.11003, neural plate (Fig. 3A, B); MPC.11002, peripheral plate (Fig. 3C, D). Description. The neural plate (MPC.11003, Fig. 3A, B) is subrectangular with small facets in each corner, and the contour of its posterior end is curved. The external surface is smooth and slightly convex whereas the ventral surface has a pronounced keel for articulation with the thoracic vertebrae. The peripheral plate (MPC.11002, Fig. 3C, D) is square with a broad, shallow, transverse groove on its dorsal surface. The medial end is very thin, but the element thickens laterally. Remark. These specimens cannot be identified beyond the level of Testudines.
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Chelonioidea Baur, 1893 Chelonioidea indet. Fig. 3EeG Material. MPC.11001, proximal portion of left humerus. Description. The proximal portion of MPC.11001 is much damaged; nevertheless, it preserves the articular head, and the lateral and medial processes. The lateral process is strongly shifted in distally. The distal portion of the preserved bone displays an oval crosssection, denoting a slender shaft. Remarks. This partial humerus clearly belongs to a marine turtle because, in contrast to the humeri of non-marine turtles, the lateral process is shifted distally and the medial process would have extended proximally past the caput (Hirayama, 1994). Dermochelyidae de Blainville, 1816 cf. Dermochleyidae indet. Fig. 3HeP Material. SGO.PV.6573, associated remains including incomplete left scapula (Fig. 3HeK), right ilium (Fig. 3LeN) and right pubis (Fig. 3O, P). Description. The scapula preserves the acromion process and the glenoid, whereas most of the distal process is lost. The angle between the scapular and the acromion process is about 105 , but this must be considered a rough estimate given that the dorsal scapular process is incomplete. The acromion process displays a tuberosity extended longitudinally and partially diagonally over the shaft. In crosssection, the shape of the acromion is a compressed oval near the glenoid, but it becomes more subcircular distally. The ilium preserves the articular facets for the ischium and pubis, and also the acetabular surface. It has a relatively elongate neck. The pubis lacks the acetabulum, but preserves part of the lateral (pectineal) process that extends anteriorly. The medial portion has a straight symphysis that would have articulated with the left pubis. Remarks. SGO.PV.6573 is tentatively identified as cf. Dermochelyidae based the acromion tubercle. Lehman and Tomlinson (2004) raised some valid questions about whether this character should be used to diagnose dermochelyids, as suggested by Parham and Stidham (1999). They pointed out that Terlinguachelys fishbecki, a specialized marine turtle from the Upper Cretaceous of the USA, shows this feature, but otherwise shares many other characters with protostegids. In any case, the phylogenetic position of T. fishbecki is unresolved and it too may eventually be assigned to Dermochelyidae pending much needed revisions to Cretaceous marine turtle phylogeny. Other parts of SGO.PV.6573 do not help confirm or deny an assignment to Dermochelyidae. The iliac blade is not extended or curved as it is in the dermochelyid Mesodermochelys undulatus and the pubis is non-diagnostic.
Fig. 2. Stratigraphic section of the outcrop studied at Algarrobo. From base to top: (Fig. 2C): 1, 2, 6, 9, fine-grained sandstones, with some concretions and differences in hardness; 3, very indurated conglomerate with rounded clasts of varying size reaching 7 cm in diameter; 4, 5, 11, fine-grained sandstones with abundant marine invertebrates; 7, conglomeratic fine-grained sandstones of moderate hardness containing marine invertebrates, fragments of wood and decapods and abundant vertebrate remains. 8, compact, very hard, fine-grained sandstones containing invertebrates, fragments of wood and some vertebrate remains. The top of this unit is permanently under the sea, so it is difficult to evaluate its thickness; 10, no exposures; The basement is comprised by intrusive rocks.
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Fig. 3. AeD, Testudines indet. A, B, neural plate MPC.11003 in A, dorsal and B, ventral views. C, D, peripheral plate MPC.11002 in C, dorsal and D, ventral views. EeG, Chelonioidea indet., MPC.11001, proximal portion of left humerus in E, ventral, F, anterior and G, dorsal views. HeP, cf. Dermochelyidae indet., SGO.PV.6573. HeK, left scapula in H, posterior, I, internal, J, external and K, anterior views. LeN, right ilium in L, lateral, right, M, acetabular and N, lateral, left views. O, P, right pubis in O, dorsal and P, ventral views. Anatomical abbreviations: afi, articular facet for the ischium; afp, articular facet for the pubis; ah, articular head; g, glenoid; mp, medial process; lp, lateral process; sp, scapular process; t, tuberosity. Scale bar represents 10 mm.
