Your Friends The Titanosaurs, part 36.2: Coming Attractions (Europe and South America)

Here we go: Apart from next month's wrap-up (and anything that gets named before then), this is the last time down the titanosaurian rabbit hole. We're going to visit the unnamed titanosaurs of Europe and South America, complementing the visit last time to the rest of the world. Some of the best examples are in this post, such as MAU-Pv-LI-595, MAU-Pv-AC-01, and MUCPv-1533, all from the vicinity of Rincón de los Sauces/La Invernada.

Note: This is another long one. On the other hand, it's split into many paragraph-sized chunks, so it's good for skipping around.

Europe

Bulgaria: The potential titanosaurian record of Bulgaria is limited at this time to U.S., K[2 subscript]1586 and NMNHS FR-16, two bone fragments. The specimens were found in a gully known as Vrabchov dol in the western border of Bulgaria, in an area mapped as the Rezhantsi Formation and tentatively dated to the early Santonian–early Campanian. They are of limited informative value and had to be studied by thin sections to yield a tentative classification (Nikolov et al. 2020).

Figure 3 from Nikolov et al. (2020). The caption reads "Fossilized bone fragments for the Vrabchov dol. 1, Multiple views of specimen U.S., K21586, an undetermined long bone diaphyseal fragment; 2. Specimen NMNHS FR-16, possibly a partial diaphysis of undetermined long bone. Scale bar equals 3 cm. CC BY 4.0.

France: Titanosaur bits and bones have been found in France for a long time (wave to the people, Hypselosaurus). One of the more unusual unnamed forms is the Massecaps titanosaur, from Massecaps in Hérault, Occitanie. It is best known from robust, somewhat spatulate teeth, not quite as spatulate as Ampelosaurus teeth but certainly not the stereotypical titanosaur teeth (Díez Díaz et al. 2013). Skull bones (a partial braincase, two partial skull roofs, and teeth) of two titanosaur species have been found at Fox-Amphoux-Métisson in Var, Provence-Alpes-Côte d'Azur (Díez Díaz et al. 2012).

Hungary: Ősi et al. (2017) described an unusual tooth from the Santonian Csehbánya Formation of Iharkút, western Hungary. This tooth resembles those of non-titanosaurian titanosauriforms (including brachiosaurs) and the basal titanosaur Sarmientosaurus.

The Hungarian titanosauriform tooth. Figure 2 in Ősi et al. (2017). The caption is "Basal titanosauriform tooth (MTM PAL 2017.1.1.) from the Santonian of Iharkút, Hungary. (A) apical, (B) lingual, (C) labial, (D) mesial, (E) distal, (F) oblique distolingual, and (G) basal views. Abbreviations: bap, broken apex of the crown; cla, convex labial surface; cli, slightly concave lingual surface; pc, pulp cavity; re, rounded edge; sc, scratch." CC BY 4.0.

Italy: Three bones from late Aptian–early Albian rocks of central Italy have been attributed to titanosaurs: an anterior caudal (MSNM V7157), a fragment of scapular blade or ischial or pubic shaft (MSNM V7158), and a possible pelvic fragment (MSNM V7159). Only the caudal, thought to have been a fifth to eighth caudal, is particularly complete and informative. It is quite unusual in that the prezygapophyseal facets (the surfaces where the prezygapophyses articulate with the caudal in front of them) face mediodorsally (internally and up) instead of medioventrally (internally and down), and the corresponding postzygapophyseal facets are oriented laterodorsally (outside and up) instead of lateroventrally (outside and down). This is important because not only is this not seen in any other sauropods, it isn't known in any other terrestrial vertebrates, either (Dal Sasso et al. 2016). Clearly it would interesting to get more of this unusual form.

Romania: As related in recent abstract form (Mannion et al. 2019a), reanalysis of Romanian titanosaur material indicates the presence of three or four distinct species: Magyarosaurus dacus, "M." hungaricus, Paludititan nalatzensis (can be distinguished from M. dacus but cannot be compared to "M." hungaricus due to no overlapping material), and an unnamed large-bodied titanosaur known from a "poorly preserved partial skeleton". Attributed questionably to Magyarosaurus is a braincase and skull roof from Pui (LPB-FGGUB R. 1007) (Weishampel et al. 1991; Díez Díaz et al. 2012).

