Knoetschkesuchus: Difference between revisions
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[[File:Knoetschke-11.png|thumb|''Knoetschkesuchus langenbergensis'' compared with ''Theriosuchus pusillus'']] |
[[File:Knoetschke-11.png|thumb|''Knoetschkesuchus langenbergensis'' compared with ''Theriosuchus pusillus'']] |
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When the known specimens of ''K. langenbergensis'' were first described in a preliminary fashion by a 2006 paper from Hans-Volker Karl and colleagues, they were referred to the genus ''Theriosuchus''. This was on the basis of the short skull, divided nostrils, large eye sockets compared to the supratemporal fenestrae, and the bevelled side of the squamosal. Specifically, they recognized its similarity to ''T. pusillus'' on the basis of its osteoderms and teeth, although they noted that the orientation of the back of the skull was different and that leaf-shaped teeth were absent. These differences were attributed to ''K. langenbergensis'' probably representing a different life stage of ''T. pusillus'' compared to the type specimen.<ref name="tennant2016"/> A 2016 analysis of the relationships of the Atoposauridae, from Jonathan Tennant and colleagues, tentatively supported the affinity of these specimens with ''T. pusillus'' on account of the teeth being situated in a groove (a trait uniting ''T. pusillus'' and ''"T." guimarotae'' in their analysis), the presence of pseudocaniniform teeth, and the lance head-shaped teeth near the back of the jaw. However, they noted that the nasals essentially completely divide the nostrils to the exclusion of other bones, which is not seen in the genus of ''Theriosuchus''.<ref name="tennant2016">{{cite journal | last1 = Tennant | first1 = J.P. | last2 = Mannion | first2 = P.D. | last3 = Upchurch | first3 = P. | title = Evolutionary relationships and systematics of Atoposauridae (Crocodylomorpha: Neosuchia): implications for the rise of Eusuchia | journal = Zoological Journal of the Linnaean Society | volume = 177 | issue = 4 | date = 2016 | pages = 854–936 | doi = 10.1111/zoj.12400 | url = http://onlinelibrary.wiley.com/doi/10.1111/zoj.12400/full}}</ref> |
When the known specimens of ''K. langenbergensis'' were first described in a preliminary fashion by a 2006 paper from Hans-Volker Karl and colleagues, they were referred to the genus ''Theriosuchus''. This was on the basis of the short skull, divided nostrils, large eye sockets compared to the supratemporal fenestrae, and the bevelled side of the squamosal. Specifically, they recognized its similarity to ''T. pusillus'' on the basis of its osteoderms and teeth, although they noted that the orientation of the back of the skull was different and that leaf-shaped teeth were absent. These differences were attributed to ''K. langenbergensis'' probably representing a different life stage of ''T. pusillus'' compared to the type specimen.<ref name="karl2006">{{cite journal | last1 = Karl | first1 = H.-V. | last2 = Gröning | first2 = E. | last3 = Brauckmann | first3 = C. | last4 = Schwarz | first4 = D. | last5 = Knötschke | first5 = N. | title = The Late Jurassic crocodiles of the Langenberg near Oker, Lower Saxony (Germany), and description of related materials (with remarks on the history of quarrying the "Langenberg Limestone" and "Obernkirchen Sandstone") | journal = Clausthaler Geowissenschaften | volume = 5 | date = 2006 | pages = 59-77 | url = https://www.researchgate.net/publication/40663177_The_Late_Jurassic_crocodiles_of_the_Langenberg_near_Oker_Lower_Saxony_Germany_and_description_of_related_materials_with_remarks_on_the_history_of_quarrying_the_Langenberg_Limestone_and_Obernkirchen_Sa}}</ref><ref name="tennant2016"/> A 2016 analysis of the relationships of the Atoposauridae, from Jonathan Tennant and colleagues, tentatively supported the affinity of these specimens with ''T. pusillus'' on account of the teeth being situated in a groove (a trait uniting ''T. pusillus'' and ''"T." guimarotae'' in their analysis), the presence of pseudocaniniform teeth, and the lance head-shaped teeth near the back of the jaw. However, they noted that the nasals essentially completely divide the nostrils to the exclusion of other bones, which is not seen in the genus of ''Theriosuchus''.<ref name="tennant2016">{{cite journal | last1 = Tennant | first1 = J.P. | last2 = Mannion | first2 = P.D. | last3 = Upchurch | first3 = P. | title = Evolutionary relationships and systematics of Atoposauridae (Crocodylomorpha: Neosuchia): implications for the rise of Eusuchia | journal = Zoological Journal of the Linnaean Society | volume = 177 | issue = 4 | date = 2016 | pages = 854–936 | doi = 10.1111/zoj.12400 | url = http://onlinelibrary.wiley.com/doi/10.1111/zoj.12400/full}}</ref> |