Diapsida Osborn, 1903 Plesiosauria de Blainville, 1835 Plesiosauria indet. Fig. 4A, B Material. SGO.PV.6638, incomplete left propodial. Description. SGO.PV.6638 is an incomplete propodial missing its distal end. The proximal portion is poorly preserved. The articular
surface of the head preserves a depression between the articular head and the position of the tuberosity (not preserved), indicating that this structure was relatively separate from the diaphysis. The general shape together with the position of the depression identifies it as a left propodial, but is not possible to identify it as a humerus or femur. The diaphysis appears as a longitudinal section owing to erosion suffered by its exposure to tides. The internal tissue of the bone exposed by the erosion shows that the outer surface of the diaphysis has a thicker and more compact ossification, which surrounds the depression between the head and the
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Fig. 4. Plesiosauria indet., SGO.PV.6638, left propodial in A, ventral and B, dorsal views. Scale bar represents 10 cm.
tuberosity. The head and the tuberosity have a less compact, porous ossification. Considering the small size of the preserved bone and the poor development of the articular head, SGO.PV.6638 could belong to a juvenile individual. The bone has associated a partial valve of C. acuticostatum. Remarks. The short, stout propodial SGO.PV.6638 has been regarded as typical of young plesiosaurs (Brown, 1981). The preserved portion does not allow further determination. Elasmosauridae Cope, 1869 Elasmosauridae indet. Figs. 5AeI, 6AeJ Material. SGO.PV.90, 21 articulated vertebrae SGO.PV.6572, 17 isolated teeth (Fig. 6AeJ).
(Fig.
5AeI);
Description. The 21 articulated vertebrae (SGO.PV.90, Fig. 5A) correspond to most of the anterior portion of the trunk and six posteriormost cervicals. Anterior preserved vertebrae have their neural arches laterally crushed on the right side, while the dorsal elements retain their right transverse processes without deformation or displacement, although the left side of their neural arches are crushed. The cervical vertebrae have an oval, flattened articular face (Fig. 5B). Ventrally, the cervicals show two ventral foramina, broad an elliptical in shape, without a sharp ventral keel between them (Fig. 5C). The cervical rib facets observed in the two anteriormost
preserved centra are positioned ventrally and occupy a central position in lateral view. The transition from cervicals to dorsals is at the seventh preserved vertebra. Starting at this vertebra, the rib attachment is placed in the transverse processes of the neural arch and the vertebrae have circular articular faces (Fig. 5D), being slightly amphicoelous, and becoming medially constrained in ventral view (Fig. 5E). The fourth and the fifth vertebrae have an ‘8-shaped’ rib facet placed in the centrum itself, but in a very dorsal position, while the sixth has a facet axially enlarged in the dorsal portion but ventrally reduced (Fig. 5F). Regarding the dorsal vertebrae, in ventral view, the eleventh and twelfth centra have a pair of additional small foramina (less than 5 mm) on each side (Fig. 5G) and positioned symmetrically, while the other dorsal elements retain only two oval, large foramina as observed in the anterior elements (Fig. 5H). The vertebrae 6e21 preserve the neural arches, and the posteriorly recurved transverse processes are high and thick. The block containing the fifteenth to nineteenth vertebrae preserves laterally crushed neural spines in their natural position (Fig. 5I). The measurements of each centra are provided in Table 1. In addition to the articulated vertebrae (SGO.PV.90), there are 17 isolated teeth (SGO.PV.6572) that can also be identified as elasmosaurids (Fig. 6AeH). These include both well-preserved teeth and incomplete crowns of variable size, with rare large examples. The crowns of these teeth are slender and very sharp, with a convex lingual surface, having longitudinal striations that fade near the base of the crown. The labial surfaces are flattened and variably convex according to the anatomic position of each tooth. In all cases the teeth show several ridges and enamel
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Fig. 5. Elasmosauridae indet., SGO.PV.90. A, cervical and dorsal vertebral sequence in right view. B, C, anteriormost preserved cervical vertebra in articular and ventral views respectively. D, E, first dorsal vertebra (seventh preserved) in articular and ventral views respectively. F, detail of the fifth to eighth preserved vertebrae, showing the outline transition of the rib facet from the posterior cervicals to the anteriormost dorsals. G, ventral view of the eleventh and twelfth preserved vertebrae, with the ventral foraminae digitally enhanced for clarification. H, ventral view of the block containing the fifteenth to nineteenth preserved, dorsal vertebrae. I, left view of the same block, showing the neural spines as well as the transverse processes. Scale bar represents 100 mm.
