So, I'm trying to represent these things as best I can, but despite being extinct, they aren't letting themselves be pinned down very well. Especially Euhelopus. Have you ever tried to pin down Euhelopus?  You'd think it would be easy, but it's a slippery beast.
    Anyway, I had to do something before the Sauropoda page got too large, and this is the result. At any rate, once the "Mamenchisaurus"/"Omeisaurus" complex gets sorted out, we'll probably have a much better idea of relationships, so don't get too worked up about this part of the tree.

                |--"Omeisaurus" tianfuensis
                     |    |--Galveosaurus
                     |    `--+--Losillasaurus
                     |         `--Turiasaurus

Eusauropoda: The eusauropods are a step more derived compared to the vulcanodontids and their ilk. They have begun to develop very extensive lightening efforts on their verts. Several of the better-known forms (Cetiosaurus, Patagosaurus, and "Mamenchisaurus") could form a family on their own.  

Taxon or Taxa: Time/Place: Comments:
Shunosaurus lii Dong, Zhou, and Zhang, 1983 Bathonian-Callovian (MJ) of China Shunosaurus is one of the best represented sauropods. Remains pertaining to over twenty individuals have been found, with several skulls. Shunosaurus is a very primitive sauropod, but has one very unique characteristic, a spiky club on the end of its tail. It was once known under the unofficial name "Shuosaurus". The snout widened and rounded with age, from a more prosauropod-like start, and the tooth enamel is apparently less derived than that of Omeisaurus
Cetiosaurus oxoniensis Phillips, 1871 (genus named in Owen, 1841) Bathonian (MJ) of England C. oxoniensis is much better known than the original type of Cetiosaurus ("C." medius). Most representations of Cetiosaurus are drawn from this taxon. It's kind of an average sauropod.
Patagosaurus fariasi Bonaparte, 1979 Aalenian-Bathonian (MJ) of Argentina Known from specimens from a dozen individuals, Patagosaurus is one of the better known basal eusauropods. However, some of the referred material apparently belongs to a different type of sauropod.
Chuanjiesaurus anaensis Fang, Pang, Lu, Zhang, Pan, Wang, Li, and Cheng, 2000 early MJ of China This large, newly-described taxon was referred to as a cetiosaurid. It is known from postcranial remains, including a scapula, humerus, numerous caudals, and forked chevrons. Remains from possibly three individuals are known, the largest possibly 25 meters in length (quite long for an early sauropod).
"Mamenchisaurus": "M." anyuensis He, Yang, Cai, Li, and Liu, 1996 LJ of China Another day, another possible species of Mamenchisaurus. This one is known from multiple partial skeletons, and is based on a fairly complete postcranial specimen, comparable in size to "M." hochuanensis. In most anatomical characteristics, it is comparable to that species as well. The presacrals are opisthocoelous and have weakly bifid neural spines.
"M." hochuanensis Yang and Zhao, 1972 Oxfordian (LJ) of China This is the long-necked animal often illustrated for Mamenchisaurus proper (see below under Eusauropoda i.s.), being another case like Brachiosaurus/Giraffatitan where a second species is better known than the type. A sort of trough is also present on top of the neural spines, as well as in Euhelopus and possibly Tienshanosaurus. The tail featured a quasi-club of a few fused vertebrae.
"M." sinocanadorum Russell and Zheng, 1993 Oxfordian (LJ) of China For some reason I'd included this species in "M." hochuanensis for many years (I swear I remember reading something about it, but I can't remember where). This species is known from practically the entire specimen, and earned a small historical footnote by showing that this sort of animal had a short, camarasaurid-like skull instead of a diplodocid-like skull; back in the 1980s, Mamenchisaurus was thought to be a diplodocid-like animal because it had diplodocid-like skid-like chevrons. It is also of note for its great size; mounted specimens are on the order of 35 m (115 ft) long, about half of which is neck.
"M." youngi Pi, Ou, and Ye, 1996 Oxfordian (LJ) of China "M." youngi is based a skull and most of a skeleton including some skin impressions. It has bifurcated neural spines on some cervicals and dorsals, in the Euhelopus "low trough" mode, and the presacrals are opisthocoelous, while the caudals go from procoelous to amphiplatyan; unfortunately, the chevrons are not described. The skull bears an uncanny resemblance to some specimens of Camarasaurus, albeit a bit longer-faced. Restorations have the hip and tail oriented with a distinct upward trajectory from the back.
"Omeisaurus" tianfuensis He, Li, Cai, and Gao, 1984 Bathonian-Callovian (MJ) of China This is the dinosaur often used for illustrations of Omeisaurus, which is incorrect. Just comparing the skulls of this and the type species of Omeisaurus shows how much this is wrong (either that, or an artist was in the wrong field). It was a very long-necked animal.
Qijianglong guokr Xing L., Miyashita, Zhang J., Li D., Ye Y., Sekiya, Wang F., and Currie, 2015 LJ of Chongqing, China Qijianglong is known from the partial skeleton of an immature individual, including part of the skull, the cervical series, some dorsals, a significant chunk of the tail, fragments of ribs and chevrons, the left pubis, and one lonely toe bone to represent the limbs. It was a long-necked sauropod in the vein of Omeisaurus and Mamenchisaurus (whatever they actually constitute).
Xinjiangtitan shanshanesis Wu W. H., Zhou C., Wings, Sekiya, and Dong, 2013 MJ of China Xinjiangtitan is a large "mamenchisaurid" (I use the term in quotes because what exactly Mamenchisaurus is remains to be established), on the order of 30 m/100 ft in length. It is known from a partial skeleton, most of which is articulated or associated axial skeleton; you get a couple of cervicals, the dorsals and sacrals, a couple of caudals, miscellaneous ribs, much of the pelvis, and the long bones of the left leg. The hind limb is proportionally short.

