Vertebral morphology, dentition, age, growth, and ecology of the large lamniform shark Cardabiodon ricki

Abstract

Cardabiodon ricki and Cardabiodon venator were large lamniform sharks with a patchy but global distribution in the Cenomanian

Mechanical behavior of shark vertebral centra at biologically relevant strains

“…Greater mineral content has been shown to significantly increase centrum stiffness and strength (Porter et al, 2007). The amount and arrangement of this mineralization can vary among species, ontogenetically and within an individual (Newberry et al, 2015;Porter et al, 2006Porter et al, , 2007Cailliet and Goldman, 2004;Dingerkus et al, 1991;Urist, 1962;Ridewood, 1921). For example, Carcharhiniformes have double cones made of densely calcified wedges that stretch between opposing arms of the corpus calcarea to form the intermedialia, while Lamniformes have radiating lamellae with a less calcified intermedialia ( Fig.…”

“…For example, Carcharhiniformes have double cones made of densely calcified wedges that stretch between opposing arms of the corpus calcarea to form the intermedialia, while Lamniformes have radiating lamellae with a less calcified intermedialia ( Fig. 1; Natanson et al, 2018;Newberry et al, 2015;Ridewood, 1921). These data are congruent with the study of Porter et al (2006), which found that the sandbar shark (Carcharhinus plumbeus), silky shark (Carcharhinus falciformis) and smooth hammerhead (Sphyrna zygaena), all Carcharhiniformes species, had almost 10% greater mineral content than the shortfin mako (Isurus oxyrinchus), a Lamniformes shark.…”

Articulated remains of the extinct shark Ptychodus (Elasmobranchii, Ptychodontidae) from the Upper Cretaceous of Spain provide insights into gigantism, growth rate and life history of ptychodontid sharks

“…The combination of the above mentioned characters (parallel lamellae, concentric lamellae, asterospondyl centra), the size of the vertebral centra and the stratigraphic age (Cretaceous) of these species, leads us to the assumption that both specimens, EMRG-Chond-SK-1 and Rozefelds' QMF18264, are ptychodontid sharks. Other big sharks from the Late Cretaceous are known from the order Lamniformes (e.g., †Cretalamna, †Cretodus, †Cretoxyrhina), but can easily be ruled out because they are known to have a different mineralization pattern of the vertebral centra (i.e., the vertebral centrum is strengthened by multi-branched, densely packed lamellae), have radial lamellae on the dorsoventral axis in lateral view (which our specimen does not have), and lack parallel lamellae [12,13,48,[52][53][54][55]. The placoid scales from the sediment samples associated with the Spanish specimen represent three different morphotypes (see S1 Fig).…”

“…that this relationship can vary between species [9,10,12]. To overcome this issue, we conducted two independent approaches to estimate the total length of the examined specimen:…”

“…However, the fossil record of chondrichthyans predominantly consists of isolated teeth, which only offer limited information about the biological traits of a species. Vertebrae on the other hand yield important data on the biology and ecology of fossil elasmobranchs, but only have been described for a very limited number of extinct species [9][10][11][12][13][14].…”