cracking, while all the crowns are strongly recurved lingually. The alveolar end is hollow and the root walls are variable in thickness, evidencing easy removal. One tooth shows a lateral scar-like notch, probably caused by the synchronous growth of this and an adjacent, partially overlapped tooth, making it possible to observe two “facets” that are consistent with the lateral cast of a tooth. A different notch pattern is present on the other side of the same sample, distinguished by a unique “facet” with wellmarked striations, which suggest wearing between upper and lower teeth in the occlusion (Fig. 6F, G). The thicker growth at the tip of the crown (Fig. 6H) suggests that this element grew while it was constrained by an adjacent tooth, since wearing by occlusion could only explain the lateral, single “facet” notch, but not the thickening observed near the top end of the latter, which should
appear also wasted since this portion is slightly more prominent than the rest of the crown and evidently should have been more affected by wearing. These features suggest a reduced distance between alveoli. Remarks. The preserved centra (SGO.PV.90) shows two ventral foramina, a character present only in pistosaurs and plesiosaurs (O’Keefe, 2001). Additionally, the anteriormost element preserved corresponds to a cervical posterior vertebra with an oval shape in articular view. This reflects the gradual loss of the ventral notch in posterior cervicals, while the middle cervicals have a well-developed notch. This notch is considered an apomorphic character of elasmosaurids (Bardet et al., 1999; Gasparini et al., 2003).
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Fig. 6. AeH, Elasmosauridae indet., SGO.PV.6572, selected teeth of different individuals. AeD, from left to right in labial, profile, lingual and basal views, respectively. E, tooth with lateral notch, from left to right in labial, profile, lingual and opposite profile views. F, detail of same tooth showing the labial and lingual change of facet of a probable adjacent tooth. G, detail of the same tooth showing marked striations, probably an effect of wearing. H, detail of the same tooth showing a thicker growth at the tip caused by the constraining of the crown. I, J, Mosasauridae indet. I, SGO.PV.6570, isolated tooth, from left to right in labial, lingual, anterior and posterior views, respectively. J, SGO.PV.6571, selected tooth, from left to right in labial, lingual, anterior and posterior views, respectively. Scale bars represent 10 mm in AeD, IeJ, 5 mm in FeH.
SGO.PV.90 also shows clear sutures between neural arches and their respective centra. The presence of such sutures is thought to be indicative of juvenile individuals (Brown, 1981; Gasparini et al., 2003). The transitional centra from cervicals to dorsals displays “8-shaped” rib facets (Fig. 5F) that are not observed in other mature elasmosaurid specimens from Chile (e.g., SGO.PV.91 and 92). Regarding the teeth (SGO.PV.6572), all the mentioned morphologies have been described in other Late Cretaceous
elasmosaurid plesiosaurs, such Tuarangisaurus keyesi Wiffen and Moisley, 1986 and Terminonatator pointeixensis Sato, 2003. Squamata Oppel, 1811 Mosasauridae Gervais, 1853 Mosasauridae indet. Fig. 6I, J Material. SGO.PV.6570, one isolated tooth; SGO.PV.6571, three isolated crowns.
