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. 2012;7(6):e38207.
doi: 10.1371/journal.pone.0038207. Epub 2012 Jun 12.

The lambeosaurine dinosaur Magnapaulia laticaudus from the late cretaceous of Baja California, Northwestern Mexico

Albert Prieto-Márquez  1 , Luis M Chiappe, Shantanu H Joshi
Affiliations

The lambeosaurine dinosaur Magnapaulia laticaudus from the late cretaceous of Baja California, Northwestern Mexico

Albert Prieto-Márquez et al. PLoS One. 2012.

Abstract

The taxonomy, osteology, phylogenetic position, and historical biogeography of the lambeosaurine hadrosaurid Magnapaulia laticaudus (new combination) are revised. The diagnosis of this species is amended on the basis on two autapomorphies (i.e., longest haemal arches of proximal caudal vertebrae being at least four times longer than the height of their respective centra; base of prezygapophyses in caudal vertebrae merging to form a bowl-shaped surface) and a unique combination of characters (i.e., downturned cranioventral process of the maxilla; tear-shaped external naris with length/width ratio between 1.85 and 2.85; neural spines of dorsal, sacral, and proximal caudal vertebrae being at least four times the height of their respective centra). A maximum parsimony analysis supports a sister taxon relationship between M. laticaudus and Velafrons coahuilensis. Both taxa constitute a clade of southern North American lambeosaurines, which forms a sister relationship with the diverse clade of helmet-crested lambeosaurines from northern North America that includes well-known genera like Corythosaurus, Lambeosaurus, and Hypacrosaurus. According to the results of a Dispersal-Vicariance analysis, southern North American lambeosaurines split from the northern forms via vicariance from a common ancestor that lived in both the northern and southern regions of the continent.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Geographical setting of Magnapaulia laticaudus.
Map of Baja California Norte showing the location of El Rosario; the remains of M. laticaudus were found no more than three miles west of El Rosario.
Figure 2
Figure 2. Summary of skeletal fossil representation and size range of Magnapaulia laticaudus.
Idealized lambeosaurine skeleton showing the elements preserved in T. laticaudus (cranial crest, forelimbs, and pedes of the model are based on Corythosaurus casuarius skeletons AMNH 5240 and 5338) (A). Size range of known M. laticaudus specimens (B).
Figure 3
Figure 3. Magnapaulia laticaudus, LACM 17715 (holotype), left premaxilla.
Premaxilla in rostral and slightly lateral (A), dorsolateral view (B), and ventral (C) views.
Figure 4
Figure 4. Square-Root Elastic morphometric analysis , of a set of boundaries corresponding to the external naris of various species of lambeosaurine dinosaurs.
Left premaxilla of Magnapaulia laticaudus (LACM 17715) in lateral view (A). Left lateral view of a skull of Lambeosaurus clavinitialis (CMN 8703), showing the location of the external naris (B). Bivariate plot of the two first axes of the Non-metric Multidimensional Scaling analysis performed on the results of the morphometric analysis (C). The shapes included in the analysis correspond to the following specimens: 1. Corythosaurus intermedius (CMN 8676). 2. C. casuarius (ROM 1933). 3. C. casuarius (TMP 84.121.1). 4. C. casuarius (ROM 868). 5. C. casuarius (AMNH 5338). 6. C. intermedius (ROM 845). 7. C. intermedius (CMN 8503). 8. C. intermedius (CMN 8704). 9. C. intermedius (ROM 776). 10. C. intermedius (ROM 777). 11. C. intermedius (UALVP 13). 12. Magnapaulia laticaudus (LACM 17715). 