The lambeosaurines are the
hollow-crested hadrosaurids. On the whole, they are more robust in build when
compared to the saurolophines, and tend to have more elongated neural spines than the
saurolophines, giving them more of a fin-back. In North America, they are most common in the
fauna (Corythosaurus could be the poster-hadrosaurid for Dinosaur
Provincial Park), are less common in the Edmontonian,
and finally are almost unknown in the Lancian (possible
remains in the Hell Creek Formation of Montana),
suggesting that they virtually disappear altogether before the end of the
Mesozoic. It had been thought that lambeosaurines went extinct in the early
Maastrichtian, based on North American remains. In recent years,
though, a diverse late Maastrichtian fauna from the Chinese-Russian border in
the Amur River region has been described, including Amurosaurus, Charonosaurus,
The function or functions of the lambeosaurine crest has long been debated. When hadrosaurids were considered to have been water-dwellers, the crests of lambeosaurines, especially that of Parasaurolophus, were drafted into service as possible snorkels or air-traps to increase underwater feeding time. Other proposed uses included foliage deflectors for aiding forest running, salt glands, and extra space for the sense of smell. Today, it is believed that they were primarily display and signaling devices, useful to gregarious animals, which hadrosaurids appear to be. The hollow spaces in the crests, connected to the windpipe and nostrils, could have produced low-pitched honks when the animal breathed in a certain way, and the crests themselves could have been very colorful or have provided attachments to colorful skin sails. In the better-known lambeosaurines, crest forms believed to belong to juveniles, adult males, and adult females have been identified, with the adult male crests most prominent and the female and juvenile gear more subdued. The crests appear to have begun growth from in front of the eyes as bulges, giving some juveniles a vague resemblance to Gryposaurus in external skull morphology.
It is also probable that beside signaling and display, the crests had other functions. Some auxiliary functions suggested include thermoregulation (somewhat like what some stegosaurians may have done with their plates), improving the sense of smell, and warming the air breathed in.
Lambeosaurines can be divided into two general groups: Parasaurolophini and Lambeosaurini (a.k.a. Corythosaurini). Parasaurolophini is as yet not as populous as Lambeosaurini, which is composed of several closely-related taxa. In fact, it has been suggested that Lambeosaurus, Corythosaurus, and Hypacrosaurus are similar enough to each other to allow for them to be classified under the same genus: Hypacrosaurus.
| | `--Blasisaurus
Basal Lambeosaurinae, Aralosaurini, and Tsintaosaurini:
|Taxon or Taxa:||Time/Place:||Comments:|
|Aralosaurus tuberiferous Rozhdestvensky, 1968||Turonian-Coniacian (LK) of Kazakhstan||Aralosaurus is known from much of a skull that preserves a distinctive arched nasal region. In the past, it has been tied to the "gryposaur" saurolophines, from the idea that the crest represented a gryposaur-style nasal arch, but recent research suggests that instead what we see is a small hollow lambeosaurine nasal crest, and that this is the most basal lambeosaurine.|
|Canardia garonnensis Prieto-Márquez, Dalla Vecchia, Gaete, and Galobart, 2013||late Maastrichtian (LK) of France||Canardia is a basal lambeosaurine based on a maxilla and known from a selection of bones from the skull, girdles, and arm. As usual for lambeosaurines found outside of Alberta, the crest is not known; paleontologists often remark about sauropods missing their skulls, but clearly lambeosaurines did not want to be left behind in the business of posthumus irritation.|
|Pararhabdodon isonensis Casanovas-Cladellas, Santafe-Llopis, and Isidoro Llorens, 1993 (?Koutalisaurus)||Maastrichtian (LK) of Spain and ?France||Pararhabdodon has gone through several reassessments. It was originally described as a basal iguanodontian somewhat like Rhabdodon, then as a small lambeosaurine, then as a basal hadrosaurid close to the saurolophine-lambeosaurine split, and now again a lambeosaurine, possibly in a clade with Tsintaosaurus.|
|Tsintaosaurus spinorhinus Yang, 1958||early-mid Maastrichtian (LK) of China||Tsintaosaurus seems to exist, in the
popular mind anyway, only for its crest. This feature has long been
reconstructed as a unicorn-style prong arising in front of the eyes, often
with a skin sail or inflatable air sacs to enhance it. During the 1990s
and early 2000s, it was the fashion to decry Tsintaosaurus: that it
was a chimera of lambeosaurine and saurolophine material, that the famous
crest was an "artifact" of a mistaken reconstruction and really
just a displaced bone from elsewhere in the face. More recent work
established it as a fairly basal lambeosaurine, with the "unicorn
spike" repositioned and reoriented to serve as part of a more
paddle-like vertical structure.