Table 1 Measurements of the vertebral centra of SGO.PV.90. Vertebra number
Height (mm)
Breadth (mm)
Length (mm)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
66.9 67.2 66.8 66.3 74.6 e 81.4 e 78.1 e 84.9 e 86.6 e 86.7 e e e e e e
100.8 100.8 101.4 99.8 97.7 96.6 100.2 95.2 93.7 92.7 85.1 94.3 92.5 95.8 96.6 91.6 e 92.6 93.6 e 92.7
66.0 66.8 67.1 68.2 66.4 69.5 76.6 72.3 78 74.7 72.1 71.1 73.8 72.4 74 73.2 71.1 68.7 69.1 65.4 e
Description. SGO.PV.6570 has a slender, relatively high crown, lacking its top, with profuse fine striations over the labial and lingual surfaces (Fig. 6I, J), being slightly stronger on the latter. It displays three well-marked constrictions along the basal portion of the crown (Fig. 6I). The lingual and labial surfaces are distinguished by the presence of a dull anterior carina without serrations or a sharp cutting edge. No carina is observed on the posterior edge. The lingual face is concave while the labial face is convex, and without any facets. The three additional teeth of mosasaurs (SGO.PV.6571) share a similar morphology but are very small. They differ from SGO.PV.6570 in having shorter crowns, no basal constrictions, and a posterior carina on the posterior edge, diminishing into the base of the crown. SGO.PV.6570 and SGO.PV.6571 are consistent in size and morphology with teeth observed in a small mandible recovered at Cocholgüe, Q.315 (unpublished). SGO.PV.6570 has closer affinities with anterior teeth of the left dentary of Q.315, while SGO.PV.6570 teeth are very similar to the posterior teeth preserved in the right
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dentary of this specimen. Their fragmentary preservation does not permit a more-detailed comparison. Remarks. The presence of discrete sockets (alveoli) for the attachment and insertion of the teeth, and the ossified, filled spaces between teeth (interdental tissues composed of alveolar bone) are common characters of Squamata such as mosasaurs (Caldwell et al., 2003; Caldwell, 2007). SGO.PV.6570 preserves part of the cementum tissue attached to the base of the crown that would have formed part of the root of the tooth. Considering the morphology of the specimens recovered, these teeth could all belong to the same taxon, although no generic or specific identification can be proposed owing to their fragmentary condition. 4. Discussion 4.1. Biogeographic implications The Late Cretaceous reptiles from Algarrobo add to an emerging picture of Maastrichtian marine reptile faunas of the Weddellian Biogeographic Province and the Pacific Basin. For example, the presence of elasmosaurid plesiosaurs is rather typical of Weddellian faunas during the Maastrichtian (Gasparini et al., 2003, 2007). This is in contrast to the known record of the group during the Early Cretaceous when elasmosaurids were scarce in Southern Hemisphere (Kear, 2007). Since the Aptian, the elasmosaurids were present in the Pacific Basin (Welles, 1952; Sato et al., 2006) reaching a cosmopolitan distribution in the latest Cretaceous along the Weddellian Biogeographic Province and the Northern Hemisphere. The presence of cf. Dermochelyidae, though tentative, may reaffirm a connection between Weddellian and North Pacific marine reptile assemblages that existed at least since Campanian time. Dermochelyids are well known from Maastrichtian localities in Japan (Hirayama and Chitoku, 1996; Hirayama et al., 2006). If dermochelyids do occur at Algarrobo then it would be one more point of faunal similarity. As Weddellian marine tetrapod faunas become better known they will provide a sounder basis of comparison to other Late Cretaceous marine faunas in the Pacific Basin and beyond. 4.2. Ecological implications The reptile fossils occur with abundant elasmobranch remains with close affinities to the genus Hypolophodon (Myliobatiformes, Dasyatidae), regarded as an inhabitant of shallow marine waters with tolerance to salinity and an ability for invading deltas and estuarine environments (Murray et al., 2010). Similarly, smallbodied mosasaurs like those found in Algarrobo, were considered by Jacobs et al. (2005) to inhabit a range of environments from intertidal to shallow marine waters, having tolerance of brackish as well as normal marine salinities. Additionally, the presence of juvenile plesiosaurs at Algarrobo suggests that this environment may have been preferred by certain early stages in the life of elasmosaurids, (Wiffen et al., 1995; Salgado et al., 2007), though that remains to be tested through additional discoveries. Finally, the presence of glauconite is informative, since it is often considered as indicative of marine continental shelf environments where deposition occurs at slow rates (Kazakov, 1982). Combined with the occurrence of terrestrial input (frequent carbonized wood remains), we can reconstruct the palaeoenvironment of Algarrobo as a shallow, continental shelf near an estuary. Acknowledgments D. Rubilar-Rogers and R. Otero were supported by the Antarctic Ring Project (ACT-105-Conicyt). J.F. Parham was supported by the
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Remington Kellogg Fund and funding from the Smithsonian Institution to N.D. Pyenson. R. Otero was authorized by the Consejo de Monumentos Nacionales (National Monuments Council, Chile) in March 2006 to collect fossil samples. P. Jimenez-Huidobro thanks M.W. Caldwell for comments provided during the review process. We all thank M.E. Suárez (Museo Paleontológico de Caldera, Atacama, Chile) for providing access to three of the specimens studied.
