FIGURE 1 in Oology And The Evolution Of Thermophysiology In Saurischian Dinosaurs: Homeotherm And Endotherm Deinonychosaurians?

FIGURE 1. Cladogram inspired from Clark et al., 2002 and Buffetaut et al., 2005, and oological analyses from Grellet-Tinner et al., (2006) and Grellet-Tinner and Makovicky (in press). Note the coeveal appearance of a change in the architecture of the nest, egg shape, and eggshell structure namely in oviraptorids and at the level of troodontids. All these evolutionary transformation reflect a change of thermophysiology, interpreted as an avian-like endothermy in troodontids. Letters indicate the appearance of synapomorphies and when followed by a negative sign indicate a reversal (homoplasy). The optimization of several of these characters is putative and likely to change when more taxa are described in the future. Node 1- Sauropoda; Node 2- Maniraptora; Node 3- Paraves; Node 4- Avialae; Node 5- Ornithothoraces; Node 6- Neornithines Clade 1- Titanosauria;Clade 2- Oviraptorosauria; Clade 3- Troodontidae; Clade 4- Dromaeosauridae; Clade 5- an unidentified coelurosaurid from Phu Phok; Clade 6- possible enantiornithine from Néuquen; Clade 7- Neognathae; Clade 8- Paleognathae Characters a. Presence of surficial ornamentation; b. Acicular crystals as building blocks of the eggshell structure; c. Eggs contained within a rimed nest; d. Nodular ornamentation in titanosaurids; e. Presence of two and aprismatic layers; f. Acicular crystals limited to layer 1; g. Linear ornamentation; h. Elongated eggs; i. Presence of a small-air cell; j. Monoautochronic ovideposition as indicated by the eggs arranged in pairs; k. Eggs are laid on the perimeters of circles that superposed in 2-3 layers and with an empty space in the center of the clutch; l. Presence of brooding behavior; m. Differentiation of organic lines within layer 2; n. Presence of blade-shaped crystals in layer 1; o. Presence of a single circle of eggs; p. Presence of a fully developed air cell; q. No space devoid of eggs in the center of the clutch; r. Reduction from two to one functioning ovary; s. Presence of two and prismatic eggshell structural layers; t. Eggs are vertically oriented in the substrate with air cell up; u. Absence of eggshell surficial ornamentation; v. Presence of bi-modial nodular ornamentation; x. Presence of three prismatic eggshell structural layers; y. Layer 1 wider than layer 2.