The name is not pronounced like how it looks, but instead along the lines of "ching-dow saurus", with a soft "g".
|Jaxartosaurus aralensis Riabinin, 1939||Turonian-?Santonian (LK) of Kazakhstan||This animal is based on a partial braincase from a young individual, showing the characteristic swelling in front where the crest grows.|
|Amurosaurus riabinini Bolotsky and Kurzanov, 1991||late Maastrichtian (LK) of Russia||This is a large Russian lambeosaurine, based on a partial skull with a large amount of referred skeletal material (although Charonosaurus and Olorotitan surely muddy the waters as far noncranial material goes). The crest is not preserved, but has been restored in "corythosaur" mode based on the rest of the skull. It may be basal to the parasaurolophinid/lamebosaurinid split.|
|Sahaliyania elunchunorum Godefroit, Hai S., Yu T., and Lauters, 2008||Maastrichtian (LK) of China||Sahaliyania marks the fourth new lambeosaurine from the Amur River region, which is suddenly becoming quite the hotspot for these things. As in several other cases, its remains come from a very productive bonebed of multiple individuals, and we don't have a complete crest.|
|Taxon or Taxa:||Time/Place:||Comments:|
|Angulomastacator daviesi Wagner and Lehman, 2009||late Campanian (LK) of Texas||Angulomastacator is based only on a partial maxilla, but it's pretty distinctive. It's curved downward (halfway between a boomerang and a banana in shape), with the tooth row curved to match. This leaves the interesting question of what it was doing that made bending the front of its face and jaws 45° down useful. Its name "bend chewer" has a double meaning, referring both to the facial geometry and to its being found from Big Bend.|
|?Arstanosaurus akkurganensis (N.D.) Suslov and Shilin, 1982||Santonian-Campanian (LK) of Kazakhstan||This animal was originally described as a hadrosaurid, but is sometimes referred to as a neoceratopsian; the teeth were initially described as double-rooted, like those of ceratopsids, but this has turned out to be in error. Referred juvenile remains from the Santonian of Mongolia also may belong here.|
|"Hadrosaurus" paucidens (N.D.) Marsh, 1889||late middle Campanian (LK) of Montana||This animal, based on a squamosal and maxilla, appears to be a lambeosaurine hadrosaurid, although at one point it was thought to be a ceratopsid.|
|Kazaklambia convincens Bell and Brink, 2013 (originally Procheneosaurus convincens Rozhdestvensky, 1968)||Turonian-Santonian (LK) of Kazakhstan||This taxon, based on a nearly
complete skeleton, spent many years under the genus Procheneosaurus,
or sometimes as a synonym of Jaxartosaurus.
Allow me to digress. "Cheneosaurs" show up in dinosaur books published between about the 1920s and 1970s as small hadrosaurs with bulges in front of and between the eyes. They represent juveniles of other lambeosaurines of the corythosaur/hypacrosaur/lambeosaur persuasion, and as such it can be difficult to establish exactly which lambeosaurine a given cheneosaur would have grown up to be. The type of Cheneosaurus tolmanensis is thought to be a Hypacrosaurus altispinus juvenile, while Procheneosaurus/Tetragonosaurus is one of those disgusting little lumps of undissolved taxonomic cocoa powder at the bottom of a cup of instant hot chocolate. People tend to tread warily around it because the type species is probably an example of Lambeosaurus lambei, and predates it by three years. In similar cases, the general solution is to get a ruling to suppress the older name, but in this case it would be problematic because the taxonomic commission ruled back in the day to suppress Tetragonosaurus in favor of Procheneosaurus, so ruling to suppress Procheneosaurus now would just be awkward. The frustrating thing about this corner of the mess (never mind the Trachodon/Didanodon/Stephanosaurus shenanigans that resulted in 20 years of wrangling before getting it "right" with Lambeosaurus lambei) is that Procheneosaurus, the name that predates Lambeosaurus and was given official recognition over Tetragonosaurus, was published with essentially no description (it gets better) in a photograph caption (keep going) without even having a type species named; P. praeceps is "borrowed" from Tetragonosaurus. Sometimes taxonomy is inexplicable.