Eusauropoda i.s.:

Taxon or Taxa: Time/Place: Comments:
Amygdalodon patagonicus Cabrera, 1947 ?Toarcian-Bajocian (?EJ-MJ) of Argentina Amygdalodon is based on partial remains of at least three individuals.  These remains are "cetiosaurid", but not particularly enlightening about further classification.
Bellusaurus sui Dong, 1990 mid Bathonian-late Callovian (MJ) of China This sauropod is based upon the remains of 17 juveniles, and likely is the juvenile of an already-known sauropod. It could be a basal macronarian, related to the brachiosaurids.
Bothriospondylus suffossus (N.D.) Owen, 1875 early Kimmeridgian (LJ) of England Based on vertebrae and not particularly well known, this sauropod has historically been regarded as close to Brachiosaurus (well, since there have been brachiosaurids, of course).
"Bothriospondylus" madagascariensis Lydekker, 1895 Bathonian (MJ) of Madagascar; late Oxfordian (LJ) of France "Bothriospondylus" madagascariensis has a complicated history. The true Madagascar stuff is often mixed up with Lapparentosaurus madagascariensis, which unfortunately has the same species name. It appears that there were three contemporaneous genera in the Bathonian of Madagascar (Archaeodontosaurus, "Bothriospondylus", and Lapparentosaurus), although a name has not yet been given to the "Bothriospondylus" material.
Meanwhile, remains from somewhat younger rocks in France have also been referred to this species. These may also be diagnostic, and appear to have come from a brachiosaurid.
Cetiosauriscus stewarti Huene, 1927 (species after Charig, 1980) mid-late Callovian (MJ) of England Named from remains once assigned to Cetiosaurus, this animal may instead be a basal diplodocoid, or, alternatively, a much more basal sauropod. Among other things, it has the characteristic chevrons.
?"Cetiosaurus" glymptonensis (?N.D.) Phillips, 1871 late Bathonian (MJ) of England Sometimes referred to Cetiosauriscus, there is little evidence to support this. Alternately, it may be a basal diplodocoid, but again there is little evidence to support this. It is based on caudal centra.
Chebsaurus algeriensis Mahammed, Läng, Mami, Mekahl, Benhamou, Bouterfa, Kacemi, Chérief, Chaouati, and Taquet, 2005 MJ of Naâma, Algeria This basal eusauropod is based on a partial skeleton and skull of a partially-grown, 8-9 meter long individual (the name is actually from an informal Arab word for "teenager"). It is important because of the generally poor remains of dinosaurs in the EJ and MJ, just when they were undergoing some interesting evolution. Remains include a partial braincase and lower jaw, eight partial cervicals, six partial dorsals, a sacral, three caudals, a scapula, most of a forelimb, a partial ilium, a pubis, a partial fibula, and most of a hind foot. 
"Chondrosteosaurus" magnus Owen, 1876 Barremian (EK) of England This is an indeterminate Wealden eusauropod based on a dorsal, not to be confused with Bothriospondylus magnus (an invalid name for Ornithopsis hulkei).
Daanosaurus zhangi Ye, Gao, and Jiang, 2005 LJ of China Apparently close to Bellusaurus (not surprisingly, it seems that both are based on juvenile remains), this animal is based on skull and postcranial material including vertebrae and limb elements.
Dashanpusaurus dongi Peng, Ye, Gao, Shu, and Jiang, 2005 Bathonian-Callovian (MJ) of China  This sauropod has been identified as a camarasaurid, but since that family is a little defunct at the moment, I'm leaving it as Eusauropoda i.s., possibly a basal macronarian. Interestingly, both of its published specimens lack skulls, whereas possible basal macronarian Abrosaurus has a poorly-described body with no mentioned characters that deviate from the Dashanpusaurus description... Call that my crazy thought for the page.
As mentioned, two specimens have been described, one being a good chunk of the vertebral column with ribs, an ulna, pelvic girdle, and a hindlimb, and the other is composed of 12 dorsals, ribs, left pectoral girdle, and left humerus and radius (neatly filling in the rest of the arm bar the hand, but we can't have everything). Among other characters, the known cervicals are short, and the caudal cervicals and cranial dorsals have slight splitting of the neural spines, like several other MJ/LJ Chinese sauropods. 
Datousaurus bashanensis Dong and Tang, 1984 Bathonian-Callovian (MJ) of China Datousaurus is much rarer than its contemporaries Shunosaurus and Omeisaurus. In many ways it converges on the condition one would expect for a basal diplodocoid, but a possible skull is very robust and un-diplodocoid. For a basal sauropod, it is rather long, on the order of 50 feet long.