Spain: The Algora site (central Spain), in the Cenomanian Arenas de Utrillas Formation, has yielded titanosaur fossils indicating an animal related to the owner of the Italian caudal MSNM V7157. The bones include an almost complete dorsal rib, two rib fragments, three caudals, a caudal neural arch, a chevron, a sternal plate, a right ulna, a left metacarpal II, a left ischium, and a right fibula. These were all found in an area of about 10 square meters and are consistent with belonging to one small-to-medium titanosaur. The similarities to the unnamed Italian taxon imply some connection between Laurasia and the Adriatic Plate (hosting Italy) (Mocho et al. 2019).

Mocho et al. (2019) also briefly mentioned specimens previously mooted as late Early Cretaceous Spanish sauropods, such as an anterior caudal from the Camarillas Formation of Galve with a posterior ball and a femur from the Arcillas de Morella Formation of Cincotorres. However, they cautioned that the putative titanosaur features recognized in these specimens were more widely distributed among titanosaurs.

As mentioned in the Lohuecotitan pandafilandi entry, the Lo Hueco site (Villaba de la Sierra Formation, late Campanian–early Maastrichtian) has at least two titanosaur taxa, one of which is L. pandafilandi and one of which isn't. In the interest of space I am omitting a full account of the relevant publications, because it seems like every paper that mentions the sauropod bones reports this observation. Here are a few to get you started should you decide to investigate, though: Díez Díaz et al. (2015, 2016), Knoll et al. (2015), Ortega et al. (2015) (with photos of several partial sauropod specimens) and Páramo et al. (2020). The site has yielded more than 10,000 fossils, about half of which are from titanosaurs, and there are more than 20 portions of skeletons representing several individuals. Differences include an Ampelosaurus-like braincase versus a more Jainosaurus-like braincase, robust teeth versus more delicate teeth, and two distinct forms of appendicular bones (Ortega et al. 2015). Díez Díaz et al. (2015) also suggested the presence of two titanosaurs at the Chera site in Valencia (late Campanian–early Maastrichtian Sierra Perenchiza Formation): Lirainosaurus cf. astibiae and something else.

Figure 1 from Knoll et al. (2015), showing the partial skeleton that yielded braincase MCCM-HUE-1667. CC BY 4.0.

United Kingdom: The two-plus titanosaur caudals catalogued as NHMUK R5333 made a brief appearance earlier. They represent a bona fide Wealden titanosaur (Upchurch et al. 2011; D'Emic 2012; Mannion et al. 2013, 2019b), of interest in showing the geographic distribution of early titanosaurs.

South America: Argentina

Not only are there enough of these to give Argentina its own section, there are enough that we can do this in rough stratigraphic order, from oldest to youngest. (Incidentally, the "Santa Rosa indet" of Curry-Rogers 2005 is Bonatitan reigi, right? Fits the geologic age, has cranial material, comes from Bajo de Santa Rosa, although named in 2004 may have come too late for a 2005 book...)

MOZ-Pv 1221: Here's a good old-fashioned giant titanosaur. MOZ-Pv 1221, described in Otero et al. (2021) comes out of the Cenomanian–Turonian Candeleros Formation of Neuquén Province, also known for Andesaurus delgadoi and rebbachisaurs (and, I suppose, some theropods). MOZ-Pv 1221 is not Andesaurus, being much more derived (perhaps a basal lognkosaur). It is known from 24 caudals, associated chevrons, and some yet-to-be-collected appendicular bones (much of the hip and left scapula plus others). Twenty of the caudals make up one sequence consisting of caudals 1 through 20, and the other four belong farther back. The uncollected appendicular bones are larger than any other described titanosaur appendicular bones. This sauropod can be distinguished from most of the other super-titanosaurs, but at the moment there is no overlap with Argentinosaurus huinculensis from the overlying Huincul Formation (they don't plot closely in the phylogeny, though). Otero et al. (2021) refrained from naming a new genus or species, although I certainly would not be surprised if it did get a name once the other bones are collected and prepared.