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However, the taxonomy of ''Theriosuchus'' itself is somewhat convoluted. Most studies have not provided a defined set of characteristics that unite species of ''Theriosuchus'' and separate them from other atoposaurids; the only such diagnoses that have explicitly been given were provided by Steve Salisbury and [[Darren Naish]] in 2011, and Jeremy Martin and colleagues in 2010. In 2016 Mark Young and colleagues criticized these diagnoses, noting that many characters were either more widely distributed among the Atoposauridae, difficult to assess, or - in the case of the latter diagnosis - not present at all. Young ''et al.'' provided an alternative diagnosis containing nine traits, mostly involving teeth; however, they also noted that there was variation among the expression of these traits, which calls into question the [[monophyly]] of ''Theriosuchus''. ''K. langenbergensis'' differs from this diagnosis in four out of nine traits, which Schwarz ''et al.'' cited as a basis for both the generic separation of ''Knoetschkesuchus'' and the necessity of revising the diagnosis further.<ref name="desc"/> |
However, the taxonomy of ''Theriosuchus'' itself is somewhat convoluted. Most studies have not provided a defined set of characteristics that unite species of ''Theriosuchus'' and separate them from other atoposaurids; the only such diagnoses that have explicitly been given were provided by Steve Salisbury and [[Darren Naish]] in 2011, and Jeremy Martin and colleagues in 2010.<ref name="martin2010">{{cite journal | last1 = Martin | first1 = J.E. | last2 = Rabi | first2 = M. | last3 = Cziki | first3 = Z. | title = Survival of ''Theriosuchus'' (Mesoeucrocodylia: Atoposauridae) in a Late Cretaceous archipelago: a new species from the Maastrichtian of Romania | journal = Naturwissenschaften | volume = 97 | issue = 9 | pages = 845-854 | date = 2010 | doi = 10.1007/s00114-010-0702-y | url = https://link.springer.com/article/10.1007%2Fs00114-010-0702-y}}</ref> In 2016 Mark Young and colleagues criticized these diagnoses, noting that many characters were either more widely distributed among the Atoposauridae, difficult to assess, or - in the case of the latter diagnosis - not present at all. Young ''et al.'' provided an alternative diagnosis containing nine traits, mostly involving teeth; however, they also noted that there was variation among the expression of these traits, which calls into question the [[monophyly]] of ''Theriosuchus''.<ref name="young2016">{{cite journal | last1 = Young | first1 = M.T. | last2 = Tennant | first2 = J.P. | last3 = Brusatte | first3 = S.L. | last4 = Challands | first4 = T.J. | last5 = Fraser | first5 = N.C. | last6 = Clark | first6 = N.D.L. | last7 = Ross | first7 = D.A. | title = The first definitive Middle Jurassic atoposaurid (Crocodylomorpha, Neosuchia), and a discussion on the genus ''Theriosuchus'' | journal = Zoological Journal of the Linnaean Society | volume = 176 | issue = 2 | date = 2016 | pages = 443-462 | doi = 10.1111/zoj.12315 | url = http://onlinelibrary.wiley.com/doi/10.1111/zoj.12315/full}}</ref> ''K. langenbergensis'' differs from this diagnosis in four out of nine traits, which Schwarz ''et al.'' cited as a basis for both the generic separation of ''Knoetschkesuchus'' and the necessity of revising the diagnosis further.<ref name="desc"/> |
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[[File:Knoetschke-10.png|thumb|''Knoetschkesuchus langenbergensis'' compared with ''Knoetschkesuchus guimarotae'']] |
[[File:Knoetschke-10.png|thumb|''Knoetschkesuchus langenbergensis'' compared with ''Knoetschkesuchus guimarotae'']] |
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According to Schwarz ''et al.'', seven traits unite ''K. langenbergensis'' and ''K. guimarotae'', and separate them from other species referred to ''Theriosuchus''. These include the presence of two unique tooth morphotypes; the choanae being placed in shallow grooves rather than a bowl-like depression; the relatively wide top of the skull; the presence of antorbital and mandibular fenestrae in all life stages; and the relatively limited contact between the lacrimal and nasal. Additionally, ''K. langenbergensis'' differs from other species in lacking leaf-shaped or "pseudoserrated" teeth; lacking teeth with low crowns; having a longer maxillary symphysis; having a crest on the side of the downward-projecting process of the postorbital; having overlap between the postorbital and the front of the squamosal; and a rectangular parietal that does not form part of the supratemporal fenestra.<ref name="desc"/> |
