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New material of Manchurochelys manchoukuoensis (PMOL-AR00180) in ventral view, from the Early Cretaceous Jiufotang Formation of Qilinshan, Chifeng, Inner Mongolia, China. Abbreviations: bo, basioccipital; bs, basisphenoid; cd, central depression of basisphenoid (maybe taphonomic); ce1-7, cervical vertebrae 1-7; d, dentary; ex, exoccipital; fc, fenestra caroticus; fjp, foramen jugulare posterius; h, humerus; hy, hyoid; lar, labial ridge of the triturating surface in maxilla; lir, lingual ridge of the triturating surface in maxilla; m, maxilla; nu, nuchal; op, opisthotic; p1-2, peripheral Plates 1-2; pal, palatine; pt, pterygoid; q, quadrate; s, scapula; sq, squamosal; st, stapes; XII, foramina of cranial nerve XII.
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Manchurochelys manchoukuoensis is an emblematic turtle from the Cretaceous Yixian Formation of Liaoning, China, a geological rock unit that is famous for yielding perfectly preserved skeletons of fossil vertebrates, including that of feathered dinosaurs. Manchurochelys manchoukuoensis was one of the first vertebrates described from this fauna, also...
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Citations
... More recently, Shao et al. (2017) reported a juvenile specimen of M. manchoukuoensis from its type locality, giving the first insight into the ontogeny of this species. Although the aforementioned specimens have provided us with important osteological data on M. manchoukuoensis, several aspects of its anatomy remained unknown, which in turn hindered phylogenetic reconstruction within Sinemydidae as well as understanding character evolution in early branching Pan-Cryptodira (e.g., Zhou 2010a, 2010bZhou et al. 2014;Joyce et al. 2016;Shao et al. 2018). ...
... Using micro-CT scanning of the skull and a rarely applied but promising technique for compressed fossils, X-ray computed laminography scanning of the postcranium, we here contribute a comprehensive description of the osteology of M. manchoukuoensis. The description is supplemented with first-hand data from previously reported specimens (PMOL-AR00008, Zhou Zhou 2010b; PMOL-AR00180, Zhou et al. Zhou et al. 2014; PMOL-AR00007, Shao et al. Shao et al. 2017). ...
... Remarks-The family Sinemydidae was erected by Ye (1963) to include Sinemys lens and Manchurochelys manchoukuoensis. Since then the family has been proposed to include Early Cretaceous turtles from Asia and North America by subsequent workers either based or not based on phylogenetic analysis (e.g., Gaffney 1996;Brinkman and Wu 1999;Brinkman et al. 2008;Zhou 2010aZhou , 2010bZhou et al. 2014;Zhou and Rabi 2015;Joyce et al. 2016;Shao et al. 2018). In brief, there have been two kinds of proposals as to the composition of Sinemydidae: first, the most exclusive application of the name includes only Sinemys spp. ...
Manchurochelys manchoukuoensis is a sinemydid stem-cryptodire turtle known by fossils from the Lower Cretaceous beds exposed in western Liaoning and Inner Mongolia of China. This fossil taxon is important for understanding the origin and evolution of Cryptodira (crown-group hidden-neck turtles). The holotype of M. manchoukuoensis was presumably lost during the Second World War and several aspects of the osteology of the species remains unknown. We here describe a near-complete fossil skeleton coming from the Lower Cretaceous Yixian Formation, western Liaoning, China, 50 km away from the type locality in the same formation. PKUP V1071 represents the most completely preserved specimen of the species and includes a well-preserved plastron, which was otherwise only known partially in the lost holotype. We provide a detailed osteological description of M. manchoukuoensis including data from micro-CT and X-ray computed laminography scanning of PKUP V1071. Of particular significance is the anchor-shaped entoplastron transversely extending to completely separate the small and triangular epiplastra from the hyoplastra; this peculiar morphology is otherwise only present in Sinemys spp. among turtles. Additional novel insights into plastron and cranial anatomy further support a close relationship between Sinemys and Manchurochelys.