MMCH-Pv 47: Otero et al. (2006) tentatively attributed caudals from the upper Candeleros Formation near Villa El Chocón in Neuquén Province to Andesaurus, also found in that formation and in that same area. Later study indicated that the fossils, catalogued as MMCH-Pv 47 (nine caudals in two groups with seven chevrons), could not definitely be assigned to Andesaurus (Mannion and Calvo 2011; Otero et al. 2011), although to be fair they are not too extravagantly dissimilar. They are noted for being amphicoelous with neural arches that are flared anteriorly–posteriorly, and chevrons transitioning from a fairly normal chevron shape to something that looks like a moaning ghost. (It should be mentioned that Otero et al. 2021 were dubious about this specimen being a titanosaur.)

Bajo Barreal Formation titanosaurs: On page 58 of the description of Sarmientosaurus musacchioi (Martínez et al. 2016), there is a discussion of various unnamed titanosaurs from the Cenomanian–Turonian Bajo Barreal Formation. Among the specimens mentioned are: an Andesaurus-like caudal sequence; another caudal sequence plus chevrons and femur that do not belong to fellow Bajo Barreal titanosaur Epachthosaurus sciuttoi; and premaxilla and maxilla bones that do not belong to Sarmientosaurus. It is entirely possible that some of these represent otherwise unknown pieces of the titanosaur that hasn't been ruled out, but only more specimens can confirm or disprove this idea.

Figure 31 from Martínez et al. (2016) shows skull material from UNPSJB-PV 699 (premaxilla, lateral [A] and medial [B]) and UNPSJB-PV 583 (maxilla, lateral [f], medial [g], and ventral [h]) from the Bajo Barreal Formation, plus the type material of "Campylodon" ameghinoi. Scale is 5 cm in A–E and 10 cm in F–H. CC BY 4.0.

MUCPv-319: In Wilson et al. (2019:21) we learn the following: "A beautifully preserved, undescribed anterior dorsal vertebra from the Portezuelo Formation of Argentina housed at the Centro Paleontológico Lago Barreales (MUCPv-319; Calvo and Bellardini, 2011) is an excellent match for GSI/GC/OGF107." This is of note because GSI/GC/OGF107 is a dorsal vertebra from India, as we saw last time. Wilson et al. (2019) suggested that MUCPv-319 might belong to Mendozasaurus.

MCF-PVPH-889, -899, and -900: Bellardini et al. (2018) described a small group of bones from the Coniacian–Santonian Plottier Formation near Plottier in Neuquén Province, including a femur (MCF-PVPH-889/02), fibula (-900), ?tibia (-899), and dorsal ribs (-889/01). Although all of them were found near each other, Bellardini et al. (2018) preferred not to associate them as one individual, especially when the purported tibia was notably smaller than the other limb elements. The femur is incomplete, with the preserved portion measuring a healthy 190 cm long (74.8 in), while the complete fibula measures 114 cm long (44.9 in). The two bones are similar to but not exactly the same as bones of named Plottier Formation titanosaurs.

MAU-Pv-N-414: Another unnamed titanosaur from the Plottier Formation is represented by this catalog number, consisting of four partial anterior caudals found in the upper part of the formation in the Rincón de los Sauces area of northeastern Neuquén Province. This particular taxon is an aeolosaur, otherwise not known from the formation, and is also the oldest known aeolosaur (Filippi et al. 2013; Filippi 2015).

UNCUYO-LD 313: The Plottier Formation does not end there. UNCUYO-LD 313, featured briefly in a few publications (e.g., González Riga et al. 2015, 2016, 2019), hails from the Plottier Formation of the Agua del Padrillo area, Mendoza. Also known as the Agua del Padrillo taxon, it is of greatest interest for its complete hind feet, which have a phalangeal formula of 2-2-2-2-0 (unlike the 2-2-3-2-0 of Epachthosaurus). Some other appendicular bones are known as well for this reportedly slender taxon.

Two unnamed titanosaurs for the price of one! On the left is the left hind leg of MUCPv-1533, the La Invernada taxon. On the right is the left foot and lower leg of UNCUYO-LD 313, the Agua del Padrillo taxon. Cropped from Figure 1 in Gonzaléz Riga et al. 2019. CC-BY-4.0.