According to Schwarz ''et al.'', seven traits unite ''K. langenbergensis'' and ''K. guimarotae'', and separate them from other species referred to ''Theriosuchus''. These include the presence of only two unique tooth morphotypes; the choanae being placed in shallow grooves rather than a bowl-like depression; the relatively wide top of the skull; the presence of antorbital and mandibular fenestrae in all life stages; and the relatively limited contact between the lacrimal and nasal. Additionally, ''K. langenbergensis'' differs from other species in lacking leaf-shaped or "pseudoserrated" teeth; lacking teeth with low crowns; having a longer maxillary symphysis; having a crest on the side of the downward-projecting process of the postorbital; having overlap between the postorbital and the front of the squamosal; and a rectangular parietal that does not form part of the supratemporal fenestra.<ref name="desc"/> |
||
In the 2017 description of ''K. langenbergensis'', Schwartz ''et al.'' used the 2015 [[phylogenetics|phylogenetic]] dataset of Alan Turner, which was revised to remove irrelevant characteristics, add ''K. langenbergensis'' and ''T. grandinaris'', and correct flaws in the coded traits of ''K. guimarotae'' (due to low-resolution images, inaccuracies in the original reconstruction, and the acquirement of new data). The phylogenetic trees recovered by this analysis consistently found that Atoposauridae, represented by ''Knoetschkesuchus'', ''Theriosuchus'', and ''Alligatorium'', forms a monophyletic clade. Within this clade, a close relationship between ''K. langenbergensis'' and ''K. guimarotae'', excluding other ''Theriosuchus'' species, was strongly supported, providing further evidence of these two species forming a separate genus. In some trees, ''T. grandinaris'' was also close to ''Knoetschkesuchus''. The [[maximum parsimony (phylogenetics)|most parsimonious]] arrangement is reproduced below.<ref name="desc"/> |
In the 2017 description of ''K. langenbergensis'', Schwartz ''et al.'' used the 2015 [[phylogenetics|phylogenetic]] dataset of Alan Turner,<ref name="turner2015">{{cite journal | last1 = Turner | first1 = A.H. | title = A Review of ''Shamosuchus'' and ''Paralligator'' (Crocodyliformes, Neosuchia) from the Cretaceous of Asia | journal = PLoS ONE | volume = 10 | issue = 2 | page = e0118116 | date = 2015 | doi = 10.1371/journal.pone.0118116 | url = http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0118116}}</ref> which was revised to remove irrelevant characteristics, add ''K. langenbergensis'' and ''T. grandinaris'', and correct flaws in the coded traits of ''K. guimarotae'' (due to low-resolution images, inaccuracies in the original reconstruction, and the acquirement of new data). The phylogenetic trees recovered by this analysis consistently found that Atoposauridae, represented by ''Knoetschkesuchus'', ''Theriosuchus'', and ''Alligatorium'', forms a monophyletic clade. Within this clade, a close relationship between ''K. langenbergensis'' and ''K. guimarotae'', excluding other ''Theriosuchus'' species, was strongly supported, providing further evidence of these two species forming a separate genus. In some trees, ''T. grandinaris'' was also close to ''Knoetschkesuchus''. The [[maximum parsimony (phylogenetics)|most parsimonious]] arrangement is reproduced below.<ref name="desc"/> |
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Revision as of 17:54, 16 March 2017
| Knoetschkesuchus Temporal range: Kimmeridgian
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| Type specimen of Knoetschkesuchus langenbergensis | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Archosauria |
| Clade: | Pseudosuchia |
| Clade: | Crocodylomorpha |
| Clade: | Crocodyliformes |
| Family: | †Atoposauridae |
| Genus: | †Knoetschkesuchus Schwartz et al., 2017 |
| Type species | |
| Knoetschkesuchus langenbergensis Schwartz et al., 2017
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| Species | |
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Knoetschkesuchus is a genus of small atoposaurid eusuchian from the Late Jurassic of Germany and Portugal. Two species are known: the German species K. langenbergensis, described by Schwartz et al. in 2017 based on two partial skeletons and various isolated bones; and the Portuguese species K. guimarotae, named from three partial skulls as well as various other elements, and originally classified as a species of Theriosuchus. Specimens attributed to K. langenbergensis have also been referred to Theriosuchus pusillus by some researchers.
