[D] Shanyangosaurus niupanggouensis [sG] [T]
Describer
Xue, Zhang & Bi, 1996
Time
Cretaceous Late Maastrichtian
Classification
Saurischia Theropoda
Diet
Carnivore
Fossilsite
Shanyang Formation, Shaanxi, China
Info
Genus - Typespecies
Comments by Mickey Mortimer
Etymology
\\\"Shanyang lizard from Niupanggou\\\", Shanyang being the basin it was found in and Niupanggou the region. Shanyang Formation, Shaanxi, China middle-late Maastrichtian, Late Cretaceous holotype- (NWUV 1111) partial sacrum, proximal scapula, humeri, femur, tibia, metatarsal IV (left and right), partial phalanx, pedal ungual diagnosis- long triangular cnemial crest on tibia projected forward with apex above posterior apexes of tibial condyles. main measurements - humerus 116 mm - femur 258 mm - tibia 327 mm - metatarsal IV 137 mm -
Description
This is a relatively small theropod dinosaur about the size of Velociraptor or Oviraptor, that could have measured from 1.7 to 2.6 meters in length, depending on tail size. It is described very briefly with little relevent information written. Luckily, there are accompanying plates. The text states the bones are hollow. The sacral remains consists of two complete fused vertebrae with the anterior section of a third. Both are 32 mm long and shown in ventral view. The scapula is missing it\\\'s distal end and is very poorly preserved. It would appear to have a low acromion and there is no forward projecting acromion process visible. The humerus is 45% of the femoral length and also very poorly preserved, but appears to heve a more proximally placed deltopectoral crest than most other coelurosaurs (apex 22% down the shaft). The internal tuberosity is not very prominent.
The femur is in general very similar to that figured as Ingenia in The Dinosauria, differing in a couple of ways. It\\\'s a bit more robust, has less of a neck below the head, which is separated from the greater trochantor by less of a groove. The lateral condyle is broken off, as are any remains of the lesser or accessory trochantors, if they existed. The text states that the fourth trochantor is absent and that the intercondylar groove is deep and wide. Importantly, the head is elevated. The tibia is 127% of femoral length and fairly well preserved (it\\\'s a shame more tibial features aren\\\'t used in coelurosaur analyses). It\\\'s also very similar to Ingenia\\\'s, but differs in a couple of ways as well. The shaft is bowed laterally and the cnemial crest is a different shape, being much longer and more prominent, with the anterodorsal edge almost perpendicular to the shaft.
It\\\'s the one reason this taxon isn\\\'t a nomen dubium. (When I was first writing this post, I thought the tibia was backwards, as the cnemial crest is so unique that it looks much more normal if the posterior tibial condyles are the cnemial crest. When viewed that way, the \\\"cnemial\\\" crest is just a bit shorter than Ingenia\\\'s proximodistally and with a more verical anterodorsal edge. I wouldn\\\'t have realized my mistake if not for later noting how large the inner tibial condyle appeared to be and noticing Xue et al. wrote \\\"long cnemial crest without furrow on it\\\'s distal part\\\" in the diagnosis/description.
They may have the tibia backwards, but I\\\'m sure they can tell better than I, as they have the actual three dimensional specimen and not a photocopy.). There is a fibular crest and no depression for the ascending process can be observed. The fourth metatarsal is 53% of femoral length, fairly robust, more so than many other coelurosaurs, and is almost certainly not arctometatarsalian because it\\\'s wider transversely than deep. It is narrower transversely when viewed proximally than Deinonychus. There is also the distal section of a pedal(?) phalanx and another bone, which may be the proximal end of the other fourth metatarsal mentioned as it is roughly similar in proximal view.
The pedal ungual is not as deep as therizinosaurs, but deeper than Nedcolbertia. It\\\'s more curved than ornithimimids, but less so than dromaeosaurids. Of special note is the statement \\\"ribs with horizontal hooks\\\" that is in the description and has fueled thoughts of uncinate processes. Note however, that no ribs are mentioned in the material list, nor are any shown in the plates.