MLP 46-V III-21-2: Filippini et al. (2017) described a sacrum plus ilia from Plottier in Neuquén Province. The stratigraphy is not known but it probably came from one of three middle Upper Cretaceous formations (Sierra Barrosa, Plottier, or Bajo de la Carpa). It appears to be a standard six-sacral plus flared ilia titanosaurian sacrum, with the first dorsosacral missing. A phylogenetic analysis indicates it came from a fairly basal titanosaur.

MAU-Pv-LI-595: There are two absolute crown jewels among the undescribed titanosaur specimens of Argentina, both from the general vicinity of Rincón de los Sauces and both with skulls that are more than just braincases and/or jaws. They are specimens MAU-Pv-LI-595 and MAU-Pv-AC-01 (mentioned below). MAU-Pv-LI-595 was discovered and collected more recently than the latter, and has not escaped into the literature to any great degree, but there is the requisite conference abstract (Filippi et al. 2017), and some anatomical information for the skull can be found in a thesis (Capurro 2019). It comes from the Santonian Bajo de la Carpa Formation of La Invernada, and includes the skull (with squared-off snout) and an articulated vertebral column, ribs, and ilia from atlas to the last sacral (Filippi et al. 2017). The discovery, collection, and preparation of this specimen are documented in various posts at Paleosur (see this one for the skull). [Update, 2023/11/6: This is now Inawentu oslatus.]

MAU-Pv-CO-660: This is one of the more recent discoveries in this post, collected in 2019 from the Bajo de la Carpa Formation at Rincón de los Sauces (which might as well be called Rincón de los Titanosaurios) and just beginning to creep into abstracts (e.g., Filippi et al. 2020). It consists of a partially articulated skeleton of a small titanosaur, including axial and appendicular bones.

MCNA-PV 3136: Wilson et al. (1999) described MCNA-PV 3136, a sequence of 10 articulated distal caudals attributed to a saltasaurid (not necessarily in the sense we might think of Saltasauridae in 2021). These were found at Cañadon Amarillo in Mendoza Province, in rocks of the Río Colorado Subgroup (then just a formation); per Filippi (2015), the unit may be the Anacleto Formation. They begin as procoelous, then transition into biconvex rods without neural arches. Wilson et al. regarded the sequence as the tip of the tail, which is poorly known in titanosaurs; it is also significant in not having an extended whiplash.

MAU-Pv-AC-01: In the worldwide empire of undescribed and unnamed titanosaurs, MAU-Pv-AC-01 is the most tantalizing. Almost everything that is publicly known about this specimen is found in two abstracts (Calvo et al. 1997; Coria and Salgado 1999) and a National Geographic article that described the circumstances of its discovery (Shreeve 1997). Aside from brief mentions, it has been almost forgotten in the literature since the late 1990s. It has no cute nickname, no nomen nudum tag following it around. (The best I can do is "the Rincón de los Sauces titanosaur," which doesn't help that much because you could hang that tag on a lot of specimens, described and undescribed.) Why is it so significant? MAU-Pv-AC-01 is among the most complete sauropod specimens known, with skull, all vertebrae down to caudal #65 articulated (it's why titanosaur mounts have been given long tails), and the right arm; the left arm and the legs are missing. Per Garrido (2010), it hails from the Anacleto Formation. Even if it should happen to be the same as another Anacleto titanosaur (and the Anacleto is pretty stuffed as it is, with Antarctosaurus wichmannianus, Barrosasaurus casamiquelai, Laplatasaurus araukanicus, Loricosaurus scutatus, Narambuenatitan palomoi, Neuquensaurus australis+robustus, Pellegrinisaurus powelli, and Pitekunsaurus macayai), it bodes fair to provide a lot of information.

MACN-PV Rn 233: This specimen hails from the Campanian Angostura Colorada Formation of Río Negro Province. Unusually for a Patagonian Upper Cretaceous formation, the Angostura Colorada Formation has only one named titanosaur to date, Aeolosaurus rionegrinus, and MACN-PV Rn 233 isn't it. Instead, it's a saltasaur and apparently closer to Rocasaurus muniozi and Saltasaurus loricatus than to Neuquensaurus australis. The specimen includes four anterior-middle caudals (two with fused chevrons), four posterior caudals, and six osteoderms. Showing the saltasaur taste for pneumaticity, the chevrons are pneumatic. The osteoderms are of the "keeled oatmeal cookie" variety, and are notable for their number; few titanosaurs can be confirmed to have had more than one osteoderm. These bones were described in Zurriaguz et al. (2017); although they noted that MACN-Pv Rn 233 could be distinguished from other saltasaurs, they opted not to name it because of the limited material.