... and the Late Cretaceous Borealochelys axelheibergensis, Judithemys sukhanovi, and Judithemys russelli (Brinkman and Tarduno, 2005;Li et al., 2019). The smooth outer surface of the shell, ornamented by numerous irregularly distributed tiny pits and grooves, is shared with the other 'macrobaenids' (Brinkman, 2001;Brinkman and Tarduno, 2005;Zhou, 2010;Zhou et al., 2014). A distinct nuchal notch is absent in Wuguia spp., Anatolemys maximus, Borealochelys axelheibergensis and most representatives of the genus Judithemys. ...
... A very shallow nuchal notch is present in some specimens of Judithemys backmani, and always absent in Judithemys sukhanovi and Osteopygis emarginatus Brinkman and Tarduno, 2005;Danilov and Sukhanov, 2006;Weems, 2014;Brinkman, 2015). An anterior notch is present in Manchurochelys manchoukuoensis, but is very shallow (Zhou et al., 2014). In Liaochelys jianchangensis the anterior notch is slightly deeper, but also weakly developed (Zhou, 2010). ...
... Dracochelys bicuspis differs from Gallica lapparentiana, as well as from the other 'macrobaenids,' in the absence of a cervical scute (Zhou et al., 2014). The identification of a broad cervical that is almost five times wider than long is shared with Osteopygis emarginatus, Judithemys sukhanovi, and Judithemys russelli, but not with Judithemys backmani and Borealochelys axelheibergensis (Brinkman, 2015). ...
The European Paleocene terrestrial and freshwater turtle fauna is radically different from that in the Upper Cretaceous. This Paleocene fauna is largely formed by groups of turtles not found in the Mesozoic record of the continent. However, European Paleocene sites have produced several lineages that dispersed from other continents, including basal turtles (i.e., stem Testudines) and compsemydids (i.e., Paracryptodira). Both groups are well represented at the French upper Paleocene site of Mont de Berru, Marne Department. A new taxon from this locality, Gallica lapparentiana, gen. et sp. nov., is described here and attributed to the eucryptodiran lineage ‘Macrobaenidae.’ Heretofore, no ‘macrobaenid’ has yet been identified in the Cenozoic record of Europe. ‘Macrobaenids’ have their origin in the Upper Jurassic of Asia. In fact, they represent the most diverse group of turtles currently known for the Lower Cretaceous record in that continent. They reach North America in the Upper Cretaceous, where they continue to diversify during the Upper Cretaceous and lower Paleocene. The first justified identification of ‘Macrobaenidae’ from the upper Paleocene of Europe, both in France and in Belgium, provides new data on the replacement process of European Late Cretaceous turtle fauna by new groups from other continents.
http://zoobank.org/urn:lsid:zoobank.org:pub:B417CC80-F47C-4AE5-B8B2-0BAA249A177F
... However, we note that the position of pleurodires has been unstable in many phylogenetic analyses of global turtle datasets (e.g. Sterli, 2010;Zhou, Rabi & Joyce, 2014), and uncertainty regarding the phylogenetic position of pleurodires might explain not only the unexpected sister-group relationship with angolachelonians here, but might also cause the controversy surrounding the relative position of xinjiangchelyids, sinemydids, and macrobaenids as stem-group turtles or stem-group cryptodires (e.g. Zhou, Rabi & Joyce, 2014;Zhou & Rabi, 2015). ...
... Sterli, 2010;Zhou, Rabi & Joyce, 2014), and uncertainty regarding the phylogenetic position of pleurodires might explain not only the unexpected sister-group relationship with angolachelonians here, but might also cause the controversy surrounding the relative position of xinjiangchelyids, sinemydids, and macrobaenids as stem-group turtles or stem-group cryptodires (e.g. Zhou, Rabi & Joyce, 2014;Zhou & Rabi, 2015). Examination of a more complete sample of early stem-and crown-group pleurodires will be important for character polarisations at the base of Pleurodira and resolving the membership of their total group. ...