Dystrophaeus viamalae (?N.D.) Cope, 1877 Oxfordian (LJ) of Utah Dystrophaeus is historically notable as the first sauropod described from North America. At the time the only known specimen was discovered, the skeletal remains could not be entirely excavated, with only a forelimb and scapula recovered in the first go-round. It is one of the few dinosaurs known from the Tidwell Member, which makes up part of either the Morrison Formation or underlying Summerville Formation. Historically it was considered as a "cetiosaurid," but more recently a diplodocoid or diplodocid identity has been proposed.
Eomamenchisaurus yuanmouensis Lü J., Li T., Zhong S., Ji Q., and Li S., 2008  Aalenian-Bajocian (MJ) of China Described as a mamenchisaurid related to "M." hochuanensis and youngi, and Chuanjiesaurus, this sauropod is known from vertebral, girdle, and limb remains.
Huangshanlong anhuiensis Huang J.-D., You H.-L., Yang J.-T., and Ren X.-X., 2014 MJ of China This eusauropod was described as a mamenchisaurid, which still leaves open the question of what exactly Mamenchisaurus is, as well as Omeisaurus, for that matter. It is known from a humerus, radius, and ulna.
Hudiesaurus sinojapanorum Dong, 1997 MJ of China This obscure sauropod is apparently very, very large. The vertebrae it is based on show slight signs of bifurcation, suggesting a relationship with Euhelopus, Mamenchisaurus, and "Mamenchisaurus", which also had shallow bifurcation. Some other material, including a forelimb and teeth, was referred to it, but this material was not in association.
Klamelisaurus gobiensis Zhao, 1993 mid Bathonian-late Callovian (MJ) of China This sauropod converges in some way with the brachiosaurids. It has also been suggested as the adult form of Bellusaurus.
Liubangosaurus hei Mo J., Xu X., and Buffetaut, 2010 EK of China Liubangosaurus is an eusauropod known from five articulated caudal dorsals.
Mamenchisaurus constructus Yang, 1954 Oxfordian (LJ) of China This sauropod is famous for its extremely long neck. Ironically, the species that was best known for this, "M." hochuanensis (see above) exhibits many differences from the type and probably doesn't belong. That said, this animal is still very long-necked. A number of N.N. species have been referred to the genus, but as they would tend to increase the clutter here for no good reason, I have left them out. The type species is known to have had forked chevrons and bifid presacral neural spines.
"Mamenchisaurus": "M." jingyanensis Zhang, Li, and Zheng, 1998 Oxfordian (LJ) of China This large species appears to be different from both Mamenchisaurus and "M." hochuanensis; among other differences, its dorsal vertebrae are procoelous, while those of the other two taxa mentioned are opisthocoelous. Bifid presacral spines are present. The hollows in its vertebrae are poorly developed, suggesting that this is a rather basal sauropod. It is known from a partial skull, which is relatively long and low and appears fairly basal as far as sauropod skulls are concerned, and some postcranial material.
"M." yunnanensis (N.D.) Fang X., Zhao X., Lu L., and Cheng Z., 2004 ?LJ of China I am tentatively accepting this as published, although as with all species assigned to Mamenchisaurus, I regard the assignment as unproven. It is based on fragmentary material including girdle and limb bones, and is mostly of interest for providing evidence of the presence of Upper Jurassic rocks in the Lufeng Basin (if, indeed, it has much of anything to do with Mamenchisaurus).
Omeisaurus junghsiensis
Yang, 1939
Bathonian-Callovian (MJ) or Oxfordian (LJ) of China Omeisaurus proper is known from several partial skeletons and a skull, restorations of which do not particularly resemble any other known sauropod skull: it comes out in lateral view as almost triangular, with the antorbital, orbital, and infratemporal openings as three large artistically-composed triangles of space, lined up and alternating up-down-up points, and a relatively diminutive nasal fenestra that promoted no nasal arch or similar structure. What it constitutes has not yet been fully addressed.
"Omeisaurus": "O." changshouensis (N.D.) Yang, 1958 Oxfordian (LJ) of China This animal appears to be closer to Mamenchisaurus or "Mamenchisaurus" than to Omeisaurus. It has been a continual problem. It is based on a handful of dorsals and cervicals, partial shoulder and pelvic girdles, a humerus, and several hindlimb bones.