Lago Colhué Huapi Formation titanosaurs: MDT-PV 4 from the Campanian–Maastrichtian Lago Colhué Huapi Formation of Rio Chico, Chubut, is notable for its preserved sacral supraspinous ligament (Cerda et al. 2015). Ibiricu et al. (2017) described UNPSJB-Pv 1051, a partial subadult specimen from the Golfo San Jorge Basin, Chubut. The bones include a fragment of the right coracoid, a fragment of the left radius, a metacarpal, the articulated left femur, tibia, and fibula, the left astragalus, metatarsals, and a pedal phalanx. Several of the bones were strongly affected by diagenesis or portmortem distortion.

MUCPv-1533: One of the best unnamed titanosaur specimens is MUCPv-1533, which has been mentioned in a number of publications because it has one of the few complete titanosaurian hind feet. González Riga et al. (2008) provide the most detail on this specimen, albeit focused on the foot. It was collected from the Allen Formation of the La Invernada area of Neuquén in 2005. It includes caudals, complete and articulated left forelimb and hind limb, and other bones from the left side of the body, with no neck or skull. The hind foot has five metatarsals and a phalangeal formula of 2-2-2-2-0, like the Agua del Padrillo form above, with claws on the first three digits and a tiny wart of a phalanx I between the metatarsal and claw. The only bone in the ankle is the astragalus.

Other Allen Formation titanosaurs: At the moment, the Allen Formation titanosaur fauna consists of Aeolosaurus sp., Bonatitan reigi, Panamericansaurus schroederi, and Rocasaurus muniozi, which an observer might think is more than enough titanosaurs for any formation. Nobody asked the titanosaurs, though. García et al. (2008) described a braincase, MML-194 from Salitral de Santa Rosa in Río Negro Province, which is similar to that of Bonatitan. García (2013) described tooth MML-Pv 1030, also from Salitral de Santa Rosa. This particular tooth, otherwise of typical cylindrical chisel form, is notable for being the largest described titanosaur tooth at 75 mm (3 in) long. Without more of the animal, García could not determine if it came from an enormous titanosaur or a more modestly sized animal with unusually large teeth. If the former, it probably isn't one of the named Allen Formation titanosaurs. Scratches on the tooth indicate cropping habits, but the absence of pits suggest there wasn't much grit in the diet (García 2013). Meanwhile, at Salitral Moreno, not only are there fossils of Aeolosaurus and Rocasaurus, but various bones indicating the presence of as many as four other titanosaur species based on differences in caudal vertebrae and humeri (Garcia and Salgado 2013).

Other leftovers: The recognition that it is not possible to firmly attribute non-type specimens to many classic titanosaurs (Antarctosaurus, Argyrosaurus, Laplatasaurus, "Titanosaurus", etc.) has turned many specimens out of their former homes. (See for example Lydekker 1893 and Huene 1929.) Notable among these are the Field Museum leg bones (FMNH 13018, 13019, and 13020) collected in Chubut and variously attributed to Antarctosaurus (e.g., Huene 1929 for the latter two) or Argyrosaurus (e.g., Powell 2003 for all three). Mannion and Otero (2012) assigned them to Titanosauria indet. At more than 2 m (7 ft) long, FMNH 13018 is among the largest known sauropod femora (Mannion and Otero 1929).

South America: Others

Brazil: Curiously, Brazil seems to be an outstanding place to find pathologic titanosaurs. For example, there is UFRJ-DG 508-R from the Adamantina Formation, a caudal with two kinds of lesions (Barbosa et al. 2016); MPPC 00-017, an aeolosaur caudal from the São José do Rio Preto Formation with gnarly additional bone growth on the anterior surface that may have affected tail mobility (Barbosa et al. 2019); and an infected dorsal rib included in DGM 198-R, an aeolosaur specimen from Upper Cretaceous rocks in Mato Grosso (Brum et al. 2021). DGM 198-R was also among a group of fourteen unnamed specimens described in Bandeira et al. (2019), all from the Morro do Cambambe quarry but representing multiple individuals. Most of these specimens were on loan to the National Museum of Brazil at the time of the fire and are reportedly lost (Bandeira et al. 2019). A different unnamed Mato Grosso titanosaur specimen thought lost in the fire has been reported as recovered, though.

