Abstract The Asteridae is a group of some 80,000 species of flowering plants characterized by their fused corollas and iridoid compounds. Recent phylogenetic analyses have helped delimit the group and have identified four main clades within it; Cornales, Ericales, Lamiids and Campanulids, with the last two collectively known as the Euasteridae. A search for the oldest fossils representing asterids yielded a total of 261 records. Each of these fossils was evaluated as to the reliability of its identification. The oldest accepted fossils for each clade were used to estimate minimum ages for the whole of the Asteridae. The results suggest that the Asteridae dates back to at least the Turonian, Late Cretaceous (89.3 mya) and that by the Late Santonian-Early Campanian (83.5 mya) its four main clades were already represented in the fossil record.

Resumen Las Asteridas son un grupo de unas 80,000 especies de plantas con flor caracterizadas por sus corolas fusionadas y compuestos iridoides. Analisis filogeneticos recientes han ayudado a delimitar al grupo y han identificado cuatro clados principales en el; Cornales, Ericales, Lamiidas y Campanulidas, con las ultimas dos conocidas colectivamente como Euasteridas. Una busqueda por los fosiles mas antiguos que representan asteridas produjo un total de 261 registros. Cada uno de estos fosiles fue evaluado en cuanto a la confiabilidad de su identificacion. Los fosiles aceptados mas antiguos de cada clado se usaron para estimar edades minimas para las Asteridas. Los resultados sugieren que las Asteridas datan al menos del Turoniano, Cretacico Tardio (89.3 ma) y que para el Santoniano Tardio-Campaniano Temprano (83.5 ma) sus cuatro clados principales ya estaban representados en el registro fosil.

Keywords Asteridae * Campanulids * Euasteridae * Fossil. Lamiids * Minimum Age

Introduction

The Asteridae

The Asteridae is a group of flowering plants characterized by their fused corollas and iridoid compounds (Bremer et al., 2002). This group has been recognized by botanists since the eighteenth century, receiving names such as the Monopetalae, Gamopetalae or Sympetalae (Wagenitz, 1992) all of which allude to the characteristic connate corolla. In more recent times, classification systems based on morphology such as those of Cronquist (1981) and Yakhtajan (1997), recognized relationships among several families displaying these characters and placed them in the similar subclass(es): Asteridae in the case of Cronquist (1981) and Asteridae, Lamiidae and Cornidae of Takhtajan (1997). With the advent of molecular systematics, the delimitation of the group has become clearer (Chase et al., 1993; Savolainen et al., 2000; Soltis et al., 2000; APG, 1998, 2003, 2009). Most of the taxa that Cronquist (1981) and Takhtajan (1997) placed in their Asteridae or separately in the Asteridae, Lamiidae and Cornidae are still accommodated in the current concept of Asteridae, but several other taxa traditionally placed in the Dillenidae and Rosidae have also been proven to be asterids (compare the three classification systems in "Appendix A"). This new, expanded and redefined Asteridae includes some 80,000 species in 102-106 families, that is, about 1/3-1/4 of all angiosperm species (APG, 1998, 2003, 2009; Bremer et al., 2002).

The...