"O." jiaoi Jiang S., Li F., Peng G.-Z., and Ye Y., 2011 Bathonian-Callovian (MJ) of China "O." jiaoi is known from most of an articulated to associated skeleton including much of the back and tail, the pelvic girdle and hind limbs, half of the shoulder girdle, and most of the arms. The dorsals are opisthocoelous and have unbifurcated neural spines, and the anterior caudals are amphicoelous.
"O." luoquanensis (N.D.) Li, 1988 Bathonian-Callovian (MJ) of China Like other species referred to Omeisaurus, this one may or may not belong here. It is based on a partial skeleton, mostly neural spines and caudals, with a few limb and girdle bones.
"O." maoianus Tang, Jin, Kang, and Zhang, 2001 Bathonian-Callovian (MJ) of China This animal is known from a complete skull and partial postcranium including three cervicals, four dorsals, twenty-two caudals, most of the pelvic girdle, and most of the limbs. The presacral neural spines show no bifurcation, and the presacrals are opisthocoelous. The skull is short, without much of a snout, and does not particularly resemble the skulls of "O." tianfuensis or O. junghsiensis, being vaguely camarasaur-like as opposed to boxy basal sauropod or an odd wedge, respectively. It may be more derived than the former.
"Ornithopsis" greppini (?N.D.) Huene, 1922 early Kimmeridgian (LJ) of Switzerland Uh, it's a Swiss dinosaur; you don't see that that often... and nobody ever really talks about it... and it's based on the partial remains of multiple individuals, so maybe if someone looked, it might be useful... and it was once assigned to Cetiosauriscus.
Tendaguria tanzaniensis Bonaparte, Heinrich, and Wild, 2000 Tithonian (LJ) of Mtwara, Tanzania A new Tendaguru sauropod, Tendaguria is based on cranial dorsal vertebrae with single spines. It seems to be related to Camarasaurus.
A dorsal centrum from the Hauterivian-Barremian (EK) of Croatia is similar. 
Tienshanosaurus chitaiensis Yang, 1937 Oxfordian (LJ) of China Known from a partial postcranial skeleton, Tienshanosaurus is one of the first Chinese sauropods known from good remains and still one of its more obscure.
Tonganosaurus hei Li K., Yang C., Liu J., and Wang Z., 2010 EJ of China Tonganosaurus was described as a mamenchisaurid, although I choose to remain agnostic on such matters until it is determined what precisely Mamenchisaurus is. Tonganosaurus is known from verts, pectoral and pelvic material, and bones from the fore and hindlimbs. It joins the small but growing roster of EJ sauropods.
Volkheimeria chubutensis Bonaparte, 1979 Aalenian-Bathonian (MJ) of Argentina A member of an important early sauropod fauna, Volkheimeria is a primitive sauropod with some features possibly like those of brachiosaurids.
Yuanmousaurus jiangyiensis Lu, Li, Ji Q., Wang G., Zhang J., and Dong, 2006 Aalenian-Bajocian (MJ) of China This eusauropod is based on a partial skeleton, including a partial cervical, 9 dorsals, parts of 3 sacrals, 7 caudals, both scapulae, an ilium, and most of a right arm and leg (except the hands and feet). It seems to be somewhere between Omeisaurus and Euhelopus. Features of the dorsals and scapulae, and other details, suggest a particularly close relationship with Patagosaurus ("no, actually, they're just good friends"), although Patagosaurus could stand a good redescription before we go too crazy. For an MJ sauropod, it got up to a decent size, in the 15-20 m range long. The authors assigned it to the Euhelopodidae, but we all know what I think about that family.
Zigongosaurus fuxiensis Hou, Zhao, and Chu, 1976 (?Mamenchisaurus, "Mamenchisaurus", Omeisaurus, or "Omeisaurus") ?Oxfordian (LJ) of China As can be seen, this taxon has very little "job security."  Because it is uncertain what the sauropods listed as possible synonyms constitute, the original genus is retained. It is known from sediments that are roughly between the age of those Omeisaurus is found in and those Mamenchisaurus is found in. It is based on a few skull bones, with bonebed material added. Its neural spines show some bifurcation, but apparently its chevrons were simple (it can be difficult to tell what is going on, because a species of Omeisaurus was described with the same species name a few years later, with the implication that the two "fuxiensis"-es had something to do with each other). At one time, it was suggested to be a brachiosaurid.