Knowledge of the early evolution of sea turtles (Chelonioidea) has been limited by conflicting phylogenetic hypotheses resulting from sparse taxon sampling and a superficial understanding of the morphology of key taxa. This limits our understanding of evolutionary adaptation to marine life in turtles, and in amniotes more broadly. One problematic group are the protostegids, Early-Late Cretaceous marine turtles that have been hypothesised to be either stem-cryptodires, stem-chelonioids, or crown-chelonioids. Different phylogenetic hypotheses for protostegids suggest different answers to key questions, including (1) the number of transitions to marine life in turtles, (2) the age of the chelonioid crown-group, and (3) patterns of skeletal evolution during marine adaptation. We present a detailed anatomical study of one of the earliest protostegids, Rhinochelys pulchriceps from the early Late Cretaceous of Europe, using high-resolution μCT. We synonymise all previously named European species and document the variation seen among them. A phylogeny of turtles with increased chelonioid taxon sampling and revised postcranial characters is provided, recovering protostegids as stem-chelonioids. Our results imply a mid Early Cretaceous origin of total-group chelonioids and an early Late Cretaceous age for crown-chelonioids, which may inform molecular clock analyses in future. Specialisations of the chelonioid flipper evolved in a stepwise-fashion, with innovations clustered into pulses at the origin of total-group chelonioids, and subsequently among dermochelyids, crown-cheloniids, and gigantic protostegids from the Late Cretaceous.
... The juveniles are comparable in shell morphology and identified as the same taxon as the adult IVPG-T001-1 by the shell profile, preneural plate, and wider vertebral scales, all which are distinct from the sympatric S. lens (Fig. 2). Comparative anatomical studies were conducted through first hand examination of sinemydid species: Dracochelys bicuspis Gaffney & Ye, 1992 (IVPP V4075 holotype, IVPP V12091;Brinkman, 2001); Kirgizemys (=Hangaiemys) hoburensis (Sukhanov & Narmandakh, 1974) (PIN 3334-4, PIN 3334-1, PIN 3334-5, PIN 3334-16, PIN 3334-34, PIN 3334-35, PIN 3334-36, PIN 3334-37); Judithemys sukhanovi Parham & Hutchison, 2003 (TMP 87.2.1 holotype andmaterial listed in Parham & Hutchison, 2003); Liaochelys jianchangensis Zhou, 2010a (PMOL-AR00140 holotype, PMOL-AR00160); Manchurochelys manchoukuoensis Endo & Shikama, 1942Zhou, 2010b;Zhou, Rabi & Joyce, 2014;Shao et al., 2017); Ordosemys leios Brinkman & Peng, 1993a (IVPP V9534-1 holotype, andmaterial listed in Brinkman & Peng, 1993a); Ordosemys liaoxiensis (Ji, 1995) (IVPP V11554, SDUST-V1020, and material listed in Tong, Ji & Ji, 2004 (Khosatzky, 1996) ((Danilov & Sukhanov, 2006); Asiachelys perforata Sukhanov & Narmandakh, 2006(Ordosemys perforata sensu Danilov & Parham, 2007; Manchurochelys donghai (Ma, 1986) (Ordosemys donghai sensu Brinkman, Li & Ye, 2008. See also Sukhanov (2000), Rabi, Joyce & Wings (2010), and Danilov, Syromyatnikova & Sukhanov (2017 for reviews on Mesozoic turtles from Asia. ...
Chronostratigraphic correlation of terrestrial Early Cretaceous biotas in China is highly problematic due to the lack of marine deposits, few absolute dates, and limited number of index fossils. This often leaves vertebrate faunas as one of the few potential tools for a preliminary biostratigraphy. Taxonomic identity of fragmentary fossils is, however, often uncertain and many faunas are insufficiently sampled. Turtles are one of the most common elements of Early Cretaceous biotas of Asia and their skeleton is frequently preserved more completely than that of other vertebrates- they yet receive little attention from vertebrate paleontologists. We here record the presence of the sinemydid turtle Ordosemys leios from the Lower Cretaceous Mengyin Formation of Shandong Province, China, best known for the first dinosaurs and Mesozoic turtles described from the country. Ordosemys is the third turtle reported from the Mengyin Formation along with Sinemys lens and Sinochelys applanata and the only other formation where Ordosemys is known to co-occur with Sinemys is the Luohandong Formation of the Ordos Basin (Inner Mongolia), the type and so far only horizon of Ordosemys leios . The presence of the crocodyliform Shantungosuchus may further define a fauna that is so far only known from these two formations. The stratigraphic position of the Luohandong Formation is poorly controlled and it has been placed anywhere between the Valanginian and Aptian. Published absolute dates from the Mengyin Formation and the numerous shared vertebrate and invertebrate taxa (now also including turtles) implies a Valanginian—early Hauterivian age for the Luohandong Formation—in contrast to late Hauterivian-Albian as previously proposed using the temporal distribution of Psittacosaurus . The new specimen of Ordosemys leios preserves the only known manus of this species and ecomorphological analysis of limb proportions implies that it was a less capable swimmer compared to Ordosemys liaoxiensis coming from the younger Jehol Biota.