Description
As with other members of the Atoposauridae, Knoetschkesuchus was very small, measuring less than 1 metre (3 ft 3 in) in length.[1][2]
Snout
The skull of Knoetschesuchus was relatively short, with the snout taking up 47% of skull length in K. langenbergensis and 42% in K. guimarotae.[2] Along the side of the snout are two undulations, a smaller one on the premaxilla and a larger and broader one on the maxilla. The jagged suture between the premaxilla and maxilla is angled towards the front of the skull in K. langenbergensis and towards the back in K. guimarotae.[2] Along the midline of the snout are the thin and wedge-like nasals; the nostrils, which face upwards, are clearly separated by the nasals in K. guimarotae,[2] but it is not clear that this is the case in K. langenbergensis.[1]
At the back, the nasals are separated by the frontal in K. langenbergensis, the back third of which is somewhat vaulted. The portion of the frontal between the eyes is one-third the width of the entire skull in both species, but it widens further back to form the front of the skull roof. The prefrontal is straight along its contact with the frontal and nasal (about half of the bone is in contact with each), but forms an angle between the margin of the eye socket and the lacrimal on the other side. This angle is rounded in K. guimarotae such that the bone is oval-shaped,[2] but very pointed in K. langenbergensis such that the bone is triangular.[1]
Eye socket and skull roof
The main body of the lacrimal is a rounded square with both faces of the bone are concave. Its contact with the nasal is rather limited in both species. The oval-shaped antorbital fenestra is quite small, being only 9% the length of the eye socket; its presence is unique to both species of the genus among atoposaurids. Meanwhile, the eye socket is large and oval, being 54% longer than it is tall. The drop-shaped palpebrals project out from the tops of the eye sockets. In both species, the back two-thirds of the inner surface of the palpebral is slightly concave. Both species have a squamosal in which the back third is bevelled; in K. langenbergensis, the outer margin is somewhat convex.[1]
Viewed from the top, the parietal increases in width at the back; the increase is small in K. langenbergensis, such that the bone is overall rectangular, but the difference is larger in K. guimarotae. The back of the bone bears a small notch in K. langenbergensis and a general concavity in K. guimarotae that slightly exposes the underlying supraoccipital.[2] The postorbital bears two branches that join with a gentle curve, separated by an angle of 130° in K. langenbergensis. The supratemporal fenestra is roughly square in K. guimarotae[2] but has a thinner back end in K. langenbergensis. In both species, the maximum distance between the supratemporal fenestrae is about a third of the total width of the top of the skull. The trapezoidal infratemporal fenestra is 1.5 times as long as it is wide in K. langenbergensis.[1]
Palate and braincase
On the bottom of the skull, the pterygoid is about twice as wide as it is long. At the front of the pterygoid is a small projection that extends backwards to form a ridge, on either side of which is a furrow-like depression (the choanal groove) containing the choanae. In Theriosuchus, the choanae are embedded in a wider bowl-like depression. Additionally, in both species, the bottom surface of the pterygoid is somewhat concave. Extending forward from either side of the pterygoid is the ectopterygoid; in both species, this bone is constricted near the middle to form an hourglass-like shape, but in K. langenbergensis it is also somewhat twisted to the side. The back of the bone is very concave in both species.[1][2]
Forming the sides of the back of the skull is the exoccipital, which surrounds most of the foramen magnum. The Eustachian tube extends downwards across the basoccipital and basisphenoid; these bones are thickened on either side of the tube in K. langenbergensis. K. guimarotae has a small rounded foramen beside the tube on the basoccipital, and a tuberosity bearing a ridge above.[2] On the front of the basoccipital in both species, there are two rounded depressions near the bottom. The basisphenoidresembles a triangular hatchet in shape when viewed from the side.[1]