Turiasauria: This new group of sauropods illustrates an unexpected division in sauropod diversity and clears up problems regarding some of the more poorly-known members, much like Abelisaurus and Carnotaurus did for theropods in the 1980s and 1990s. While only three sauropods are officially members, several other MJ-EK European sauropods are suggested to belong (Cardiodon, Neosodon, Oplosaurus), and more will doubtless be recognized in the coming years.

Taxon or Taxa: Time/Place: Comments:
Galveosaurus herreroi Sánchez-Hernández, 2005
(includes Galvesaurus herreroi Barco, Canudo, Cuenca-Bescós, and Ruiz-Omeñaca, 2005)
Tithonian-Berriasian (LJ-EK) of Spain Galveosaurus seems closest to basal eusauropods like Cetiosaurus and Barapasaurus, although much later than either. It is known from two humeri, a sternal plate, an ischium, a scapula, a cervical, a caudal dorsal, five caudals, a chevron, and some rib bits. The name actually cropped up several years ago in the EuroDino DB Project feature of Dinodata, when it was probably either a manuscript name or museum name (if you peek through museum databases, you'll sometimes find early names that were changed, or names that are unpublished). 
There has been a controversy here: apparently, Sánchez-Hernández was not the researcher who was working on this taxon, but named it anyway, as Galveosaurus. Meanwhile, members of the research team working on the fossils from this locality, Barco, Canudo, Cuenca-Bescós, and Ruiz-Omeñaca, published Galvesaurus. Sánchez-Hernández has said that her version has priority because it was published on a specific date, and was picked up by the Internet (including this site, which was cited in her appeal) and other publications before Galvesaurus. Galvesaurus was published in a source that claimed July-December 2005 as its issuance, whereas Galveosaurus came out in August.
Losillasaurus giganteus Casanovas, Santafe, and Sanz, 2001 middle Tithonian-early Berriasian (LJ-EK) of Spain Based on a caudal vert, with cranial fragments, numerous vertebrae, a forelimb, pelvis girdle, and sternal plates referred to it, Losillasaurus was initially described as a diplodocoid, then close to Flagellicaudata. It now appears to be a turiasaurian. It comes from a formation near the J-K boundary, thus the uncertain time given.
Turiasaurus riodevensis Royo-Torres, Cobos, and Alcalá, 2006 Tithonian-Berriasian (LJ-EK) of Spain I keep note of unpublished dinosaurs and dinosaur research in an offline file, and this one had hung around for a couple of years as "Riodevasaurus". It's extremely large, especially for a European sauropod, and reasonably well-represented across the body. Remains include a partial skull (a fairly deep affair, probably with honking great nares), teeth, a variety of vertebrae, a sternal plate, a left arm and hand, tibia, fibula, and foot, and ribs. Unfortunately, it's hard to get to the eye-catching stats (length, mass) without an idea of the overall proportions. For example, there's not enough vertebrae to know how long the tail was. Did this animal have a long, lean diplodocid-like build, a stocky titanosaur-like build, or a neck-heavy tall brachiosaur-like build, or something different?
It also gets to found a whole new sauropod lineage, previously unsuspected. 