The sauropod sometimes known informally as "Sousatitan" was described in Ghilardi et al. (2016) from the early Early Cretaceous Rio Piranhas Formation of the Sousa Basin in northeastern Brazil. It is represented by DGEO-CTG-UFPE 7517, a 45-cm long (18-inch) fibula histologically determined to have come from a half-grown individual. It represents the first dinosaurian body fossil from a site noted for tracks. The original owner is thought to have been a titanosaur, which would make it among the oldest titanosaurs known from body fossils.

The Serra da Galga Formation, formerly the Serra da Galga Member of the Marília Formation, is already known for titanosaurs such as Baurutitan, Trigonosaurus, and Uberabatitan, and has its share of unassigned specimens. In fact, Baurutitan and Trigonosaurus made their first appearances in the literature as the Series C and Series B vertebrae, respectively. As mentioned in a previous entry, there is also a Series A, MCT 1487-R, consisting of an entire neck except the atlas, plus three dorsals (see Santucci and Bertini 2001 and Powell 2003 for more discussion). This is one of the more significant titanosaur specimens to be without a name at this time. The most recent consideration suggests that it belongs to either Uberabatitan or a close relative (Silva et al. 2019). Yet another series of vertebrae, CPP-393-402 (ten mid-distal caudals interrupted partway through by a biconcave followed by a biconvex pairing), was briefly described in Santucci and Bertini (2001). Silva et al. (2017) described remains of an indeterminate juvenile titanosaur from the Serra da Galga of Uberaba. The specimens included two dorsal and three caudal centra, a partial right ilium and a partial right ischium. Although it was not assigned to a taxon, it at least is not Baurutitan, and demonstrates the appearance of pneumatic features at a young age.

Gil et al. (2020) described various titanosaur specimens found in the Upper Cretaceous Cachoeira do Bom Jardim Formation near the village of Jangada Roncador, Mato Grosso State. The fossils included caudals, dorsal and sacral ribs, a partial right scapula, portions of a right humerus, ulna, radius, and metacarpal II, and portions of a right fibula. These were found at three sites and represent at least two individuals.

Chile: I commented on various unnamed Chilean titanosaurs way back in the Atacamatitan chilensis post. There isn't a lot to add except to note that Powell (2003) also summarizes the various bits known to that time, and that titanosaurs are present in Dorotea Formation beds in southern Chile, equivalent to the Nullotitan-yielding Chorrillo Formation of southernmost Argentina (rather than forcing anyone to chase down conference abstracts, you can find this in Novas et al. 2019).

Peru: "Titanosaurine" bones are reportedly relatively common in the basal redbeds of the Bagua Formation of Peru (Mourier et al. 1988). Mourier et al. (1986) drew attention to a group of four incomplete and relatively small procoelous caudals from the Pongo de Rentema area of northwestern Peru.

Uruguay: Titanosaur remains are not a new thing in Uruguay; von Huene, for example, assigned various remains to better-known genera and species from Argentina (e.g., Huene 1931), but these specimens cannot be assigned to genera or species (Powell 2003). A more promising report was made in Soto et al. (2012), which described a collection of bones catalogued as FC-DVP 1900 from the Guichón Formation of western Uruguay. These bones include 48 caudal centra and fragments of at least nine more; two caudal neural arches; part of a coracoid; a fragmentary ulna; fragments of metacarpals; the proximal end of a right fibula; the distal end of a left tibia; two right astragali; metatarsals; two pedal phalanxes; and five probable discoidal osteoderms. The presence of two right astragali shows that at least two individuals are included in the collection; most of the bones are consistent with an animal about 12 to 14 m long (40 to 46 ft), similar to the anatomically comparable Baurutitan britoi (although the lack of neural arches on the centra indicates a lack of skeletal maturity to me). Eggshells compatible with titanosaurs were also found at this site (Soto et al. 2012). [Update, 2023/03/31: This is now Udelartitan celeste.]

References

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