Relationships
Shanyangosaurus was originally identified only to the level of Theropoda and there it has stayed in many people\\\'s minds. Unfortunately, the remains are very poorly preserved and described. Shanyangosaurus is obviously some type of theropod with an unfused non-arctometatarsalian metatarsus, a low acromion and an elevated femoral head. This particular combination of features is only known in oviraptorids, although several other groups could have this combination of features, but are too poorly known to determine. These are Ornitholestes, Caudipteryx, Microvenator, Bagaraatan, Protarchaeopteryx, Alvarezsaurus, Patagonykus, Unenlagia and Rahonavis. Shanyangosaurus has a non-alvarezsaurid humerus, so Alvarezsaurus and Patagonykus are eliminated as possibilities.
The scapula of Shanyangosaurus still has an obvious acromion (and no apparent anteriorly projecting acromion process), so it\\\'s not as bird-like as Unenlagia or Rahonavis yet. Both Ornitholestes and Protarchaeopteryx are not well described or figured enough to compare closely to Shanyangosaurus, although Protarchaeopteryx bears no real resemblence and Ornitholestes is in a phylogenetic position where you would expect it to have a plesiomorphically high acromion. Bagaraatan has a tibia that is wider than deep proximally and a fused tibiotarsus, unlike Shanyangosaurus. Caudipteryx has an anteriorly projected acromion process and much more slender metatarsal IV. Microvenator is more slender with a weaker cnemial crest, but does share the absence of a fourth trochantor with Shanyangosaurus, so they may be related.
So Shanyangosaurus compares closest to Microvenator and oviraptorids and is therefore probably an oviraptorosaur, which is congruent with the horizon and locality, not to mention the currently problematic presence of uncinate processes.
For those of you wondering if there may be some relationship to Nomingia, Shanyangosaurus resembles Ingenia more because Nomingia has a declined femoral head and laterally projected femoral medal condyle. BTW, Nomingia is closer to Caudipteryx than Microvenator or oviraptorids according to my latest analysis, although I\\\'m waiting for the description to be published before I trust this result. I don\\\'t think it\\\'s possible to narrow down Shanyangosaurus\\\'s relationships much further, as it and Microvenator are poorly known and oviraptorids have yet to be described well and sorted out phylogenetically.
There are a few comparisons I can make however. The acromion of Shanyangosaurus does seem higher than Oviraptor philoceratops and it seems to lack the anteriorly projecting process of Caudipteryx. The humerus is 45% of femoral length, which is less than 66% for Microvenator , 61% for Ingenia and ~73% for Oviraptor(?). So if Shanyangosaurus is an oviraptorid, it has a much shorter arm than others (although the basal oviraptorosaur Caudipteryx\\\'s ratio is 47%, so such short arms are not unheard of in this group).
The deltopectoral crest is 22% down the shaft, compared to 30% in Microvenator, 40% in Ingenia and 42% in Oviraptor. Again, less than oviraptorids and Microvenator but on par with Caudipteryx (~25%). On the other hand, the humerus is more robust than either Caudipteryx or Microvenator and closer to Ingenia in this regard.
As said above, both Shanyangosaurus, Caudipteryx and Ingenia have inclined femoral heads, whereas Nomingia does not. Nomingia has a transversely wider greater trochantor than either Ingenia or Shanyangosaurus. Microvenator lacks a fourth trochantor and Shanyangosaurus is supposed to as well, but it may still be present, but very reduced as in oviraptorids.
Regarding the distal femur, Microvenator\\\'s is expanded laterally more than Ingenia\\\'s, Shanyangosaurus\\\'s or Nomingia\\\'s, Nomingia and Ingenia have lateral condyles than project distally, unlike Microvenator and Shanyangosaurus, and Shanyangosaurus has the smallest medial expansion, while Nomingia has the greatest.
If correctly identified (see above), the cnemial crest is much larger and more proximally placed than any other coelurosaur and the posterior tibial condyles are more prominent and distally projecting than oviraptorosaurs. The metatarsal is more robust than Caudipteryx, comparing well to Oviraptor, Conchoraptor and Ingenia. The pedal ungual is not as narrow or sharp as shown for Conchoraptor and has a smaller proximoventral heel than Ingenia, although it\\\'s rather similar to those of Oviraptor
Reference
Xue, Zhang, Bi, Yue and Chen, (1996). The development and environmental changes of the intermontane basins in the Eastern part of Qinling Mountains. Geological Publishing House, Beijing. ISBN 7-116-02125-6. 179 pages. Various species are named, but Shanyangosaurus is only credited to Xue, Zhang and Bi.