Turiasauria i.s.:

Taxon or Taxa: Time/Place: Comments:
Atlasaurus imelakei Monbaron, Russell, and Taquet, 1999 ?late Bathonian (MJ) of Morocco Based on a nearly complete skeleton originally referred to Cetiosaurus mogrebiensis, this animal has been considered to be a basal brachiosaurid close to Brachiosaurus's ancestry, or, more recently, a turiasaurian.
Cardiodon rugulosus (?N.D.) Owen, 1844 late Bathonian (MJ) of England Based on a tooth, this taxon has long been referred to Cetiosaurus, which may be true but cannot be proven because no definite skull material has been found for European Cetiosaurus. In fact, recent study suggests that Cardiodon is not referable to Cetiosaurus and may represent a valid taxon based on its unique form. It could be a turiasaurian.
Neosodon [no species name] (N.D.) Moussaye, 1885 Kimmeridgian (LJ) of France Based on a spoon-shaped tooth and usually tossed off as an indeterminate brachiosaurid, additional remains from the area suggest that it may have actually been a large "camarasaurid" or turiasaurian. However, since the type is only a tooth, it is hard to make the identification stick. It is sometimes listed as N. praecursor, with the teeth from "Iguanodon" praecursor assigned to it, but spoon-shaped sauropod teeth are very common.
Oplosaurus armatus (?N.D.) Gervais, 1852 Barremian (EK) of England This is another poorly known Wealden sauropod, based on a large tooth sometimes ascribed to Pelorosaurus, but which may represent a late turiasaurian.  
The story of its name goes that it was compared to Hylaeosaurus, and thus the name means "armored lizard". However, it was actually compared to Mosasaurus (giant sea lizard), so the name could mean "armed lizard". 
Zby atlanticus Mateus, Mannion, and Upchurch, 2014 late Kimmeridgian (LJ) of Portugal Zby, named for paleontologist Georges Zybszewski, is known primarily from most of an arm, although a partial cervical neural arch, chevron, and typical turiasaurian tooth have also been found.