Jaw
In K. guimarotae, the two halves of the dentary diverge from each other at an angle of 20° near the front, then 40° near the back.[2] It also bears two convexities on the jaw, one at the third and fourth teeth and another at the eighth to tenth teeth. The latter convexity is replaced by a concavity in K. langenbergensis. In both species, the top margin of the jaw behind the tooth row slopes upwards in a straight line. The side of the dentary is pitted, albeit much more densely so in K. langenbergensis. Near the back of the dentary in both species, the pits are replaced by longitudinal grooves. On the interior of the jaw, the splenial bears an oval foramen behind the level of the symphysis in both species, and the top of the bone bears a low and roughened crest in K. guimarotae.[1][2]
The tip of the angular is situated close to the midpoint of the bone in K. langenbergensis rather than being at the back as in K. guimarotae.[2] In both species, the back of the angular contributes to the retroarticular process. The inner surface of the angular is roughened in K. guimarotae, and the top margin of the inner walltransitions from an upward-projecting tip at the front to a low, rounded crest at the back;[2] the same margin maintains its height along the angular in K. langenbergensis. The surangular bears a thin, forward-projecting process that, in K. langenbergensis, extends forward to the back of the tooth row and bears a groove on the bottom.[2] The presence of the oval-shaped[2] external mandibular fenestra is unique to the genus among atoposaurids.[1]
Teeth
Both species of Knoetschkesuchus have two distinct types of teeth, uniquely among atoposaurids. The first type of teeth, found near the front of the jaw, are conical, slightly constricted at the base, and curved slightly inwards.[2] The pseudocaniniform teeth, which are the fourth and fifth maxillary teeth, are enlarged (about twice the size of the other maxillary teeth), more pointed, and more constricted at the base. The second type of teeth, which constitutes the rest of the teeth, are shaped like thin lance heads, with a wide base and a narrower tip; in K. guimarotae all of the tips are sharp,[2] but in K. langenbergensis they gradually become blunter.[1]
There are 5 premaxillary teeth in both species,[2] the fourth of which is about a third larger relative to the others. The maxilla has 12 distinct sockets in K. langenbergensis. Excluding the pseudocaniniforms, the maxillary tooth size remains roughly constant but gradually decreases after the pseudocaniniforms in both species; all tooth sockets after the twelfth are replaced by a continuous trough. In total, K. guimarotae had at least 15 maxillary teeth,[2] and K. langenbergensis 17 or 18. Meanwhile, the dentary exhibits 21 teeth in K. langenbergensis and at least 20 in K. guimarotae.[2] Like the maxilla, distinct sockets for dentary teeth are replaced by a groove from the eleventh tooth backwards in K. langenbergensis.[1]
Discovery and naming
K. langenbergensis
The material of the type species of Knoetschkesuchus, K. langenbergensis, comes from a marly limestone bed (numbered as Bed 83, not Bed 93 as reported by some publications) containing recrystallized micritic intraclasts, located within the Langenberg Quarry in the Harz Mountains near Goslar, Lower Saxony, Germany. These deposits have been dated to the Upper Kimmeridgian stage of the Jurassic - specifically, to the regional equivalent of the Upper Kimmeridgian known as the Mittleres Kimmeridge, and belong to the Süntel Formation. Although well-preserved, fossils from this quarry were recovered generally by regular blasting operations in the quarry.[1]
Specimens belonging to Knoetschkesuchus are stored at the Dinosaurier-Freilichtmuseum Münchehagen (hereafter denoted by DFMMh/FV) in Rehburg-Loccum, Germany. They are: the type specimen DFMMh/FV 200, the partial skeleton of an adult with a skull; DFMMh/FV 605, the complete skull of a juvenile; DFMMh/FV 261, an isolated angular; DFMMh/FV 790.12, an isolated left dentary; DFMMh/FV 279, an isolated femur; DFMMh/FV 790.11, an isolated metatarsal; and DFMMh/FV 325, a partial skeleton including osteoderms, vertebrae, and ribs. Stereomicroscopy was used to examine the specimens, which were described in a 2017 paper published by Daniela Schwarz, Maik Raddatz, and Oliver Wings.[1]