13. L. magnicristatus (CMN 8705). 14. L. magnicristatus (TMP 66.4.1). 15. Parasaurolophus walkeri (ROM 768). 16. Olorotitan arharensis (AEHM 2/845). 17. L. lambei (CMN 351). 18. L. lambei (CMN 2869). 19. L. clavinitialis (CMN 8703). 20. L. lambei (FMNH FR380). 21. L. lambei (ROM 794). 22. L. clavinitialis (TMP 81.37.1). 23. L. clavinitialis (YPM 3222). 24. Lambeosaurus sp. (CMN 8633). 25. L. lambei (ROM 1218). 26. Hypacrosaurus altispinus (CMN 8501). 27. H. altispinus (AMNH 5278). 28. H. altispinus (CMN 8675). 29. H. altispinus (ROM 702). 30. H. stebingeri (MOR 549).
Figure 5
Figure 5. Magnapaulia laticaudus, LACM 17715 (holotype), left maxilla.
Maxilla in lateral (A), dorsal (B), medial (C), and ventral (D) views.
Figure 6
Figure 6. Magnapaulia laticaudus, LACM 17715 (holotype), left jugal.
Jugal in lateral (A) and medial (B) views.
Figure 7
Figure 7. Magnapaulia laticaudus, LACM 20874, left dentary.
Dentary in lateral (A), dorsal (B), and medial (C) views.
Figure 8
Figure 8. Magnapaulia laticaudus, dentition.
LACM 17715 (holotype), rostral maxillary tooth crown in labial (A) and mesial (B) views. LACM 17715, caudal maxillary teeth in labial view view (C). LACM 17713, dentary teeth in lingual view (D). LACM 17713, occlusal plane of the dentary dental battery (E).
Figure 9
Figure 9. Magnapaulia laticaudus, selected pre-sacral vertebrae.
A. Cervical vertebra of LACM 17715 (holotype) in cranial view. B. Right lateral view of same. C. Dorsal view of same. D. Cranial dorsal vertebra of LACM 17707 in cranial view. E. Articulated series of cranial dorsal vertebrae, LACM 17707, in left lateral view. F. Cranial dorsal vertebra of LACM 17707 in caudal view. G. Caudal dorsal vertebra of LACM 20874 in cranial view. H. Left lateral view of same.
Figure 10
Figure 10. Magnapaulia laticaudus, LACM 17715 (holotype), partial sacrum.
Sacrum in right lateral (A), ventral (B), and cranial (C) views.
Figure 11
Figure 11. Magnapaulia laticaudus, caudal vertebrae.
LACM 17705, proximal caudal vertebrae in right lateral view (A). LACM 17702, proximal caudal vertebra in right lateral (B) and cranial (C) views. LACM 20873, proximal to middle articulated caudal vertebrae in right lateral view (D).
Figure 12
Figure 12. Magnapaulia laticaudus, LACM 17702, detail of the prezygapophyses and the base of the neural spine of a proximal caudal vertebra.
Vertebra in dorsal (A), cranial (B), and ventral (C) views.
Figure 13
Figure 13. Magnapaulia laticaudus, LACM 17715 (holotype), axial elements and pectoral girdle.
Left sternum in ventral view (A). Left coracoid in cranial (B), lateral (C), and caudal (D) views. Right scapula in lateral view (E).
Figure 14
Figure 14. Magnapaulia laticaudus, humeri.
LACM 17715 (holotype), right humerus in craniomedial (A), caudal (B), caudolateral (C), and cranial (D) views. LACM 17712, partial right humerus in craniomedial (E) and caudal (F) views. LACM 17716, right humerus in craniomedial (G) and caudal (H) views.
Figure 15
Figure 15. Magnapaulia laticaudus, LACM 20874, right ilium.
Ilium in lateral (A) and ventral (B) views.
Figure 16
Figure 16. Magnapaulia laticaudus, LACM 20874, pubes.
Right pubis in dorsal (A), caudolateral (B), lateral (C), and ventral and slightly lateral (D) views. Left pubis in lateral (F) and caudal (H) views.
Figure 17
Figure 17. Lambeosaurine ischia from Baja California, Mexico.
Magnapaulia laticaudus left ischium, LACM 17715 (holotype), in lateral view (A). Left ischium of an indeterminate lambeosaurine dinosaur from La Bocana Roja Formation, LACM 28990, in lateral view (B).
Figure 18
Figure 18. Magnapaulia laticaudus, LACM 20874, proximal ischia.