Neosauropoda i.s.:

Taxon or Taxa: Time/Place: Comments:
Ferganasaurus verzilini Alifanov and Averianov, 2003 Callovian (MJ) of Kyrgyzstan Ferganasaurus is a basal neosauropod known from a partial skeleton consisting of a variety of material from behind the neck. It was first excavated back in 1966, but remained undescribed until recently. Some other material, including a spatulate tooth, may be referable, and all in all this animal appears to be a Jobaria-like creature close to the major splittings of the derived sauropod clades. One unusual character is the possession of two large claws per hand.  
"Ischyrosaurus" manseli (N.D.) Hulke 1874 (species vide Lydekker, 1888) Kimmeridgian (LJ) of England A dubious LJ European sauropod based on a humerus, this is traditionally thought to be a brachiosaurid, but it could be a basal titanosauriform of a different stripe, or a rebbachisaurid (which would make it the oldest known member).
Xenoposeidon proneneukos Taylor and Naish, 2007 Berriasian-Valanginian (EK) of England  Xenoposeidon is based on a very unusual partial posterior dorsal vert that had sat around for over a century in the collections of the Natural History Museum in London. The preserved portion of the neural spine is sloped forward at 35°, with a base running the entire length of the centrum, and large areas of the sides are strikingly featureless. This animal does not fit well into any known group of neosauropods; it might be a basal somphospondyl.

Historical Note: I used to have a page on Euhelopodidae, also known as the rest home for Jurassic Asian sauropods that people refer to a lot but generally don't know much about. For fun, here's what I had to say, and a phylogeny proposed out of something less than whole cloth.

Euhelopodidae, while not universally accepted, may be a valid family of sauropods. The reason for doubt of their situation probably stems from several things: most of these sauropods have been little mentioned in English-language publications; they have not yet been subjected to the same sort of rigorous examination other dinosaurs have; and they show a wide variety of convergences with other sauropods, such as the long arms of Euhelopus and the long arms of macronarians, the skid-like chevrons of Mamenchisaurus and the skid-like chevrons of diplodocids, and so on. Cases can be made for aligning the members of this group to just about every other sauropod group. Taxonomically, I have problems with many assignments in this family; thus, I typically separate species from genera here. At this point, euhelopodid taxonomy is at a similar place to where taxonomy of Morrison sauropods was about a hundred years ago: uncertain, poorly understood, and cluttered.
    Having said that, these sauropods do show many similarities. Long necks and longish arms are a common characteristic, as are skid-like chevrons. The skulls are mostly Camarasaurus-like, boxy and with spoon-like teeth. Some advanced members have shallow troughs on the tops of some of their cervical and dorsal verts' neural spines, converging with the better-developed bifid (split) neural spines of camarasaurids and diplodocoids. Euhelopodids also seem to have done much of their evolution in isolation, in a section of eastern Asia which was cut off from the rest of the world from most of MJ through early EK time (although reports of euhelopodid-type teeth have come from Kansas and the Barremian of Spain). It is not impossible that several distinct lines of sauropods came to China before it was isolated, and that this is the reason for many unusual body plans. For example, Euhelopus could be an early offshoot of the titanosaurian line, Mamenchisaurus an offshoot of the diplodocoid line, and so on. This question has yet to be resolved. The question of where on the sauropod line a unified Euhelopodidae belongs is uncertain as well; three favorite places are just below Neosauropoda, somewhere near the diplodocoids, and twinned with the titanosaurians.  I now have them as eusauropods, which seems most conservative.   

                |--"Omeisaurus" tianfuensis
                |--?"O." maoianus
                     |--?"Omeisaurus" changshouensis
                     `--+--"Mamenchisaurus" hochuanensis
                          `--"M" youngi

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