... Only a few shells of a basal trionychoid, Sinaspideretes wimani, have been recorded from the Late Jurassic Shangshaximiao Formation in the Sichuan Basin (Tong et al. 2014). In addition, the turtle assemblage from Phu Noi is distinct from those from the Early Cretaceous of inland Asia (Central Asia and China) which are generally composed of more advanced eucryptodiran Sinemydidae/Macrobaenidae (Brinkman & Peng, 1993a, b;Sukhanov, 2000;Tong et al. 2004;Danilov, 2006;Danilov & Parham, 2007;Zhou, 2010a, b;Brinkman et al. 2013a;Zhou et al. 2014;Zhou & Rabi, 2015). Danilov & Parham (2007) have assigned the holotype of 'Sinemys' wuerhoensis Ye, 1973 from the Early Cretaceous of the Tugulu Group, Xinjiang, China, to Xinjiangchelyidae. ...
A new xinjiangchelyid turtle, Kalasinemys prasarttongosothi n. gen. n. sp., is described on the basis of skull and shell material from the Upper Jurassic Phu Kradung Formation at Phu Noi locality, Kalasin Province, in NE Thailand. This second xinjiangchelyid turtle from Phu Noi is distinct from Phunoichelys thirakhupti by the smooth shell surface, the presence of a cervical notch, and vertebral 1 narrower than nuchal. The skull presents an arterial system characteristic of the Xinjiangchelyidae (basal Eucryptodira), and its outline is similar to that of Annemys spp. known from the Middle–Late Jurassic of China and Mongolia, but distinct from the latter mainly by the wider triturating surface, smaller foramen palatinum posterius and the shape of the prefrontal and frontal, as well as that of the basisphenoid and basioccipital. Based on the turtle assemblages, the correlation with mainland Asia further supports a Late Jurassic age for the lower part of the Phu Kradung Formation where Phu Noi site is located stratigraphically. Our study provides new insight on the evolution of the basal eucryptodiran turtles in Asia.
... A phylogenetic analysis was performed herein to explore if the new insights gained into the anatomy of D. lowii have an impact on its phylogenetic placement. For this purpose, the global character/taxon matrix of Cadena & Parham (2015) was utilized, which in return is a combination of previously published matrices of marine turtle relationships (Hirayama, 1994(Hirayama, , 1998Kear & Lee, 2006;Parham & Pyenson, 2010;Bardet et al., 2013;Lapparent De Broin et al., 2014) and global turtle phylogenies (Joyce, 2007;Sterli, 2008;Joyce et al., 2011;Anquetin, 2012;Rabi et al., 2013;Sterli & De la Fuente, 2013;Zhou, Rabi & Joyce, 2014). The matrix was adjusted using the following modification. ...