|Koutalisaurus kohlerorum (N.D.) Prieto-Márquez, Gaete, Rivas, Galobart, and Boada, 2006 (?Pararhabdodon)||Maastrichtian (LK) of Spain||Koutalisaurus is based on a dentary that is steeply curved inward and down, giving it a spoon-shaped jaw. The specimen is otherwise indeterminate. The type had been referred to the contemporaneous Pararhabdodon, and the two are sometimes described as synonyms.|
|Nanningosaurus dashiensis Mo J., Zhao Z., Wang W., and Xu X., 2007||LK of China||The first named valid hadrosaurid from southern China, Nanningosaurus seems to be a basal lambeosaurine, featuring expanded ischial tips. It is based on a partial skeleton including skull bones, a partial scapula, both humeri and tibiae, an ischium, a femur, and a cervical.|
|Nipponosaurus sachalinensis Nagao, 1936||late Santonian-early Campanian (LK) of "Russia"||Found on Sakhalin Island, which was at the time of discovery a Japanese holding (now owned by Russia), hence the name, this animal is a juvenile lambeosaurine. It may be the same as another lambeosaurine. Recent research suggests it could be particularly close to Hypacrosaurus.|
|Taxon or Taxa:||Time/Place:||Comments:|
|Arenysaurus ardevoli Pereda-Suberbiola, Canudo, Cruzado-Caballero, Barco, López-Martínez, Oms, and Ruiz-Omeñaca, 2009||late Maastrichtian (LK) of Spain||Arenysaurus was described as a basal lambeosaurine, possibly basal to Amurosaurus, but the two are probably more derived. It is known from cranial and postcranial remains (frustratingly, we've now got several potential basal lambeosaurines with good skeletons, but we don't have much for their crests yet). It was one of the last hadrosaurids.|
|Blasisaurus canudoi Cruzado-Caballero, Pereda-Suberbiola, and Ruiz-Omeñaca, 2010||late Maastrichtian (LK) of Spain||Blasisaurus is known from skull and jaw bones from an animal closely related to Arenyasaurus.|
|Charonosaurus jiayinensis Godefroit, Zan, and Jin, 2000||late Maastrichtian (LK) of China||Charonosaurus, the first definite Late Maastrichtian lambeosaurine, and the first good-quality lambeosaurine skull from Asia, is known from a partial skull with a possibly Parasaurolophus-like tube crest and bonebed material. It was quite large, with one femur measuring 135 cm (about 53 inches) long. A few probable synonyms are floating around, including the lengthy "Heilongjiangosaurus". Even more odd is the possibility that it is synonymous with Mandschurosaurus (better known here as "Trachodon" amurensis).|
|Parasaurolophus: Parks, 1922||P. walkeri (type) Parks, 1922||late middle-early late Campanian (LK) of Alberta||Parasaurolophus is a rare but famous
lambeosaurine, instantly recognizable from the long bony tube projecting from the top-rear
of the skull in a graceful curve. This tube has a number of internal
passages, and is more complex than previously thought. The main passages start at the nostril, head back the length of the crest, turn
around in the end, head down the underside of the crest towards the head, and leave the
crest back in the skull. At times it has been restored with a skin-sail between the
crest and neck, although that seems to have fallen out of favor.
The taxonomy of Parasaurolophus are unusually convoluted for a genus with only three species; suffice it to say that there appears to have been separate northern and southern populations. The crest of P. tubicen is more complicated than that of the type, while P. cyrtocristatus' is small, suggesting a juvenile or female (if females had smaller crests than males).
On a lighter note: there are at least two distinct pronunciations circulating. The minority (including me), at least among professionals, say: pare-ah-ser-RAUH-loh-fus, while the majority say par-ah-saur-ah-LOH-fus.
|P. tubicen Wiman, 1931 (including P. cyrtocristatus Ostrom, 1961)||late middle-?middle late Campanian (LK) of New Mexico and ?Utah|
Lambeosaurini: These animals have amazingly convoluted taxonomies, due to the fact that in the earlier days of dinosaur paleontology each skull that was a little different from a type specimen was given a new species name, when it probably was just a variant due to age, gender, or preservation. In older works, you may see these animals referred to as the "hooded duckbills." You may also see reference to the "cheneosaurs," based on the genera Cheneosaurus and Procheneosaurus, which were thought to represent small crested adult hadrosaurids, but actually were the juveniles of various lambeosaurins.
|Taxon or Taxa:||Time/Place:||Comments:|
|Corythosaurus: Brown, 1914||C. casuarius (type) Brown, 1914||late middle Campanian (LK) of Alberta||One of the best-known hadrosaurids, with remains including
skin impressions for most of the body, Corythosaurus is most famous
for its helmet
or half dinner plate-like crest. It is known from remains belonging to at least
twenty individuals, and is a characteristic Judithian dinosaur.