References Bardet, N., Godefroit, P., Sciau, J., 1999. A new elasmosaurid plesiosaur from the Lower Jurassic of southern France. Palaeontology 42, 927e952. Batsch, A.J., 1788. Versuch einer Anleitung, zur Kenntiniß und Geschichte der Tiere und Mineralien. Akademische Buchhandlung, Jena, 528 pp. Baur, G., 1893. Notes on the classification of the Cryptodira. American Naturalist 27, 672e674. Biró-Bagóczky, L., 1982. Revisión y redefinición de los ‘Estratos de Quiriquina’, CampanianoeMaastrichtiano, en su localidad tipo, en la Isla Quiriquina, 36 370 Lat. Sur, Chile, Sudamérica, con un perfil complementario en Cocholgüe. III Congreso Geológico Chileno, Actas Vol. 1, Concepción, pp. A29eA64. de Blainville, M.H.D., 1816. Prodrome d’une nouvelle distribution systematiques du regne animal. Bulletin de la Société Philomathique de Paris 8, 113e124. de Blainville, M.H.D., 1835. Description de quelques espèces de reptiles de la Californie précédé de l’analyse d’un système général d’erpétologie et d’amphibiologie. Nouvelles Annales du Muséum d’Histoire Naturelle de Paris, Série 3e4, 233e296. Brito, P.M., Suárez, M.E., 2003. Late Cretaceous Belonostomus (Pisces, Actinopterygii, Aspidorhynchidae) from Algarrobo, Chile, with comments on aspidorhynchid paleodistribution in South America. Revista Geológica de Chile 30, 117e127. Brown, D., 1981. The English Late Jurassic Plesiosauroidea (Reptilia) and review of the phylogeny and classification of the Plesiosauria. Bulletin of the British Museum (Natural History), Geology 4, 225e234. Brüggen, J., 1915. El Cretáceo de Algarrobo. Sociedad Imprenta Litográfica Barcelona, Santiago-Valparaíso, 15 pp. Caldwell, M.W., 2007. Ontogeny, anatomy and attachment of the dentition in mosasaurs (Mosasauridae: Squamata). Zoological Journal of the Linnean Society 149, 687e700. Caldwell, M.W., Budney, L.A., Lamoureux, D.O., 2003. Histology of tooth attachment tissues in the Late Cretaceous mosasaurid Platecarpus. Journal of Vertebrate Paleontology 23, 622e630. Cecioni, G., 1955. Distribuzione verticale di alcune Kossmaticeratidae della Patagonia cilena. Societá Geológica Italiana, Bolettino 74, 141e148. Cecioni, G., 1980. Darwin’s Navidad Embayment, Santiago Region, Chile, as a model of the southeastern Pacific shelf. Journal of Petroleum Geology 2, 309e321. Cecioni, G., 1983. Chanco Formation, a potential Cretaceous reservoir, central Chile. Journal of Petroleum Geology 6, 89e93. Cope, E.D., 1869. On the reptilian orders Phytonomorpha and Streptosauria. Proceedings of the Boston Society of Natural History 12, 250e266. Gana, P., Tosdal, R., 1996. Geocronología U-Pb y K-Ar en intrusivos del Paleozoico y Mesozoico de la Cordillera de la Costa, Región de Valparaíso, Chile. Revista Geológica de Chile 23, 151e164. Gana, P., Wall, R., Gutiérrez, A., 1996. Mapa Geológico del área de ValparaísoCuracaví, Región de Valparaíso y Región Metropolitana. Servicio Nacional de Geología y Minería, Mapas Geológicos N 1, Escala 1:100.000. Santiago, 20 pp. Gasparini, Z., 