Background: The phylogenetic placement of Cretaceous marine turtles, especially Protostegidae, is still under debate among paleontologists. Whereas protostegidswere traditionally thought to be situated within the clade of recent marine turtles (Chelonioidea), some recent morphological and molecular studies suggest placementalong the stem of Cryptodira. The main reason why the evolution of marine turtles is still poorly understood, is in part due to a lack of insights into the cranialanatomy of protostegids. However, a general availability of high-quality fossil material, combined with modern analysis techniques, such as X-ray microtomography, provide ample opportunity to improve this situation. The scopeof this study is to help resolve its phylogenetic relationships by providing a detailed description of the external and internal cranial morphology of the extinctprotostegid sea turtle Desmatochelys lowii Williston, 1894.Material and Methods: This study is based on the well-preserved holotype of Desmatochelys lowii from the Late Cretaceous (middle Cenomanian to early Turonian) Greenhorn Limestone of Jefferson County, Nebraska. The skulls of two recent marine turtles, Eretmochelys imbricata (Linnaeus, 1766) (Cheloniidae) and Dermochelys coriacea Lydekker, 1889 (Dermochelyidae), as well as the snapping turtle Chelydra serpentina (Linnaeus, 1758) (Chelydridae) provide a comparative basis. All skulls were scanned using regular or micro CT scanners and the scans were then processed with the software program Amira tocreate 3D isosurface models. In total, 81 bones are virtually isolated, figured, and described, including the nature of their contacts. The novel bone contact data is compiled and utilized in a preliminary phenetic study. In addition, anupdate phylogenetic analysis is conduced that utilizes newly obtained anatomical insights.Results: The detailed examination of the morphology of the herein used specimens allowed to explore some features of the skull, to refine the scoring of Desmatochelyslowii in the recent global matrix of turtles, and develop five new characters. The alleged pineal foramen in the type skull of Desmatochelys lowii is shown to bethe result of damage. Instead, it appears that the pineal gland only approached the skull surface, as it is in Dermochelys coriacea. Whereas the parasphenoid inconfirmed to be absent in hard-shelled sea turtles, ist possible presence in Desmatochelys lowii is unclear. The results of the phenetic study show that Desmatochelys lowii is least similar to the other examined taxa in regards to the nature of its bone contacts, and therefore suggests a placement outside Americhelydia for this protostegid sea turtle. The phylogenetic study results in a placement of Protostegidae along the stem of Chelonioidea, which is a novel position for the group.
... A phylogenetic analysis was performed herein to explore if the new insights gained into the anatomy of D. lowii have an impact on its phylogenetic placement. For this purpose, the global character/taxon matrix of Cadena & Parham (2015) was utilized, which in return is a combination of previously published matrices of marine turtle relationships (Hirayama, 1994(Hirayama, , 1998Kear & Lee, 2006;Parham & Pyenson, 2010;Bardet et al., 2013;Lapparent De Broin et al., 2014) and global turtle phylogenies (Joyce, 2007;Sterli, 2008;Joyce et al., 2011;Anquetin, 2012;Rabi et al., 2013;Sterli & De la Fuente, 2013;Zhou, Rabi & Joyce, 2014). The matrix was adjusted using the following modification. ...
Background
The phylogenetic placement of Cretaceous marine turtles, especially Protostegidae, is still under debate among paleontologists. Whereas protostegids were traditionally thought to be situated within the clade of recent marine turtles (Chelonioidea), some recent morphological and molecular studies suggest placement along the stem of Cryptodira. The main reason why the evolution of marine turtles is still poorly understood, is in part due to a lack of insights into the cranial anatomy of protostegids. However, a general availability of high-quality fossil material, combined with modern analysis techniques, such as X-ray microtomography, provide ample opportunity to improve this situation. The scope of this study is to help resolve its phylogenetic relationships by providing a detailed description of the external and internal cranial morphology of the extinct protostegid sea turtle Desmatochelys lowii Williston, 1894.
Material and Methods
This study is based on the well-preserved holotype of Desmatochelys lowii from the Late Cretaceous (middle Cenomanian to early Turonian) Greenhorn Limestone of Jefferson County, Nebraska. The skulls of two recent marine turtles, Eretmochelys imbricata (Linnaeus, 1766) (Cheloniidae) and Dermochelys coriacea Lydekker, 1889 (Dermochelyidae), as well as the snapping turtle Chelydra serpentina (Linnaeus, 1758) (Chelydridae) provide a comparative basis. All skulls were scanned using regular or micro CT scanners and the scans were then processed with the software program Amira to create 3D isosurface models. In total, 81 bones are virtually isolated, figured, and described, including the nature of their contacts. The novel bone contact data is compiled and utilized in a preliminary phenetic study. In addition, an update phylogenetic analysis is conduced that utilizes newly obtained anatomical insights.
Results
The detailed examination of the morphology of the herein used specimens allowed to explore some features of the skull, to refine the scoring of Desmatochelys lowii in the recent global matrix of turtles, and develop five new characters. The alleged pineal foramen in the type skull of Desmatochelys lowii is shown to be the result of damage. Instead, it appears that the pineal gland only approached the skull surface, as it is in Dermochelys coriacea. Whereas the parasphenoid in confirmed to be absent in hard-shelled sea turtles, ist possible presence in Desmatochelys lowii is unclear. The results of the phenetic study show that Desmatochelys lowii is least similar to the other examined taxa in regards to the nature of its bone contacts, and therefore suggests a placement outside Americhelydia for this protostegid sea turtle. The phylogenetic study results in a placement of Protostegidae along the stem of Chelonioidea, which is a novel position for the group.