Xue, Zhang & Bi, 1996
Time
Cretaceous Late Maastrichtian
Classification
Saurischia Theropoda
Diet
Carnivore
Fossilsite
Shanyang Formation, Shaanxi, China
Info
Genus - Typespecies
Comments by Mickey Mortimer
Etymology
\\\"Shanyang lizard from Niupanggou\\\", Shanyang being the basin it was found in and Niupanggou the region. Shanyang Formation, Shaanxi, China middle-late Maastrichtian, Late Cretaceous holotype- (NWUV 1111) partial sacrum, proximal scapula, humeri, femur, tibia, metatarsal IV (left and right), partial phalanx, pedal ungual diagnosis- long triangular cnemial crest on tibia projected forward with apex above posterior apexes of tibial condyles. main measurements - humerus 116 mm - femur 258 mm - tibia 327 mm - metatarsal IV 137 mm -
Description
This is a relatively small theropod dinosaur about the size of Velociraptor or Oviraptor, that could have measured from 1.7 to 2.6 meters in length, depending on tail size. It is described very briefly with little relevent information written. Luckily, there are accompanying plates. The text states the bones are hollow. The sacral remains consists of two complete fused vertebrae with the anterior section of a third. Both are 32 mm long and shown in ventral view. The scapula is missing it\\\'s distal end and is very poorly preserved. It would appear to have a low acromion and there is no forward projecting acromion process visible. The humerus is 45% of the femoral length and also very poorly preserved, but appears to heve a more proximally placed deltopectoral crest than most other coelurosaurs (apex 22% down the shaft). The internal tuberosity is not very prominent.
The femur is in general very similar to that figured as Ingenia in The Dinosauria, differing in a couple of ways. It\\\'s a bit more robust, has less of a neck below the head, which is separated from the greater trochantor by less of a groove. The lateral condyle is broken off, as are any remains of the lesser or accessory trochantors, if they existed. The text states that the fourth trochantor is absent and that the intercondylar groove is deep and wide. Importantly, the head is elevated. The tibia is 127% of femoral length and fairly well preserved (it\\\'s a shame more tibial features aren\\\'t used in coelurosaur analyses). It\\\'s also very similar to Ingenia\\\'s, but differs in a couple of ways as well. The shaft is bowed laterally and the cnemial crest is a different shape, being much longer and more prominent, with the anterodorsal edge almost perpendicular to the shaft.
It\\\'s the one reason this taxon isn\\\'t a nomen dubium. (When I was first writing this post, I thought the tibia was backwards, as the cnemial crest is so unique that it looks much more normal if the posterior tibial condyles are the cnemial crest. When viewed that way, the \\\"cnemial\\\" crest is just a bit shorter than Ingenia\\\'s proximodistally and with a more verical anterodorsal edge. I wouldn\\\'t have realized my mistake if not for later noting how large the inner tibial condyle appeared to be and noticing Xue et al. wrote \\\"long cnemial crest without furrow on it\\\'s distal part\\\" in the diagnosis/description.
They may have the tibia backwards, but I\\\'m sure they can tell better than I, as they have the actual three dimensional specimen and not a photocopy.). There is a fibular crest and no depression for the ascending process can be observed. The fourth metatarsal is 53% of femoral length, fairly robust, more so than many other coelurosaurs, and is almost certainly not arctometatarsalian because it\\\'s wider transversely than deep. It is narrower transversely when viewed proximally than Deinonychus. There is also the distal section of a pedal(?) phalanx and another bone, which may be the proximal end of the other fourth metatarsal mentioned as it is roughly similar in proximal view.
The pedal ungual is not as deep as therizinosaurs, but deeper than Nedcolbertia. It\\\'s more curved than ornithimimids, but less so than dromaeosaurids. Of special note is the statement \\\"ribs with horizontal hooks\\\" that is in the description and has fueled thoughts of uncinate processes. Note however, that no ribs are mentioned in the material list, nor are any shown in the plates.