1979. Comentarios críticos sobre los vertebrados mesozoicos de Chile. Congreso Geológico Chileno, No 2, Actas 3, pp. H15eH32. Gasparini, Z., 2007. Plesiosauria. In: Gasparini, Z., Salgado, L., Coria, R. (Eds.), Patagonian Mesozoic Reptiles. Indiana University Press, Bloomington, IN, pp. 292e313. Gasparini, Z., Biró-Bagoczky, L., 1986. Osteopygis sp. (Reptilia, Testudines, Toxochelyidae). Tortuga Fósil de la Formación Quiriquina, Cretácico Superior, Sur de Chile. Nota Paleontológica, Revista Geológica de Chile 27, 85e90. Gasparini, Z., Goñi, R., 1985. Los plesiosaurios cretácicos de América del Sur y del continente antártico. Congresso Brasileiro de Paleontología, No. 8. Coletanea de Trabalhos Paleontológicos, Serie Geologie 27, 55e63. Gasparini, Z., Bardet, N., Martin, J., Fernandez, M., 2003. The elasmosaurid plesiosaur Aristonectes Cabrera from the latest Cretaceous of South America and Antarctica. Journal of Vertebrate Paleontology 23, 104e115. Gasparini, Z., Salgado, L., Parras, A., 2007. Late Cretaceous plesiosaurs from northern Patagonia, Argentina. Geological Journal 42, 185e202. Gervais, P., 1853. Observations relatives aux reptiles fossiles de France. Comptes Rendus de l’Académie des Sciences de Paris 36, 374e377, 470e474. Hiller, N., Mannering, A., Jones, C., Cruickshank, A., 2005. The nature of Mauisaurus haasti Hector, 1874 (Reptilia: Plesiosauria). Journal of Vertebrate Paleontology 25, 588e601. Hirayama, R., 1994. Phylogenetic systematics of chelonioid sea turtles. Island Arc 3, 270e284. Hirayama, R., Chitoku, T., 1996. Family Dermochelyidae (Superfamily Chelonioidea) from the Upper Cretaceous of North Japan. Transactions and Proceedings of the Palaeontological Society of Japan, New Series 184, 597e622.
132
R.A. Otero et al. / Cretaceous Research 35 (2012) 124e132
Hirayama, R., Fujii, A., Takahashi, K., 2006. A dermochelyid sea turtle from the Upper Cretaceous (Late Campanian) Izumi Group of Shionoe, Takamatsu City, Kagawa Prefecture, western Japan. Fossils 80, 17e20. Jacobs, L.L., Polcyn, M.J., Taylor, L.H., Ferguson, K., 2005. Sea-surface temperatures and palaeoenvironments of dolichosaurs and early mosasaurs. Netherlands Journal of Geosciences, Geologie en Mijnbouw 84, 269e281. Joyce, W.G., Parham, J.F., Gauthier, J., 2004. Developing a protocol for the conversion of rank-based taxon names to phylogenetically defined clade names, as exemplified by turtles. Journal of Paleontology 78, 989e1013. Katz, H., 1963. Revision of Cretaceous stratigraphy in Patagonian Cordillera of Última Esperanza, Magallanes province, Chile. American Association of Petroleum Geologists, Bulletin 47, 506e524. Kazakov, G.A., 1982. Glauconites as geochemical indicators of facies conditions of sediment genesis. Geochemistry International 19, 1e14. Kear, B., 2007. Taxonomic clarification of the Australian elasmosaurid genus Eromangasaurus, with references to other austral elasmosaur taxa. Journal of Vertebrate Paleontology 27, 241e246. Laurenti, J.N., 1768. Specimen medicum, exhibens