Lambeosaurinae

   The lambeosaurines are the hollow-crested hadrosaurids.  On the whole, they are more robust in build when compared to the hadrosaurines, and tend to have more elongated neural spines than the hadrosaurines, giving them more of a fin-back.  In North America, they are most common in the Judithian 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, and Olorotitan.
    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 Corythosaurini (which by priority should be Lambeosaurini).  Parasaurolophini is as yet not as well-defined or well-supported as Corythosaurini, 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. 

<--Lambeosaurinae
      |--?Aralosaurus
      `--+--Tsintaosaurus
           `--+--Jaxartosaurus
                `--+--Amurosaurus
                     `--+--Parasaurolophini  
                          |    |--Charonosaurus
                          |    `--Parasaurolophus
                          `--Corythosaurini
                               |--Nipponosaurus
                               `--+--Lambeosaurus
                                    `--+--Olorotitan
                                         |--Corythosaurus
                                         `--Hypacrosaurus

Lambeosaurinae:

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" hadrosaurines, 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.
Tsintaosaurus spinorhinus Yang, 1958 early-mid Maastrichtian (LK) of China This animal is famous for the unicorn-like spine projecting from its skull.  This has been called into question in the past, and accused of being created by skull-bone displacement after death, but other remains appear to show it existed.  A skin sail may have been attached to it.  Tsintaosaurus is based on chimerical remains, belonging to both lambeosaurines and hadrosaurines.  Today it is usually limited to the lambeosaurine remains.  The hadrosaurine remains appear to come from an animal like Tanius.  It is not pronounced like how it looks like it may sound, but instead along the lines of "ching-dow saurus."  Although here a more basal lambeosaurine, it could also be aligned with Parasaurolophus.
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"/"lambeosaurinid" split.

Lambeosaurinae i.s.:

Taxon or Taxa: Time\Place: Comments:
?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 neoceratopian; the teeth were initially described as double-rooted, like those of ceratopids, 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 ceratopid.
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. 
"Procheneosaurus" convincens (N.D.) Rozhdestvensky, 1968 Turonian-Santonian (LK) of Kazakhstan This indeterminate taxon, based on a nearly complete skeleton, may be an early lambeosaurine, or the same as Jaxartosaurus.
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.

Parasaurolophini: 

Taxon or Taxa: Time\Place: Comments:
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 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-?late Campanian (LK) of New Mexico and ?Utah

Corythosaurini:  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 variation 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 corythosaurins.

Taxon or Taxa: Time\Place: Comments:
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.
Lambeosaurus: Parks, 1923 L. lambei (type) Parks, 1923 late middle Campanian (LK) of Alberta L. lambei is recognized from its crest, which is hatchet shape up front over the beak and has a short solid spine going back over the rear of the skull.  A contemporary of Corythosaurus, it is also known from remains belonging to over twenty individuals.  Like several other hadrosaurids endowed with spine-like projections, it has been suggested that a skin sail was attached to the spine.
L. magnicristatus Sternberg, 1935 late middle Campanian (LK) of Alberta A much rarer species, L. magnicristatus has a large, rounded and greatly expanded hatchet crest, with much less of a spine at the rear.
?L. laticaudus Morris, 1981 Campanian (LK) of Mexico Known from remains suggesting a fifty-foot long lambeosaurine, ?L. laticaudus is known for its very tall neural spines.  It may be closer to Hypacrosaurus.
Corythosaurus casuarius 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.  Perhaps not surprisingly, certain individuals (not the biggest, presumably adults, but still good-sized) have crests which provide Hypacrosaurus foreshadowing with the shallower angle at the transition between the beak and the main part of the skull, and a small pointed process at the caudal end (this actually can be seen in some of the largest individuals, but it's not near as prominent as in Hypacrosaurus).  Although sexual dimorphism has been a standard explanation for skull variation in adults, better stratigraphic data suggests time-successive species (as yet not formally defined).
Probably synonymous with this genus is the collection of postcranial remains named Pteropelyx grallipes by Cope in 1889.  It should have priority, but since no one has talked about Pteropelyx since Lull and Wright in 1942, or has taken it seriously as a useful name since Lambe in 1902 (who thought it to be a subgenus of Trachodon), it has been ignored, and should probably be suppressed.
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 a hadrosaurine (by allusion to Anatotitan [probably a species of Edmontosaurus]), but it's a lambeosaurine.  It has a tall corythosaurin-type crest, but pushed back on the skull and given a fan-like expansion; by comparison to Lambeosaurus, it has its "hatchet" on backwards.
Hypacrosaurus: Brown, 1913 H. altispinus (type) Brown, 1913 early 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.
H. stebingeri Horner and Currie, 1994 latest middle Campanian (LK) of Montana and Alberta This taxon is considered by its describers to be transitional between the other lambeosaurines and Hypacrosaurus.  It is known from remains including juveniles and eggs.

Corythosaurini: i.s.:

Taxon or Taxa: Time/Place: Comments:
Barsboldia sicinskii Maryanska and Osmolska, 1981 (?Hypacrosaurus) early Maastrichtian (LK) of Mongolia This animal is based upon most of the rear half of one individual.  It has very tall neural spines with unique club-like expansions at the ends, possibly pathological in origin.  I suspect that it may be the same as Hypacrosaurus, but I have no concrete evidence to support this.
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 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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