The genus name Knoetschkesuchus combines the family name of Nils Knötschke, a researcher at the DFMMh who was responsible for the collection, curation, and preparation of Langenberg Quarry specimens, with the common crocodilian suffix suchus, from the Greek souchos ("crocodile"). Meanwhile, the species name langenbergensis is in reference to the provenance of this species from the Langenberg Quarry.[1]
K. guimarotae
Schwarz and colleagues also assigned an additional species to Knoetschkesuchus, K. guimarotae, which was originally classified as a species of Theriosuchus.[1] As reflected by the specific name, K. guimarotae originates from the lignite layers of the Guimarota quarry, located near Leiria, Portugal. There are two primary vertebrate-bearing lignite strata within the so-called Guimarota-strata, which are separated by marly limestone and respectively known as the Fundschichten and Ruafolge subunits; K. guimarotae is known from both of these layers. have been assigned to the Alcobaça Formation, a subunit of the Abadia Formation, which has also been assigned to the Kimmeridgian on the basis of fossil ostracods.[2]
The remains of K. guimarotae are stored at the Institute of Geological Sciences of the Free University of Berlin (hereafter IPFUB). Alongside the type specimen IPFUB Gui Croc 7308 - which consists of a partial skull with jaws, a vertebra from the sacrum, and two osteoderms - over 400 additional specimens are known, most of them consisting of single isolated bones. Among these, the more complete specimens are IPFUB Gui Gui Croc 7352 (tail vertebrae, femur, osteoderms); 7441 (osteoderms and ulna); 7545 (dorsal vertebrae, ischia, osteoderms); 7564 (femur, humerus, osteoderms); 7634 (dorsal vertebrae, rib, osteoderms); and 8037 (cervical and dorsal vertebrae, and osteoderms). More specimens are known, but they remain unprepared. Some specimens show the marks of scavenging.[2]
Classification
 | This section needs additional citations for verification. (March 2017) |
When the known specimens of K. langenbergensis were first described in a preliminary fashion by a 2006 paper from Hans-Volker Karl and colleagues, they were referred to the genus Theriosuchus. This was on the basis of the short skull, divided nostrils, large eye sockets compared to the supratemporal fenestrae, and the bevelled side of the squamosal. Specifically, they recognized its similarity to T. pusillus on the basis of its osteoderms and teeth, although they noted that the orientation of the back of the skull was different and that leaf-shaped teeth were absent. These differences were attributed to K. langenbergensis probably representing a different life stage of T. pusillus compared to the type specimen.[3][4] A 2016 analysis of the relationships of the Atoposauridae, from Jonathan Tennant and colleagues, tentatively supported the affinity of these specimens with T. pusillus on account of the teeth being situated in a groove (a trait uniting T. pusillus and "T." guimarotae in their analysis), the presence of pseudocaniniform teeth, and the lance head-shaped teeth near the back of the jaw. However, they noted that the nasals essentially completely divide the nostrils to the exclusion of other bones, which is not seen in the genus of Theriosuchus.[4]
However, the taxonomy of Theriosuchus itself is somewhat convoluted. Most studies have not provided a defined set of characteristics that unite species of Theriosuchus and separate them from other atoposaurids; the only such diagnoses that have explicitly been given were provided by Steve Salisbury and Darren Naish in 2011, and Jeremy Martin and colleagues in 2010.[5] In 2016 Mark Young and colleagues criticized these diagnoses, noting that many characters were either more widely distributed among the Atoposauridae, difficult to assess, or - in the case of the latter diagnosis - not present at all. Young et al. provided an alternative diagnosis containing nine traits, mostly involving teeth; however, they also noted that there was variation among the expression of these traits, which calls into question the monophyly of Theriosuchus.[6] K. langenbergensis differs from this diagnosis in four out of nine traits, which Schwarz et al. cited as a basis for both the generic separation of Knoetschkesuchus and the necessity of revising the diagnosis further.[1]