Right ischium in dorsal (A), craniodorsal (B), lateral (C), and cranial (D) views. Left ischium in medial (E), craniolateral (G), and lateral (H) views. Pubic process of left ischium showing craniodorsally-facing triangular facet (F).
Figure 19
Figure 19. Magnapaulia laticaudus, hindlimb elements.
LACM 17715 (holotype), right femur in cranial (A), medial (B), caudal (C), and lateral (D) views. LACM 20876, left tibia in cranial (E), lateral (F), caudal (G), and medial (H) views.
Figure 20
Figure 20. Magnapaulia laticaudus, hindlimb elements.
LACM 20874, proximal half of the left fibula in proximal (A), lateral (B), and cranial (C) views. LACM 17715 (holotype), right metatarsal III in dorsal (D) and medial (E) views.
Figure 21
Figure 21. Magnapaulia laticaudus, LACM 17712, integumentary structures.
Natural cast of scales (A). Scale impressions (B). Casts and impressions of smaller scales (C). Impressions of the co-occurrence of small and large scales in a single skin patch (D). Natural cast of scales adjacent to the cast of a possible osteoderm (arrow) (E).
Figure 22
Figure 22. Single most parsimonious tree resulting from maximum parsimony analysis, showing the phylogenetic position of Magnapaulia laticaudus within Lambeosaurinae.
The numbers above the branches represent bootstrap frequencies, whereas those below are decay indices (Bremer support).
Figure 23
Figure 23. Time-calibrated phylogram of Lambeosaurinae based on the phylogenetic hypothesis shown in Fig. 22.
The letters at each node indicate ancestral areas as inferred in the Dispersal-Vicariance analysis; a combination of two letters represents a widespread range of the ancestor in both of the areas indicated by each letter. The numbers to the left of the taxon names are the estimated ages in millions of years. When absolute age estimates are not available but only time ranges (e.g., middle-late Maastrichtian), the age of the taxon is approximated as the mid-point of a particular geochronological stage (numbers between brackets). The literature sources for each of the taxon's ages are as follows: Amurosaurus riabinini ; Aralosaurus tuberiferus , ; Charonosaurus jiayinensis ; Corythosaurus spp., Lambeosaurus spp., and Parasaurolophus walkeri ; Hypacrosaurus altispinus ; H. stebingeri ; Magnapaulia laticaudus ; Jaxartosaurus aralensis ; Olorotitan arharensis ; Pararhabdodon isonensis ; Parasaurolophus tubicen and P. cyrtocristatus ; Sahaliyania elunchunorum ; Tsintaosaurus spinorhinus ; and Velafrons coahuilensis . Geochronological ages are from Gradstein et al. .
Figure 24
Figure 24. Scatterplot showing the relationship between the distal half of the humerus and the total length of the bone for a sample of lambeosaurine hadrosaurids.
Figure 25
Figure 25. Scatterplot showing the relationship between the length of the humerus and total body length for a sample of hadrosaurid dinosaurs.
Lengths measured by the authors, unless otherwise indicated. The numbers indicate the following specimens: 1, Prosaurolophus maximus ROM 787; 2, Hypacrosaurus altispinus CMN 8501; 3, Edmontosaurus annectens SM R4036; 4, Olorotitan ararhensis AEHM 2/845 (body length from [37]); 5, E. annectens YPM 2182; 6, Parasaurolophus cyrtocristatus FMNH P27393; 7, Corythosaurus casuarius AMNH 5338; 8, Gryposaurus notabilis ROM 764; 9, Brachylophosaurus canadensis MOR 794; 10, Saurolophus osborni AMNH 5220; 11, E. regalis CMN 8399; 12, E. regalis ROM 801; G. notabilis MSNM V345 (data after [87]). The measurements from Shantungosaurus giganteus are from .
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