Paleopsilopterus Alvarenga, 1985

Alvarenga, Herculano M. F. & Höfling, Elizabeth, 2003, Systematic Revision Of The Phorusrhacidae (Aves: Ralliformes), Papéis Avulsos de Zoologia 43 (4), pp. 55-91 : 84-86

Genus Paleopsilopterus Alvarenga, 1985

Type Species – Paleopsilopterus itaboraiensis Alvarenga, 1985 .

Included Species – Only the type species.

Distribution – Middle Paleocene of Brazil (Rio de Janeiro).

Diagnosis – Heavier built than Psilopterus , similar to Procariama . The intercotylar tubercle of the tarsometatarsus is wide and rounded, and lower than in the

Horizon and Locality – Middle Paleocene (Itaboraian) of southeastern Brazil: Rio de Janeiro, Itaboraí.

Measurements – Table 8 and Alvarenga (1985 a).

Illustrations – Alvarenga (1985 a).

Remarks – It is the oldest Phorusrhacidae known.

Subfamily Mesembriornithinae

Kraglievich, 1932 stat. n.

Mesembriorniidae Kraglievich, 1932 . Hermosiornidae Rovereto, 1914 ; Brodkorb, 1967 (syn.

of Prophorhacinae).

Hermosiorniidae Kraglievich, 1932 Hermosiornithidae Wetmore, 1934 . Hermosiornithinae Patterson & Kraglievich, 1960. Prophororhacinae, Brodkorb, 1967; Mourer-Chauviré,

1981.

Diagnos i s Revised – This is a relatively middle-sized Phorusrhacidae . The upper maxilla is relatively low, especially in the middle part, being rostrally lengthened ( Fig. 1H and Fig. 26D ). There is a short and relatively low mandibular symphysis. The coracoid is anchylosed to the clavicle ( Figs. 4G and 4H ). On the tibiotarsus, the apex of the internal condyle is more prominent and proximally bent, thus forming a more acute angle (when seen in internal view), with the diaphysis. They are the slimmest of the Phorusrhacidae , in which the tarsometatarsus reaches around 80 to 85% of the length of the tibiotarsus ( Fig. 33 ), and wherein the middle trochlea is distally spread, with a width equal or more than the smallest transverse diameter of the diaphysis. The Mesembriornithinae are amongst the most recent of the Phorusrhacidae ( Fig. 34 ).

Included Genera – Mesembriornis Moreno, 1889 (unique). Paleociconia australis Moreno, 1889:30 ; Moreno &

Mercerat, 1891. Driornis pampeanus Moreno & Mercerat, 1891 (part: only

femur). Hermosiornis milneedwardsi Rovereto, 1914 . Hermosiornis rapax Kraglievich, 1946 ; syn. n. Prophororhacos australis Brodkorb, 1967:172 .

Type – The centrum of a cervical vertebra associated to the proximal part of both the right tibiotarsus and fibula (MLP-140-142).

Figures

FIGURE 1. Reproduction (by E. Brettas) of some Phorusrhacidae keeping the due proportion as to size. The silhouette of a man 1.75 m high is used as a scale. A - Brontornis burmeisteri; B - Paraphysornis brasiliensis; C - Phorusrhacos longissimus; D - Andalgalornis steuletti; E - Psilopterus bachmanni; F - Psilopterus lemoinei; G - Procariama simplex; H - Mesembriornis milneedwardsi.

FIGURE 4. The coracoids of some Phorusrhacidae in comparison with Ameghinornis minor and Cariama cristata. The left coracoid of Paraphysornis brasiliensis (DGM-1418-R) viewed ventrally (A) and in lateral view (B); the right coracoid of Patagornis marshi (BMNH-A-524) in ventral view (C) and in lateral view (D); the left coracoid in ventral view of Psilopterus lemoinei (E) (PUM-15402, redrawn from Sinclair & Farr, 1932), and P. bachmanni (F) (PUM-15904, also redrawn from Sinclair & Farr, 1932); the omal extremity of the right coracoid of Mesembriornis milneedwardsi, fused with a part of the clavicle, viewed dorsally (G) (redrawn from Rovereto, 1914); a reproduction of the fused clavicle and coracoid in Mesembriornis milneedwardsi (H) (redrawn from Kraglievich, 1932); the left coracoid, viewed dorsally, of Ameghinornis minor (cast, MGHN-PQ1200) (I) and Cariama cristata (MHNT-1136) (J); sc = scapular cotyle.

FIGURE 26. Skulls of the Patagornithinae (A-C), Mesembriornithinae (D) and Psiloterinae (E-J). A - Andrewsornis abbotti (FM-P13417; from Patterson, 1941), B - Patagornis marshi (BMNH-A-516; from Andrews, 1899), C - Andalgalornis steulleti (FM-P14357); D - Mesembriornis milneedwardsi (MMP-S155); E - Procariama simplex (FM-P14525); F - Psilopterus lemoinei (FM-P13257); G - Psilopterus lemoinei (PUM-15402); H - Psilopterus lemoinei (AMNH-9157); I - Psilopterus lemoinei (PUM-15109); J - Psilopterus bachmanni (PUM-15904). G-J inverted figures from Sinclair & Farr (1910).

FIGURE 33. Bones of the hind limbs, of the Mesembriornithinae (A-G) and Psilopterinae (H-N). Mesembriornis milneedwardsi (MACN-5944; from Rovereto, 1914): A - right femur, dorsal view, B - left tibiotarsus, ventral view, and C - left tarsometatarsus, dorsal view. Mesembriornis milneedwardsi (MMP-S155): D - left femur, dorsal view, E - right tibiotarsus, ventral view. Mesembriornis incertus (FM-P14422): F - right tibiotarsus, ventral view, and G - right tarsometatarsus, dorsal view. Procariama simplex (FM-P14525): H - right femur, dorsal view, I - tibiotarsus, ventral view, and J - right tarsometatarsus, dorsal view. Psilopterus lemoinei (AMNH-9157 and 9257 from Sinclair & Farr, 1910): L - right femur, dorsal view, M - right tarsometatarsus, ventral view, and N - right tarsometatarsus, dorsal view.

FIGURE 34. Geologic time-table with the distribution of the 17 species (13 genera) of the Phorusrhacidae under consideration herein, within the diverse periods of the Cenozoic. Column on the left represents the South American mammal age, based on Tonni (1980), Mac Fadden (1985) and Marshal et al. (1986).