synopsin reptilium emendatam cum experimentis circa venena et antidota reptilium austracorum, quod authoritate et consensu. Thomae, Vienna, 217 pp. Lehman, T., Tomlinson, S., 2004. Terlinguachelys fishbecki, a new genus and species of sea turtle (Chelonioidea: Protostegidae) from the Upper Cretaceous of Texas. Journal of Paleontology 78, 1163e1178. Levi de Valenzuela, B., Aguirre, L., 1966. El Conglomerado de Algarrobo y su relación con las formaciones del Cretácico Superior de Chile Central. Instituto de Investigaciones Geológicas (Chile) 17, 417e431. Martin, J., Sawyer, F., Reguero, M., Case, J., 2007. Occurrence of a young elasmosaurid plesiosaur skeleton from the Late Cretaceous (Maastrichtian) of Antarctica. In: Cooper, A.K., Raymond, C., Anderson, J., Barrett, P., Barron, J., Bart, P., Blankenship, D., Cooper, A., Davey, F., Diggles, M., Finn, C., Fitzgerald, P., Florindo, F., Francis, J., Futterer, D., Gamble, J., Goodge, J., Hammer, W., Helton, P., Ivins, E., Kyle, P., LeMasurier, W., Mayewski, P., Naish, T., Passchier, S., Pekar, S., Raymond, C., Ricci, C., Stagg, H., Storey, B., Stump, E., Studinger, M., Sugden, D., Thorn, V., Wilson, T., Wise, W. (Eds.), Antarctica: A Keystone in a Changing World. Online Proceedings of the 10th International Symposium of Antarctic Earth Sciences. United States Geological Survey, Open-File Report 20071047, Short Research Paper 066, Santa Barbara, California, pp. 1e4. Available at: http://pubs.usgs.gov/of/2007/1047/ srp/srp066/of2007-1047srp066.pdf. Murray, A.M., Cook, T.D., Attia, Y.S., Chatrath, P., Simons, E.L., 2010. A freshwater ichthyofauna from the late Eocene Birket Qarun Formation, Fayum, Egypt. Journal of Vertebrate Paleontology 30, 665e680. O’Keefe, F.R., 2001. A cladistic analysis and taxonomic revision of the Plesiosauria (Reptilia: Sauropterygia). Acta Zoologica Fennica 213, 1e63. Oppel, M., 1811. Die Ordnung, Familien und Gattung der reptilien als Prodrom einer Naturgeschichte derselben. München, 87 pp. d’Orbigny, A., 1842. Voyage dans l’Amerique méridionale. In: Paléontologie, Vol. 3(4), p. 187. Osborn, H.F., 1903. The reptilian subclasses Diapsida and Synapsida and the early history of the Diaptosauria. Memoirs of the American Museum of Natural History 1, 451e507. Otero, R.A., Rubilar-Rogers, D., 2010. Nuevos restos de plesiosaurios elasmosáuridos del Cretácico Superior (Maastrichtiano) de Puerto Natales, Región de Magallanes, con comentarios sobre la procedencia estratigráfica de los registros previos en el área. In: Rubilar, A., Palma-Heldt, S. (Eds.), II Simposio e Paleontología en Chile. Libro de Actas, Concepción, p. 56. Otero, R.A., Suárez, M.E., Le Roux, J.P., 2009. First record of elasmosaurid plesiosaurs (Sauropterygia: Plesiosauria) in upper levels of the Dorotea Formation, Late Cretaceous (Maastrichtian), Puerto Natales, Chilean Patagonia. Andean Geology 36, 342e350. Parham, J.F., Stidham, T.S., 1999. Late Cretaceous sea turtles from the Chico Formation of California. PaleoBios 19, 1e7.