Relationships
Shanyangosaurus was originally identified only to the level of Theropoda and there it has stayed in many people\\\'s minds. Unfortunately, the remains are very poorly preserved and described. Shanyangosaurus is obviously some type of theropod with an unfused non-arctometatarsalian metatarsus, a low acromion and an elevated femoral head. This particular combination of features is only known in oviraptorids, although several other groups could have this combination of features, but are too poorly known to determine. These are Ornitholestes, Caudipteryx, Microvenator, Bagaraatan, Protarchaeopteryx, Alvarezsaurus, Patagonykus, Unenlagia and Rahonavis. Shanyangosaurus has a non-alvarezsaurid humerus, so Alvarezsaurus and Patagonykus are eliminated as possibilities.
The scapula of Shanyangosaurus still has an obvious acromion (and no apparent anteriorly projecting acromion process), so it\\\'s not as bird-like as Unenlagia or Rahonavis yet. Both Ornitholestes and Protarchaeopteryx are not well described or figured enough to compare closely to Shanyangosaurus, although Protarchaeopteryx bears no real resemblence and Ornitholestes is in a phylogenetic position where you would expect it to have a plesiomorphically high acromion. Bagaraatan has a tibia that is wider than deep proximally and a fused tibiotarsus, unlike Shanyangosaurus. Caudipteryx has an anteriorly projected acromion process and much more slender metatarsal IV. Microvenator is more slender with a weaker cnemial crest, but does share the absence of a fourth trochantor with Shanyangosaurus, so they may be related.
So Shanyangosaurus compares closest to Microvenator and oviraptorids and is therefore probably an oviraptorosaur, which is congruent with the horizon and locality, not to mention the currently problematic presence of uncinate processes.
For those of you wondering if there may be some relationship to Nomingia, Shanyangosaurus resembles Ingenia more because Nomingia has a declined femoral head and laterally projected femoral medal condyle. BTW, Nomingia is closer to Caudipteryx than Microvenator or oviraptorids according to my latest analysis, although I\\\'m waiting for the description to be published before I trust this result. I don\\\'t think it\\\'s possible to narrow down Shanyangosaurus\\\'s relationships much further, as it and Microvenator are poorly known and oviraptorids have yet to be described well and sorted out phylogenetically.
There are a few comparisons I can make however. The acromion of Shanyangosaurus does seem higher than Oviraptor philoceratops and it seems to lack the anteriorly projecting process of Caudipteryx. The humerus is 45% of femoral length, which is less than 66% for Microvenator , 61% for Ingenia and ~73% for Oviraptor(?). So if Shanyangosaurus is an oviraptorid, it has a much shorter arm than others (although the basal oviraptorosaur Caudipteryx\\\'s ratio is 47%, so such short arms are not unheard of in this group).
The deltopectoral crest is 22% down the shaft, compared to 30% in Microvenator, 40% in Ingenia and 42% in Oviraptor. Again, less than oviraptorids and Microvenator but on par with Caudipteryx (~25%). On the other hand, the humerus is more robust than either Caudipteryx or Microvenator and closer to Ingenia in this regard.
As said above, both Shanyangosaurus, Caudipteryx and Ingenia have inclined femoral heads, whereas Nomingia does not. Nomingia has a transversely wider greater trochantor than either Ingenia or Shanyangosaurus. Microvenator lacks a fourth trochantor and Shanyangosaurus is supposed to as well, but it may still be present, but very reduced as in oviraptorids.
Regarding the distal femur, Microvenator\\\'s is expanded laterally more than Ingenia\\\'s, Shanyangosaurus\\\'s or Nomingia\\\'s, Nomingia and Ingenia have lateral condyles than project distally, unlike Microvenator and Shanyangosaurus, and Shanyangosaurus has the smallest medial expansion, while Nomingia has the greatest.
If correctly identified (see above), the cnemial crest is much larger and more proximally placed than any other coelurosaur and the posterior tibial condyles are more prominent and distally projecting than oviraptorosaurs. The metatarsal is more robust than Caudipteryx, comparing well to Oviraptor, Conchoraptor and Ingenia. The pedal ungual is not as narrow or sharp as shown for Conchoraptor and has a smaller proximoventral heel than Ingenia, although it\\\'s rather similar to those of Oviraptor
Reference
Xue, Zhang, Bi, Yue and Chen, (1996). The development and environmental changes of the intermontane basins in the Eastern part of Qinling Mountains. Geological Publishing House, Beijing. ISBN 7-116-02125-6. 179 pages. Various species are named, but Shanyangosaurus is only credited to Xue, Zhang and Bi.