According to Schwarz et al., seven traits unite K. langenbergensis and K. guimarotae, and separate them from other species referred to Theriosuchus. These include the presence of only two unique tooth morphotypes; the choanae being placed in shallow grooves rather than a bowl-like depression; the relatively wide top of the skull; the presence of antorbital and mandibular fenestrae in all life stages; and the relatively limited contact between the lacrimal and nasal. Additionally, K. langenbergensis differs from other species in lacking leaf-shaped or "pseudoserrated" teeth; lacking teeth with low crowns; having a longer maxillary symphysis; having a crest on the side of the downward-projecting process of the postorbital; having overlap between the postorbital and the front of the squamosal; and a rectangular parietal that does not form part of the supratemporal fenestra.[1]
In the 2017 description of K. langenbergensis, Schwartz et al. used the 2015 phylogenetic dataset of Alan Turner,[7] which was revised to remove irrelevant characteristics, add K. langenbergensis and T. grandinaris, and correct flaws in the coded traits of K. guimarotae (due to low-resolution images, inaccuracies in the original reconstruction, and the acquirement of new data). The phylogenetic trees recovered by this analysis consistently found that Atoposauridae, represented by Knoetschkesuchus, Theriosuchus, and Alligatorium, forms a monophyletic clade. Within this clade, a close relationship between K. langenbergensis and K. guimarotae, excluding other Theriosuchus species, was strongly supported, providing further evidence of these two species forming a separate genus. In some trees, T. grandinaris was also close to Knoetschkesuchus. The most parsimonious arrangement is reproduced below.[1]
| Eusuchia |
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References
- ^ a b c d e f g h i j k l m n o p q r Schwartz, D.; Raddatz, M.; Wings, O. (2017). "Knoetschkesuchus langenbergensis gen. nov. sp. nov., a new atoposaurid crocodyliform from the Upper Jurassic Langenberg Quarry (Lower Saxony, northwestern Germany), and its relationships to Theriosuchus". PLoS ONE. 12 (2): e0160617. doi:10.1371/journal.pone.0160617.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b c d e f g h i j k l m n o p q r s t u v Schwarz, D.; Salisbury, S.W. (2005). "A new species of Theriosuchus (Atoposauridae, Crocodylomorpha) from the Late Jurassic (Kimmeridgian) of Guimarota, Portugal". Geobios. 38 (6): 779–802. doi:10.1016/j.geobios.2004.04.005.
- ^ Karl, H.-V.; Gröning, E.; Brauckmann, C.; Schwarz, D.; Knötschke, N. (2006). "The Late Jurassic crocodiles of the Langenberg near Oker, Lower Saxony (Germany), and description of related materials (with remarks on the history of quarrying the "Langenberg Limestone" and "Obernkirchen Sandstone")". Clausthaler Geowissenschaften. 5: 59–77.
- ^ a b Tennant, J.P.; Mannion, P.D.; Upchurch, P. (2016). "Evolutionary relationships and systematics of Atoposauridae (Crocodylomorpha: Neosuchia): implications for the rise of Eusuchia". Zoological Journal of the Linnaean Society. 177 (4): 854–936. doi:10.1111/zoj.12400.
- ^ Martin, J.E.; Rabi, M.; Cziki, Z. (2010). "Survival of Theriosuchus (Mesoeucrocodylia: Atoposauridae) in a Late Cretaceous archipelago: a new species from the Maastrichtian of Romania". Naturwissenschaften. 97 (9): 845–854. doi:10.1007/s00114-010-0702-y.
- ^ Young, M.T.; Tennant, J.P.; Brusatte, S.L.; Challands, T.J.; Fraser, N.C.; Clark, N.D.L.; Ross, D.A. (2016). "The first definitive Middle Jurassic atoposaurid (Crocodylomorpha, Neosuchia), and a discussion on the genus Theriosuchus". Zoological Journal of the Linnaean Society. 176 (2): 443–462. doi:10.1111/zoj.12315.
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