Pérez-D’Angelo, E., Reyes, R., 1978. Las trigonias del Cretácico Superior de Chile y su valor cronoestratigráfico. Instituto de Investigaciones Geológicas (Chile), Boletín 34, 1e74. Pérez-D’Angelo, E., Reyes, R., 1980. Buchotrigonia (Buchotrigonia) topocalmensis (Trigoniidae; Bivalvia) del Cretácico Superior de Chile. Revista Geológica de Chile 9, 37e55. Philippi, R.A., 1887. Los Fósiles Terciarios i Cuartarios de Chile. F.A. Brockhaus, Leipzig, 236 pp. Salgado, L., Fernández, M., Talevi, M., 2007. Observaciones histológicas en reptiles marinos (Elasmosauridae y Mosasauridae) del Cretácico Tardío de Patagonia y Antártida. Ameghiniana 44, 513e523. Sato, T., 2003. Terminonatator ponteixensis, a new elasmosaur (Reptilia: Sauropterygia) from the Upper Cretaceous of Saskatchewan. Journal of Vertebrate Paleontology 23, 89e103. Sato, T., Hasegawa, Y., Manabe, M., 2006. A new elasmosaurid plesiosaur from the Upper Cretaceous of Fukushima, Japan. Palaeontology 49, 467e484. Stinnesbeck, W., 1986. Zu den Faunistischen und Palökologischen Verhältissen in der Quiriquina Formation (Maastrichtium) Zentral-Chiles. Palaeontographica Abteiling A 194, 99e237. Stinnesbeck, W., 1996. Ammonite extinctions and environmental changes across the Cretaceous-Tertiary boundary in central Chile. In: Macleod, N., Keller, G. (Eds.), The Cretaceous-Tertiary Boundary Mass Extinction: Biotic and Environmental Events. Norton Press, New York, NY, pp. 289e302. Suárez, M.E., 1999. Un esqueleto postcraneal de plesiosaurio del Cretácico Superior de la Formación Quiriquina, VIII Región, Chile. Jornadas Argentinas de Paleontología de Vertebrados N 15, La Plata, Argentina. Ameghiniana 36, 22R. Suárez, M.E., Cappetta, H., 2004. Sclerorhynchid teeth (Neoselachii, Sclerorhynchidae) from the Late Cretaceous of the Quiriquina Formation, central Chile. Revista Geológica de Chile 31, 89e103. Suárez, M.E., Marquardt, C., 2003. Revisión preliminar de las faunas de peces elasmobranquios del Mesozoico y Cenozoico de Chile. Congreso Geológico Chileno n 10, Sesión temática 3, Paleontología. Actas, CDROM. Universidad de Concepción, Concepción, 9 pp. Suárez, M.E., Otero, R.A., 2009. Nuevos hallazgos de vertebrados marinos en el CampanianoeMaastrichtiano de Loanco, VII Región. In: Rubilar, A., RubilarRogers, D., Gutstein, C. (Eds.), I Simposio Paleontología en Chile. Libro de Actas, Santiago, pp. 78e82. Suárez, M.E., Quinzio, L., Fritis, O., Bonilla, R., 2003. Aportes al conocimiento de los vertebrados marinos de la Formación Quiriquina. Congreso Geológico Chileno n 10, Sesión temática 3, Paleontología. Actas, CDROM. Universidad de Concepción, Concepción, 7 pp. Tavera, J., 1980. Cretáceo y Terciario de la localidad de Algarrobo. Imprentas Gráficas, Santiago, 45 pp. Tavera, J., 1988. Formación Quiriquina. Localidades para la formación. Estratotipos y fauna (latitudes 33 210 e37 500 ). Unpublished monograph, Departamento de Geología, Universidad de Chile, 212 pp. Welles, S.P., 1952. A review of the North American Cretaceous elasmosaurs. University of California Publications in Geological Sciences 29, 46e144. Wiffen, J., Moisley, W., 1986. Late Cretaceous reptiles (families Elasmosauridae, Pliosauridae) from the Mangahouanga Stream, North Island, New Zealand. New Zealand Journal of Geology and Geophysics 29, 205e252. Wiffen, J., de Buffrénil, V., de Ricqlès, A., Mazin, J.-M., 1995. Ontogenetic evolution of bone structure in Late Cretaceous Plesiosauria from New Zealand. Geobios 28, 625e640. Zinsmeister, W.J., 1979. Biogeographic significance of the late Mesozoic and early Tertiary molluscan faunas of Seymour Island (Antarctic Peninsula) to the final breakup of Gondwanaland. In: Gray, J., Boucot, A. (Eds.), Historical Biogeography, Plate Tectonics, and Changing Environment. Proceedings of the Annual Biological Colloquium and Selected Papers. Oregon State University Press, Corvallis, OR, pp. 349e355. Zinsmeister, W.J., 1982. Late Cretaceouseearly Tertiary molluscan biogeography of southern Circum-Pacific. Journal of Paleontology 56, 84e102.