Although sexual dimorphism has been a standard explanation for skull variation in adults, better stratigraphic data indicates two time-successive species, older C. casuarius and younger C. intermedius. C. casuarius has the classic tall crest, while C. intermedius has something not unlike Hypacrosaurus, with a shallower angle at the transition between the beak and the main part of the skull.
|C. intermedius Parks, 1923||early late Campanian (LK) of Alberta|
|Hypacrosaurus altispinus Brown, 1913||middle Maastrichtian (LK) of Alberta||A characteristic Edmontonian dinosaur, H. altispinus has a crest that resembles a shorter and more triangular Corythosaurus crest, with a short spine jutting back in the rear. It also has very tall neural spines, giving it a slight fin-back. Remains from between five and ten individuals have been found.|
|"Hypacrosaurus" stebingeri Horner and Currie, 1994||early late Campanian (LK) of Montana and Alberta||This taxon is considered by its describers to be transitional between the other lambeosaurines and Hypacrosaurus, although it may not belong to Hypacrosaurus. I'm taking it out to be on the safe side, because it tends to sort outside of a monophyletic relationship with the type species. It is known from remains including juveniles and eggs.|
|Lambeosaurus: Parks, 1923||L. lambei (type) Parks, 1923||early late Campanian (LK) of Alberta||Lambeosaurus, the
"hatchet-crested duckbill", is a bit more complicated. It
includes at least three species.
L. lambei has the classic hatchet-shaped crest, with a large lobe up front over the beak and a short solid spine going back over the rear of the skull. Chronologically, it is the middle of the three species. Like several other hadrosaurids endowed with spine-like projections, it has been suggested that a skin sail was attached to the spine.
L. clavinitialis has a more modest crest, and from the 1970s to the early 2000s was suggested to be the female of L. lambei. Finer stratigraphic information indicates that it is instead the earliest of the three species. I am not certain if it had the backspike like L. lambei; the type doesn't have one, but at least one other skull assigned to the species does.
L. magnicristatus is a much rarer species, only present at the top of the Dinosaur Park Formation. It has a large, rounded and greatly expanded crest, with a pompadour form and essentially no backspike.
|L. clavinitialis Sternberg, 1935||early Late Campanian (LK) of Alberta|
|L. magnicristatus Sternberg, 1935||early late Campanian (LK) of Alberta|
|Magnapaulia laticaudus Prieto-Márquez, Chiappe, and Joshi, 2012 (originally Lambeosaurus laticaudus Morris, 1981)||Campanian (LK) of Mexico||For much of its history before about 2010 or so, this taxon was known as an obscure, tall-spined lambeosaurine of generous proportions (Morris suggested that it could be over 50 feet long and 20 tons, based on referred material, but it was probably closer to 40 feet and not nearly so ample). The original generic assignment was tentative, which wasn't helped by the absence of the crest.|
|Olorotitan arharensis Godefroit, Bolotsky, and Alifanov, 2003||late? Maastrichtian (LK) of Russia||Based on a partial skeleton of a hadrosaur possibly 12 meters long, I originally thought this animal was going to turn out to be a saurolophine (by allusion to Anatotitan [Edmontosaurus]), but it's a lambeosaurine. It has a tall lambeosaurin-type crest, but pushed back on the skull and given a fan-like expansion; by comparison to Lambeosaurus, it has its "hatchet" on backwards.|
|Velafrons coahuilensis Gates, Sampson, Delgado de Jesús, Zanno, Eberth, Hernandez-Rivera, Aguillón Martínez, and Kirkland, 2007||late Campanian (LK) of Mexico||Velafrons is based on a mostly complete juvenile skull with one of those crests that looks like a little dome leaning over the eyes, just about to extend backward on the skull. My first question was how does it relate to ?Lambeosaurus [now Magnapualia] laticaudus; they are not the same thing, based on the form of the premaxilla. They do share one thing striking, though; ?L. laticaudus was immense, and the type individual of Velafrons was large for a lambeosaurine of its growth stage, suggesting it too was a big lambeosaurine. This is not confined to one branch of Hadrosauridae; Kritosaurus sp. from Mexico is also significantly larger than its cousins elsewhere.|
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