... A new phylogenetic analysis is performed with TNT v1.5 beta (Goloboff & Catalano, 2016) based on the latest dataset of global turtle phylogeny (Joyce et al., 2016), which was updated from previous analyses (Joyce, 2007;Zhou, Rabi & Joyce, 2014;Zhou & Rabi, 2015). We used the traditional search option and tree-bisection-reconnection swapping algorithm with 1,000 random addition sequence replicates and 100 trees saved per replicate. ...
Hyperphalangy is a rare condition in extant aquatic turtles, and mainly limited to soft-shelled turtles. Here we report a new freshwater turtle, Jeholochelys lingyuanensis gen. et sp. nov. from the Early Cretaceous Jehol Biota of western Liaoning, China. This new turtle is characterized by a hyperphalangy condition with one additional phalanx in pedal digit V, rather than the primitive condition (phalangeal formula: 2-3-3-3-3) of crown turtles. J. lingyuanensis is recovered with other coexisting turtles in the family Sinemydidae in the phylogenetic analysis. This discovery further confirms that hyperphalangy occurred multiple times in the early evolutionary history of the crown turtles. Hyperphalangy is possibly a homoplasy in Jeholochelys and the soft-shelled turtles to adapt to the aquatic environments.
... A new phylogenetic analysis is performed with TNT v1.5 beta (Goloboff & Catalano, 2016) based on the latest dataset of global turtle phylogeny (Joyce et al., 2016), which was updated from previous analyses (Joyce, 2007;Zhou, Rabi & Joyce, 2014;Zhou & Rabi, 2015). We used the traditional search option and tree-bisection-reconnection swapping algorithm with 1,000 random addition sequence replicates and 100 trees saved per replicate. ...
Hyperphalangy is a rare condition in extant aquatic turtles, and mainly limited to soft-shelled turtles. Here we report a new freshwater turtle, Jeholochelys lingyuanensis gen. et sp. nov. from the Early Cretaceous Jehol Biota of western Liaoning, China. This new turtle is characterized by a hyperphalangy condition with one additional phalanx in pedal digit V, rather than the primitive condition (phalangeal formula: 2-3-3-3-3) of crown turtles. J. lingyuanensis is recovered with other coexisting turtles in the family Sinemydidae in the phylogenetic analysis. This discovery further confirms that hyperphalangy occurred multiple times in the early evolutionary history of the crown turtles. Hyperphalangy is possibly a homoplasy in Jeholochelys and the soft-shelled turtles to adapt to the aquatic environments.
... Joyce (2007) included an expanded sample by scoring Plesiochelys etalloni, Portlandemys mcdowelli, Jurassichelon oleronensis (his "Thalassemys" moseri), and Solnhofia parsonsi as terminal taxa, but they were found in a paraphyletic arrangement. More recent global phylogenetic analyses of turtles continued to include these species as separate terminal taxa Parham 2006, 2008;Sterli 2010;Anquetin 2012;Rabi et al. 2013;Sterli et al. 2013;Zhou et al. 2014;Zhou and Rabi 2015), but none found them to form a monophyletic group. ...
The Late Jurassic (Oxfordian to Tithonian) fossil record of Europe and South America has yielded a particularly rich assemblage of aquatic pan-cryptodiran turtles that are herein tentatively hypothesized to form a monophyletic group named Thalassochelydia. Thalassochelydians were traditionally referred to three families, Eurysternidae, Plesiochelyidae, and Thalassemydidae, but the current understanding of phylogenetic relationships is insufficient to support the monophyly of either group. Given their pervasive usage in the literature, however, these three names are herein retained informally. Relationships with marine turtles from the Cretaceous have been suggested in the past, but these hypotheses still lack strong character support. Thalassochelydians are universally found in near-shore marine sediments and show adaptations to aquatic habitats, but isotopic evidence hints at a broad spectrum of specializations ranging from freshwater aquatic to fully marine. A taxonomic review of the group concludes that of 68 named taxa, 27 are nomina valida, 18 are nomina invalida, 18 are nomina dubia, and 5 nomina oblita.
